diff --git a/package.json b/package.json
index 90511293b6a..15e51ecb428 100644
--- a/package.json
+++ b/package.json
@@ -108,9 +108,40 @@
     "version-check": "node ./scripts/tasks/version-check.js"
   },
   "jest": {
-    "projects": [
-      "<rootDir>/scripts/jest/stack.config.json",
-      "<rootDir>/scripts/jest/fiber.config.json"
-    ]
+    "modulePathIgnorePatterns": [
+      "/.module-cache/",
+      "<rootDir>/build/",
+      "<rootDir>/scripts/rollup/shims/",
+      "<rootDir>/scripts/bench/"
+    ],
+    "transform": {
+      ".*": "./scripts/jest/preprocessor.js"
+    },
+    "setupFiles": [
+      "./scripts/jest/setup.js",
+      "./scripts/jest/environment.js"
+    ],
+    "setupTestFrameworkScriptFile": "./scripts/jest/test-framework-setup.js",
+    "testRegex": "/__tests__/.*(\\.js|coffee|ts)$",
+    "moduleFileExtensions": [
+      "js",
+      "json",
+      "node",
+      "coffee",
+      "ts"
+    ],
+    "roots": [
+      "<rootDir>/eslint-rules",
+      "<rootDir>/mocks",
+      "<rootDir>/scripts",
+      "<rootDir>/src",
+      "node_modules/fbjs"
+    ],
+    "collectCoverageFrom": [
+      "src/**/*.js",
+      "!src/__mocks__/vendor/third_party/*.js",
+      "!src/test/*.js"
+    ],
+    "timers": "fake"
   }
 }
diff --git a/scripts/babel/transform-object-assign-require.js b/scripts/babel/transform-object-assign-require.js
index d11fba24663..3f3430d3e47 100644
--- a/scripts/babel/transform-object-assign-require.js
+++ b/scripts/babel/transform-object-assign-require.js
@@ -13,16 +13,12 @@ module.exports = function autoImporter(babel) {
   const t = babel.types;
 
   function getAssignIdent(path, file, state) {
-    if (!state.id) {
-      state.id = path.scope.generateUidIdentifier('assign');
-      path.scope.getProgramParent().push({
-        id: state.id,
-        init: t.callExpression(t.identifier('require'), [
-          t.stringLiteral('object-assign'),
-        ]),
-      });
+    if (state.id) {
+      return state.id;
     }
-    return state.id;
+    const id = file.addImport('object-assign', 'default', 'assign');
+    state.id = id;
+    return id;
   }
 
   return {
diff --git a/scripts/error-codes/replace-invariant-error-codes.js b/scripts/error-codes/replace-invariant-error-codes.js
index 820953377b3..d252a03f1cc 100644
--- a/scripts/error-codes/replace-invariant-error-codes.js
+++ b/scripts/error-codes/replace-invariant-error-codes.js
@@ -20,19 +20,17 @@ module.exports = function(babel) {
   var SEEN_SYMBOL = Symbol('replace-invariant-error-codes.seen');
 
   // Generate a hygienic identifier
-  function getProdInvariantIdentifier(path, localState) {
-    if (!localState.prodInvariantIdentifier) {
-      localState.prodInvariantIdentifier = path.scope.generateUidIdentifier(
-        'prodInvariant'
-      );
-      path.scope.getProgramParent().push({
-        id: localState.prodInvariantIdentifier,
-        init: t.callExpression(t.identifier('require'), [
-          t.stringLiteral('reactProdInvariant'),
-        ]),
-      });
+  function getProdInvariantIdentifier(path, file, localState) {
+    if (localState.prodInvariantIdentifier) {
+      return localState.prodInvariantIdentifier;
     }
-    return localState.prodInvariantIdentifier;
+    const id = file.addImport(
+      'reactProdInvariant',
+      'default',
+      'reactProdInvariant'
+    );
+    localState.prodInvariantIdentifier = id;
+    return id;
   }
 
   var DEV_EXPRESSION = t.identifier('__DEV__');
@@ -44,7 +42,7 @@ module.exports = function(babel) {
 
     visitor: {
       CallExpression: {
-        exit: function(path) {
+        exit: function(path, file) {
           var node = path.node;
           // Ignore if it's already been processed
           if (node[SEEN_SYMBOL]) {
@@ -59,7 +57,7 @@ module.exports = function(babel) {
             path.get('arguments')[0].isStringLiteral({value: 'invariant'})
           ) {
             node[SEEN_SYMBOL] = true;
-            getProdInvariantIdentifier(path, this);
+            getProdInvariantIdentifier(path, file, this);
           } else if (path.get('callee').isIdentifier({name: 'invariant'})) {
             // Turns this code:
             //
@@ -110,7 +108,7 @@ module.exports = function(babel) {
 
             devInvariant[SEEN_SYMBOL] = true;
 
-            var localInvariantId = getProdInvariantIdentifier(path, this);
+            var localInvariantId = getProdInvariantIdentifier(path, file, this);
             var prodInvariant = t.callExpression(
               localInvariantId,
               [t.stringLiteral(prodErrorId)].concat(node.arguments.slice(2))
diff --git a/scripts/jest/fiber.config.json b/scripts/jest/fiber.config.json
deleted file mode 100644
index c6f47bf86cd..00000000000
--- a/scripts/jest/fiber.config.json
+++ /dev/null
@@ -1,38 +0,0 @@
-{
-  "modulePathIgnorePatterns": [
-    "/.module-cache/",
-    "<rootDir>/build/",
-    "<rootDir>/scripts/rollup/shims/",
-    "<rootDir>/scripts/bench/"
-  ],
-  "rootDir": "../../",
-  "transform": {
-    ".*": "./scripts/jest/preprocessor.js"
-  },
-  "setupFiles": [
-    "./scripts/jest/fiber.setup.js",
-    "./scripts/jest/environment.js"
-  ],
-  "setupTestFrameworkScriptFile": "./scripts/jest/test-framework-setup.js",
-  "testRegex": "/__tests__/.*(\\.js|coffee|ts)$",
-  "moduleFileExtensions": [
-    "js",
-    "json",
-    "node",
-    "coffee",
-    "ts"
-  ],
-  "roots": [
-    "<rootDir>/eslint-rules",
-    "<rootDir>/mocks",
-    "<rootDir>/scripts",
-    "<rootDir>/src",
-    "node_modules/fbjs"
-  ],
-  "collectCoverageFrom": [
-    "src/**/*.js",
-    "!src/__mocks__/vendor/third_party/*.js",
-    "!src/test/*.js"
-  ],
-  "timers": "fake"
-}
diff --git a/scripts/jest/preprocessor.js b/scripts/jest/preprocessor.js
index 7727b1b2d8b..24b563d652b 100644
--- a/scripts/jest/preprocessor.js
+++ b/scripts/jest/preprocessor.js
@@ -48,6 +48,8 @@ var babelOptions = {
         }),
       },
     ],
+    // TODO: is this enough?
+    require.resolve('babel-plugin-transform-es2015-modules-commonjs'),
     // Keep stacks detailed in tests.
     // Don't put this in .babelrc so that we don't embed filenames
     // into ReactART builds that include JSX.
diff --git a/scripts/jest/fiber.setup.js b/scripts/jest/setup.js
similarity index 74%
rename from scripts/jest/fiber.setup.js
rename to scripts/jest/setup.js
index 9972f16fff8..a0fbd78530a 100644
--- a/scripts/jest/fiber.setup.js
+++ b/scripts/jest/setup.js
@@ -2,12 +2,6 @@
 
 // We want to globally mock this but jest doesn't let us do that by default
 // for a file that already exists. So we have to explicitly mock it.
-jest.mock('ReactDOMFeatureFlags', () => {
-  const flags = require.requireActual('ReactDOMFeatureFlags');
-  return Object.assign({}, flags, {
-    useFiber: true,
-  });
-});
 jest.mock('ReactFeatureFlags', () => {
   const flags = require.requireActual('ReactFeatureFlags');
   return Object.assign({}, flags, {
diff --git a/scripts/jest/stack.config.json b/scripts/jest/stack.config.json
deleted file mode 100644
index 77972ca00cb..00000000000
--- a/scripts/jest/stack.config.json
+++ /dev/null
@@ -1,38 +0,0 @@
-{
-  "modulePathIgnorePatterns": [
-    "/.module-cache/",
-    "<rootDir>/build/",
-    "<rootDir>/scripts/rollup/shims/",
-    "<rootDir>/scripts/bench/"
-  ],
-  "rootDir": "../../",
-  "transform": {
-    ".*": "./scripts/jest/preprocessor.js"
-  },
-  "setupFiles": [
-    "./scripts/jest/stack.setup.js",
-    "./scripts/jest/environment.js"
-  ],
-  "setupTestFrameworkScriptFile": "./scripts/jest/test-framework-setup.js",
-  "testRegex": "/__tests__/.*(\\.js|coffee|ts)$",
-  "moduleFileExtensions": [
-    "js",
-    "json",
-    "node",
-    "coffee",
-    "ts"
-  ],
-  "roots": [
-    "<rootDir>/eslint-rules",
-    "<rootDir>/mocks",
-    "<rootDir>/scripts",
-    "<rootDir>/src",
-    "node_modules/fbjs"
-  ],
-  "collectCoverageFrom": [
-    "src/**/*.js",
-    "!src/__mocks__/vendor/third_party/*.js",
-    "!src/test/*.js"
-  ],
-  "timers": "fake"
-}
diff --git a/scripts/jest/stack.setup.js b/scripts/jest/stack.setup.js
deleted file mode 100644
index 820ad8c5c0e..00000000000
--- a/scripts/jest/stack.setup.js
+++ /dev/null
@@ -1,14 +0,0 @@
-'use strict';
-
-// We want to globally mock this but jest doesn't let us do that by default
-// for a file that already exists. So we have to explicitly mock it.
-jest.mock('ReactDOMFeatureFlags', () => {
-  const flags = require.requireActual('ReactDOMFeatureFlags');
-  return Object.assign({}, flags, {
-    useFiber: false,
-  });
-});
-
-// Error logging varies between Fiber and Stack;
-// Rather than fork dozens of tests, mock the error-logging file by default.
-jest.mock('ReactFiberErrorLogger');
diff --git a/scripts/rollup/modules.js b/scripts/rollup/modules.js
index 63636d3ae28..3c86653ae40 100644
--- a/scripts/rollup/modules.js
+++ b/scripts/rollup/modules.js
@@ -46,10 +46,7 @@ const fbjsModules = [
 ];
 
 const devOnlyFilesToStubOut = [
-  "'ReactDebugCurrentFrame'",
-  "'ReactComponentTreeHook'",
-  "'ReactPerf'",
-  "'ReactTestUtils'",
+  // TODO: figure out the ESM strategy
 ];
 
 const legacyModules = [
diff --git a/scripts/rollup/packaging.js b/scripts/rollup/packaging.js
index e5cf6f7eae6..caa09834c50 100644
--- a/scripts/rollup/packaging.js
+++ b/scripts/rollup/packaging.js
@@ -25,7 +25,7 @@ const facebookWWWSrcDependencies = [
 // these files need to be copied to the react-native build
 const reactNativeSrcDependencies = [
   // TODO: copy this to RN repository and delete from React
-  'src/renderers/shared/stack/PooledClass.js',
+  'src/renderers/native/PooledClass.js',
   'src/renderers/shared/fiber/isomorphic/ReactTypes.js',
   'src/renderers/native/ReactNativeTypes.js',
 ];
diff --git a/scripts/rollup/results.json b/scripts/rollup/results.json
index 18926d3dda1..12269dfbdeb 100644
--- a/scripts/rollup/results.json
+++ b/scripts/rollup/results.json
@@ -1,168 +1,168 @@
 {
   "bundleSizes": {
     "react.development.js (UMD_DEV)": {
-      "size": 65990,
-      "gzip": 16792
+      "size": 56348,
+      "gzip": 14331
     },
     "react.production.min.js (UMD_PROD)": {
-      "size": 6359,
-      "gzip": 2597
+      "size": 6010,
+      "gzip": 2510
     },
     "react.development.js (NODE_DEV)": {
-      "size": 56312,
-      "gzip": 14447
+      "size": 46827,
+      "gzip": 12290
     },
     "react.production.min.js (NODE_PROD)": {
       "size": 5382,
       "gzip": 2230
     },
     "React-dev.js (FB_DEV)": {
-      "size": 53513,
-      "gzip": 13663
+      "size": 44081,
+      "gzip": 11508
     },
     "React-prod.js (FB_PROD)": {
       "size": 25014,
       "gzip": 6703
     },
     "react-dom.development.js (UMD_DEV)": {
-      "size": 635358,
-      "gzip": 144868
+      "size": 607001,
+      "gzip": 136492
     },
     "react-dom.production.min.js (UMD_PROD)": {
-      "size": 108806,
-      "gzip": 34152
+      "size": 93693,
+      "gzip": 30033
     },
     "react-dom.development.js (NODE_DEV)": {
-      "size": 594767,
-      "gzip": 135242
+      "size": 580949,
+      "gzip": 133808
     },
     "react-dom.production.min.js (NODE_PROD)": {
-      "size": 112503,
-      "gzip": 35538
+      "size": 105524,
+      "gzip": 33161
     },
     "ReactDOMFiber-dev.js (FB_DEV)": {
-      "size": 591587,
-      "gzip": 134688
+      "size": 577839,
+      "gzip": 133294
     },
     "ReactDOMFiber-prod.js (FB_PROD)": {
-      "size": 425507,
-      "gzip": 95372
+      "size": 414529,
+      "gzip": 92865
     },
     "react-dom-test-utils.development.js (NODE_DEV)": {
-      "size": 53332,
-      "gzip": 13396
+      "size": 50829,
+      "gzip": 12937
     },
     "ReactTestUtils-dev.js (FB_DEV)": {
-      "size": 53124,
-      "gzip": 13357
+      "size": 50634,
+      "gzip": 12899
     },
     "react-dom-unstable-native-dependencies.development.js (UMD_DEV)": {
-      "size": 87907,
-      "gzip": 22195
+      "size": 77861,
+      "gzip": 19204
     },
     "react-dom-unstable-native-dependencies.production.min.js (UMD_PROD)": {
-      "size": 15149,
-      "gzip": 4910
+      "size": 11820,
+      "gzip": 4061
     },
     "react-dom-unstable-native-dependencies.development.js (NODE_DEV)": {
-      "size": 81355,
-      "gzip": 20240
+      "size": 80593,
+      "gzip": 19937
     },
     "react-dom-unstable-native-dependencies.production.min.js (NODE_PROD)": {
-      "size": 13926,
-      "gzip": 4403
+      "size": 13658,
+      "gzip": 4315
     },
     "ReactDOMUnstableNativeDependencies-dev.js (FB_DEV)": {
-      "size": 81054,
-      "gzip": 20200
+      "size": 80292,
+      "gzip": 19898
     },
     "ReactDOMUnstableNativeDependencies-prod.js (FB_PROD)": {
-      "size": 66066,
-      "gzip": 15736
+      "size": 65095,
+      "gzip": 15511
     },
     "react-dom-server.browser.development.js (UMD_DEV)": {
-      "size": 123203,
-      "gzip": 31145
+      "size": 123208,
+      "gzip": 30978
     },
     "react-dom-server.browser.production.min.js (UMD_PROD)": {
-      "size": 19874,
-      "gzip": 7592
+      "size": 14621,
+      "gzip": 5872
     },
     "react-dom-server.browser.development.js (NODE_DEV)": {
-      "size": 92379,
-      "gzip": 23736
+      "size": 100294,
+      "gzip": 26540
     },
     "react-dom-server.browser.production.min.js (NODE_PROD)": {
-      "size": 18930,
-      "gzip": 7264
+      "size": 14095,
+      "gzip": 5614
     },
     "ReactDOMServer-dev.js (FB_DEV)": {
-      "size": 91572,
-      "gzip": 23660
+      "size": 99487,
+      "gzip": 26440
     },
     "ReactDOMServer-prod.js (FB_PROD)": {
-      "size": 49652,
-      "gzip": 13866
+      "size": 42941,
+      "gzip": 12198
     },
     "react-dom-server.node.development.js (NODE_DEV)": {
-      "size": 95156,
-      "gzip": 24301
+      "size": 103071,
+      "gzip": 27107
     },
     "react-dom-server.node.production.min.js (NODE_PROD)": {
-      "size": 19986,
-      "gzip": 7613
+      "size": 15152,
+      "gzip": 5954
     },
     "react-art.development.js (UMD_DEV)": {
-      "size": 373742,
-      "gzip": 82778
+      "size": 373348,
+      "gzip": 82768
     },
     "react-art.production.min.js (UMD_PROD)": {
-      "size": 83498,
-      "gzip": 25838
+      "size": 83304,
+      "gzip": 25830
     },
     "react-art.development.js (NODE_DEV)": {
-      "size": 295131,
-      "gzip": 62776
+      "size": 294743,
+      "gzip": 62622
     },
     "react-art.production.min.js (NODE_PROD)": {
-      "size": 52520,
-      "gzip": 16419
+      "size": 52331,
+      "gzip": 16319
     },
     "ReactARTFiber-dev.js (FB_DEV)": {
-      "size": 294072,
-      "gzip": 62835
+      "size": 293684,
+      "gzip": 62680
     },
     "ReactARTFiber-prod.js (FB_PROD)": {
-      "size": 220269,
-      "gzip": 45845
+      "size": 219775,
+      "gzip": 45708
     },
     "ReactNativeFiber-dev.js (RN_DEV)": {
-      "size": 303055,
-      "gzip": 52683
+      "size": 275492,
+      "gzip": 48139
     },
     "ReactNativeFiber-prod.js (RN_PROD)": {
-      "size": 218403,
-      "gzip": 37966
+      "size": 215839,
+      "gzip": 37506
     },
     "react-test-renderer.development.js (NODE_DEV)": {
-      "size": 299567,
-      "gzip": 63217
+      "size": 298589,
+      "gzip": 62995
     },
     "ReactTestRendererFiber-dev.js (FB_DEV)": {
-      "size": 298493,
-      "gzip": 63294
+      "size": 297530,
+      "gzip": 63062
     },
     "react-test-renderer-shallow.development.js (NODE_DEV)": {
-      "size": 9556,
-      "gzip": 2379
+      "size": 9272,
+      "gzip": 2316
     },
     "ReactShallowRenderer-dev.js (FB_DEV)": {
-      "size": 9464,
-      "gzip": 2338
+      "size": 9180,
+      "gzip": 2271
     },
     "react-noop-renderer.development.js (NODE_DEV)": {
-      "size": 286842,
-      "gzip": 60085
+      "size": 286448,
+      "gzip": 59927
     },
     "react-dom-server.development.js (UMD_DEV)": {
       "size": 120897,
diff --git a/src/ReactVersion.js b/src/ReactVersion.js
index d06ad351a50..926067151fe 100644
--- a/src/ReactVersion.js
+++ b/src/ReactVersion.js
@@ -11,4 +11,5 @@
 
 'use strict';
 
+// TODO: convert this file to ESM (this currently breaks Node script).
 module.exports = '16.0.0-beta.5';
diff --git a/src/__mocks__/UIManager.js b/src/__mocks__/UIManager.js
index 28aa5304a6d..3391ea3f5d7 100644
--- a/src/__mocks__/UIManager.js
+++ b/src/__mocks__/UIManager.js
@@ -11,8 +11,8 @@
 
 // Mock of the Native Hooks
 
-const ReactNativeTagHandles = require('ReactNativeTagHandles');
-const invariant = require('fbjs/lib/invariant');
+import {reactTagIsNativeTopRootID} from 'ReactNativeTagHandles';
+import invariant from 'fbjs/lib/invariant';
 
 // Map of viewTag -> {children: [childTag], parent: ?parentTag}
 const roots = [];
@@ -20,7 +20,7 @@ let views = new Map();
 
 function autoCreateRoot(tag) {
   // Seriously, this is how we distinguish roots in RN.
-  if (!views.has(tag) && ReactNativeTagHandles.reactTagIsNativeTopRootID(tag)) {
+  if (!views.has(tag) && reactTagIsNativeTopRootID(tag)) {
     roots.push(tag);
     views.set(tag, {
       children: [],
@@ -203,4 +203,4 @@ var RCTUIManager = {
   },
 };
 
-module.exports = RCTUIManager;
+export default RCTUIManager;
diff --git a/src/isomorphic/ReactEntry.js b/src/isomorphic/ReactEntry.js
index e6ecd54048e..865522f4594 100644
--- a/src/isomorphic/ReactEntry.js
+++ b/src/isomorphic/ReactEntry.js
@@ -11,56 +11,57 @@
 
 'use strict';
 
-var ReactBaseClasses = require('ReactBaseClasses');
-var ReactChildren = require('ReactChildren');
-var ReactElement = require('ReactElement');
-var ReactVersion = require('ReactVersion');
-
-var onlyChild = require('onlyChild');
-
-var createElement = ReactElement.createElement;
-var createFactory = ReactElement.createFactory;
-var cloneElement = ReactElement.cloneElement;
-
-if (__DEV__) {
-  var ReactElementValidator = require('ReactElementValidator');
-  createElement = ReactElementValidator.createElement;
-  createFactory = ReactElementValidator.createFactory;
-  cloneElement = ReactElementValidator.cloneElement;
-}
+import {
+  Component,
+  PureComponent,
+  AsyncComponent as unstable_AsyncComponent,
+} from 'ReactBaseClasses';
+import {forEach, map, count, toArray, only} from 'ReactChildren';
+import {
+  createElement,
+  createFactory,
+  cloneElement,
+  isValidElement,
+} from 'ReactElement';
+import {
+  createElementWithValidation,
+  createFactoryWithValidation,
+  cloneElementWithValidation,
+} from 'ReactElementValidator';
+import ReactCurrentOwner from 'ReactCurrentOwner';
+import ReactVersion from 'ReactVersion';
+import * as ReactDebugCurrentFrame from 'ReactDebugCurrentFrame';
 
 var React = {
   Children: {
-    map: ReactChildren.map,
-    forEach: ReactChildren.forEach,
-    count: ReactChildren.count,
-    toArray: ReactChildren.toArray,
-    only: onlyChild,
+    map,
+    forEach,
+    count,
+    toArray,
+    only,
   },
 
-  Component: ReactBaseClasses.Component,
-  PureComponent: ReactBaseClasses.PureComponent,
-  unstable_AsyncComponent: ReactBaseClasses.AsyncComponent,
-
-  createElement: createElement,
-  cloneElement: cloneElement,
-  isValidElement: ReactElement.isValidElement,
+  Component,
+  PureComponent,
+  unstable_AsyncComponent,
 
-  createFactory: createFactory,
+  createElement: __DEV__ ? createElementWithValidation : createElement,
+  cloneElement: __DEV__ ? cloneElementWithValidation : cloneElement,
+  createFactory: __DEV__ ? createFactoryWithValidation : createFactory,
+  isValidElement: isValidElement,
 
   version: ReactVersion,
 
   __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: {
-    ReactCurrentOwner: require('ReactCurrentOwner'),
+    ReactCurrentOwner,
   },
 };
 
 if (__DEV__) {
   Object.assign(React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED, {
     // These should not be included in production.
-    ReactComponentTreeHook: require('ReactComponentTreeHook'),
-    ReactDebugCurrentFrame: require('ReactDebugCurrentFrame'),
+    ReactDebugCurrentFrame,
   });
 }
 
-module.exports = React;
+export default React;
diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index dd70a5d9684..6f99d80e960 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -11,15 +11,11 @@
 
 'use strict';
 
-var ReactElement = require('ReactElement');
-
-var emptyFunction = require('fbjs/lib/emptyFunction');
-var invariant = require('fbjs/lib/invariant');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var {getStackAddendum} = require('ReactDebugCurrentFrame');
-}
+import {isValidElement, cloneAndReplaceKey} from 'ReactElement';
+import emptyFunction from 'fbjs/lib/emptyFunction';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
+import {getStackAddendum} from 'ReactDebugCurrentFrame';
 
 var ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
 var FAUX_ITERATOR_SYMBOL = '@@iterator'; // Before Symbol spec.
@@ -274,7 +270,7 @@ function forEachSingleChild(bookKeeping, child, name) {
  * @param {function(*, int)} forEachFunc
  * @param {*} forEachContext Context for forEachContext.
  */
-function forEachChildren(children, forEachFunc, forEachContext) {
+export function forEach(children, forEachFunc, forEachContext) {
   if (children == null) {
     return children;
   }
@@ -300,8 +296,8 @@ function mapSingleChildIntoContext(bookKeeping, child, childKey) {
       emptyFunction.thatReturnsArgument,
     );
   } else if (mappedChild != null) {
-    if (ReactElement.isValidElement(mappedChild)) {
-      mappedChild = ReactElement.cloneAndReplaceKey(
+    if (isValidElement(mappedChild)) {
+      mappedChild = cloneAndReplaceKey(
         mappedChild,
         // Keep both the (mapped) and old keys if they differ, just as
         // traverseAllChildren used to do for objects as children
@@ -344,7 +340,7 @@ function mapIntoWithKeyPrefixInternal(children, array, prefix, func, context) {
  * @param {*} context Context for mapFunction.
  * @return {object} Object containing the ordered map of results.
  */
-function mapChildren(children, func, context) {
+export function map(children, func, context) {
   if (children == null) {
     return children;
   }
@@ -362,7 +358,7 @@ function mapChildren(children, func, context) {
  * @param {?*} children Children tree container.
  * @return {number} The number of children.
  */
-function countChildren(children, context) {
+export function count(children, context) {
   return traverseAllChildren(children, emptyFunction.thatReturnsNull, null);
 }
 
@@ -372,7 +368,7 @@ function countChildren(children, context) {
  *
  * See https://facebook.github.io/react/docs/react-api.html#react.children.toarray
  */
-function toArray(children) {
+export function toArray(children) {
   var result = [];
   mapIntoWithKeyPrefixInternal(
     children,
@@ -383,11 +379,24 @@ function toArray(children) {
   return result;
 }
 
-var ReactChildren = {
-  forEach: forEachChildren,
-  map: mapChildren,
-  count: countChildren,
-  toArray: toArray,
-};
-
-module.exports = ReactChildren;
+/**
+ * Returns the first child in a collection of children and verifies that there
+ * is only one child in the collection.
+ *
+ * See https://facebook.github.io/react/docs/react-api.html#react.children.only
+ *
+ * The current implementation of this function assumes that a single child gets
+ * passed without a wrapper, but the purpose of this helper function is to
+ * abstract away the particular structure of children.
+ *
+ * @param {?object} children Child collection structure.
+ * @return {ReactElement} The first and only `ReactElement` contained in the
+ * structure.
+ */
+export function only(children) {
+  invariant(
+    isValidElement(children),
+    'React.Children.only expected to receive a single React element child.',
+  );
+  return children;
+}
diff --git a/src/isomorphic/children/__tests__/ReactChildren-test.js b/src/isomorphic/children/__tests__/ReactChildren-test.js
index 9d97007cd17..d92a3b38473 100644
--- a/src/isomorphic/children/__tests__/ReactChildren-test.js
+++ b/src/isomorphic/children/__tests__/ReactChildren-test.js
@@ -11,8 +11,6 @@
 
 'use strict';
 
-const ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-
 describe('ReactChildren', () => {
   var React;
   var ReactTestUtils;
@@ -881,57 +879,55 @@ describe('ReactChildren', () => {
     );
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    describe('with fragments enabled', () => {
-      beforeEach(() => {
-        ReactFeatureFlags = require('ReactFeatureFlags');
-        ReactFeatureFlags.disableNewFiberFeatures = false;
-      });
+  describe('with fragments enabled', () => {
+    beforeEach(() => {
+      ReactFeatureFlags = require('ReactFeatureFlags');
+      ReactFeatureFlags.disableNewFiberFeatures = false;
+    });
 
-      it('warns for keys for arrays of elements in a fragment', () => {
-        spyOn(console, 'error');
-        class ComponentReturningArray extends React.Component {
-          render() {
-            return [<div />, <div />];
-          }
+    it('warns for keys for arrays of elements in a fragment', () => {
+      spyOn(console, 'error');
+      class ComponentReturningArray extends React.Component {
+        render() {
+          return [<div />, <div />];
         }
+      }
 
-        ReactTestUtils.renderIntoDocument(<ComponentReturningArray />);
+      ReactTestUtils.renderIntoDocument(<ComponentReturningArray />);
 
-        expectDev(console.error.calls.count()).toBe(1);
-        expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
-          'Warning: ' +
-            'Each child in an array or iterator should have a unique "key" prop.' +
-            ' See https://fb.me/react-warning-keys for more information.' +
-            '\n    in ComponentReturningArray (at **)',
-        );
-      });
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
+        'Warning: ' +
+          'Each child in an array or iterator should have a unique "key" prop.' +
+          ' See https://fb.me/react-warning-keys for more information.' +
+          '\n    in ComponentReturningArray (at **)',
+      );
+    });
 
-      it('does not warn when there are keys on  elements in a fragment', () => {
-        spyOn(console, 'error');
-        class ComponentReturningArray extends React.Component {
-          render() {
-            return [<div key="foo" />, <div key="bar" />];
-          }
+    it('does not warn when there are keys on  elements in a fragment', () => {
+      spyOn(console, 'error');
+      class ComponentReturningArray extends React.Component {
+        render() {
+          return [<div key="foo" />, <div key="bar" />];
         }
+      }
 
-        ReactTestUtils.renderIntoDocument(<ComponentReturningArray />);
+      ReactTestUtils.renderIntoDocument(<ComponentReturningArray />);
 
-        expectDev(console.error.calls.count()).toBe(0);
-      });
+      expectDev(console.error.calls.count()).toBe(0);
+    });
 
-      it('warns for keys for arrays at the top level', () => {
-        spyOn(console, 'error');
+    it('warns for keys for arrays at the top level', () => {
+      spyOn(console, 'error');
 
-        ReactTestUtils.renderIntoDocument([<div />, <div />]);
+      ReactTestUtils.renderIntoDocument([<div />, <div />]);
 
-        expectDev(console.error.calls.count()).toBe(1);
-        expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
-          'Warning: ' +
-            'Each child in an array or iterator should have a unique "key" prop.' +
-            ' See https://fb.me/react-warning-keys for more information.',
-        );
-      });
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
+        'Warning: ' +
+          'Each child in an array or iterator should have a unique "key" prop.' +
+          ' See https://fb.me/react-warning-keys for more information.',
+      );
     });
-  }
+  });
 });
diff --git a/src/isomorphic/children/onlyChild.js b/src/isomorphic/children/onlyChild.js
deleted file mode 100644
index efe815594c8..00000000000
--- a/src/isomorphic/children/onlyChild.js
+++ /dev/null
@@ -1,39 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule onlyChild
- */
-'use strict';
-
-var ReactElement = require('ReactElement');
-
-var invariant = require('fbjs/lib/invariant');
-
-/**
- * Returns the first child in a collection of children and verifies that there
- * is only one child in the collection.
- *
- * See https://facebook.github.io/react/docs/react-api.html#react.children.only
- *
- * The current implementation of this function assumes that a single child gets
- * passed without a wrapper, but the purpose of this helper function is to
- * abstract away the particular structure of children.
- *
- * @param {?object} children Child collection structure.
- * @return {ReactElement} The first and only `ReactElement` contained in the
- * structure.
- */
-function onlyChild(children) {
-  invariant(
-    ReactElement.isValidElement(children),
-    'React.Children.only expected to receive a single React element child.',
-  );
-  return children;
-}
-
-module.exports = onlyChild;
diff --git a/src/isomorphic/classic/element/ReactCurrentOwner.js b/src/isomorphic/classic/element/ReactCurrentOwner.js
index 3a12b523bd6..f42a1e4b8c7 100644
--- a/src/isomorphic/classic/element/ReactCurrentOwner.js
+++ b/src/isomorphic/classic/element/ReactCurrentOwner.js
@@ -12,7 +12,6 @@
 
 'use strict';
 
-import type {ReactInstance} from 'ReactInstanceType';
 import type {Fiber} from 'ReactFiber';
 
 /**
@@ -26,7 +25,7 @@ var ReactCurrentOwner = {
    * @internal
    * @type {ReactComponent}
    */
-  current: (null: null | ReactInstance | Fiber),
+  current: (null: null | Fiber),
 };
 
-module.exports = ReactCurrentOwner;
+export default ReactCurrentOwner;
diff --git a/src/isomorphic/classic/element/ReactDebugCurrentFrame.js b/src/isomorphic/classic/element/ReactDebugCurrentFrame.js
index fad26ea1556..cb053bc3645 100644
--- a/src/isomorphic/classic/element/ReactDebugCurrentFrame.js
+++ b/src/isomorphic/classic/element/ReactDebugCurrentFrame.js
@@ -12,19 +12,21 @@
 
 'use strict';
 
-const ReactDebugCurrentFrame = {};
+let getCurrentStack: null | (() => string | null) = null;
 
-if (__DEV__) {
-  // Component that is being worked on
-  ReactDebugCurrentFrame.getCurrentStack = (null: null | (() => string | null));
+export function setCurrentStackImplementation(
+  impl: null | (() => string | null),
+) {
+  if (__DEV__) {
+    getCurrentStack = impl;
+  }
+}
 
-  ReactDebugCurrentFrame.getStackAddendum = function(): string | null {
-    const impl = ReactDebugCurrentFrame.getCurrentStack;
-    if (impl) {
-      return impl();
+export function getStackAddendum(): string | null {
+  if (__DEV__) {
+    if (getCurrentStack) {
+      return getCurrentStack();
     }
-    return null;
-  };
+  }
+  return null;
 }
-
-module.exports = ReactDebugCurrentFrame;
diff --git a/src/isomorphic/classic/element/ReactElement.js b/src/isomorphic/classic/element/ReactElement.js
index 38fe85378e6..d7cf2bb5c81 100644
--- a/src/isomorphic/classic/element/ReactElement.js
+++ b/src/isomorphic/classic/element/ReactElement.js
@@ -11,12 +11,10 @@
 
 'use strict';
 
-var ReactCurrentOwner = require('ReactCurrentOwner');
-var hasOwnProperty = Object.prototype.hasOwnProperty;
+import ReactCurrentOwner from 'ReactCurrentOwner';
+import warning from 'fbjs/lib/warning';
 
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+var hasOwnProperty = Object.prototype.hasOwnProperty;
 
 // The Symbol used to tag the ReactElement type. If there is no native Symbol
 // nor polyfill, then a plain number is used for performance.
@@ -179,7 +177,7 @@ var ReactElement = function(type, key, ref, self, source, owner, props) {
  * Create and return a new ReactElement of the given type.
  * See https://facebook.github.io/react/docs/react-api.html#createelement
  */
-ReactElement.createElement = function(type, config, children) {
+export function createElement(type, config, children) {
   var propName;
 
   // Reserved names are extracted
@@ -265,14 +263,14 @@ ReactElement.createElement = function(type, config, children) {
     ReactCurrentOwner.current,
     props,
   );
-};
+}
 
 /**
  * Return a function that produces ReactElements of a given type.
  * See https://facebook.github.io/react/docs/react-api.html#createfactory
  */
-ReactElement.createFactory = function(type) {
-  var factory = ReactElement.createElement.bind(null, type);
+export function createFactory(type) {
+  var factory = createElement.bind(null, type);
   // Expose the type on the factory and the prototype so that it can be
   // easily accessed on elements. E.g. `<Foo />.type === Foo`.
   // This should not be named `constructor` since this may not be the function
@@ -280,9 +278,9 @@ ReactElement.createFactory = function(type) {
   // Legacy hook TODO: Warn if this is accessed
   factory.type = type;
   return factory;
-};
+}
 
-ReactElement.cloneAndReplaceKey = function(oldElement, newKey) {
+export function cloneAndReplaceKey(oldElement, newKey) {
   var newElement = ReactElement(
     oldElement.type,
     newKey,
@@ -294,13 +292,13 @@ ReactElement.cloneAndReplaceKey = function(oldElement, newKey) {
   );
 
   return newElement;
-};
+}
 
 /**
  * Clone and return a new ReactElement using element as the starting point.
  * See https://facebook.github.io/react/docs/react-api.html#cloneelement
  */
-ReactElement.cloneElement = function(element, config, children) {
+export function cloneElement(element, config, children) {
   var propName;
 
   // Original props are copied
@@ -363,7 +361,7 @@ ReactElement.cloneElement = function(element, config, children) {
   }
 
   return ReactElement(element.type, key, ref, self, source, owner, props);
-};
+}
 
 /**
  * Verifies the object is a ReactElement.
@@ -372,12 +370,10 @@ ReactElement.cloneElement = function(element, config, children) {
  * @return {boolean} True if `object` is a valid component.
  * @final
  */
-ReactElement.isValidElement = function(object) {
+export function isValidElement(object) {
   return (
     typeof object === 'object' &&
     object !== null &&
     object.$$typeof === REACT_ELEMENT_TYPE
   );
-};
-
-module.exports = ReactElement;
+}
diff --git a/src/isomorphic/classic/element/ReactElementValidator.js b/src/isomorphic/classic/element/ReactElementValidator.js
index 8d2f6e55395..e18f675b59f 100644
--- a/src/isomorphic/classic/element/ReactElementValidator.js
+++ b/src/isomorphic/classic/element/ReactElementValidator.js
@@ -18,17 +18,16 @@
 
 'use strict';
 
-var ReactCurrentOwner = require('ReactCurrentOwner');
-var ReactElement = require('ReactElement');
+import ReactCurrentOwner from 'ReactCurrentOwner';
+import {isValidElement, createElement, cloneElement} from 'ReactElement';
+import checkPropTypes from 'prop-types/checkPropTypes';
+import lowPriorityWarning from 'lowPriorityWarning';
+import {getStackAddendum} from 'ReactDebugCurrentFrame';
+import warning from 'fbjs/lib/warning';
+import describeComponentFrame from 'describeComponentFrame';
+import getComponentName from 'getComponentName';
 
 if (__DEV__) {
-  var checkPropTypes = require('prop-types/checkPropTypes');
-  var lowPriorityWarning = require('lowPriorityWarning');
-  var ReactDebugCurrentFrame = require('ReactDebugCurrentFrame');
-  var warning = require('fbjs/lib/warning');
-  var describeComponentFrame = require('describeComponentFrame');
-  var getComponentName = require('getComponentName');
-
   var currentlyValidatingElement = null;
 
   var getDisplayName = function(element: ?ReactElement): string {
@@ -43,7 +42,7 @@ if (__DEV__) {
     }
   };
 
-  var getStackAddendum = function(): string {
+  var getElementStackAddendum = function(): string {
     var stack = '';
     if (currentlyValidatingElement) {
       var name = getDisplayName(currentlyValidatingElement);
@@ -54,7 +53,7 @@ if (__DEV__) {
         owner && getComponentName(owner),
       );
     }
-    stack += ReactDebugCurrentFrame.getStackAddendum() || '';
+    stack += getStackAddendum() || '';
     return stack;
   };
 }
@@ -151,7 +150,7 @@ function validateExplicitKey(element, parentType) {
         '%s%s See https://fb.me/react-warning-keys for more information.%s',
       currentComponentErrorInfo,
       childOwner,
-      getStackAddendum(),
+      getElementStackAddendum(),
     );
   }
   currentlyValidatingElement = null;
@@ -173,11 +172,11 @@ function validateChildKeys(node, parentType) {
   if (Array.isArray(node)) {
     for (var i = 0; i < node.length; i++) {
       var child = node[i];
-      if (ReactElement.isValidElement(child)) {
+      if (isValidElement(child)) {
         validateExplicitKey(child, parentType);
       }
     }
-  } else if (ReactElement.isValidElement(node)) {
+  } else if (isValidElement(node)) {
     // This element was passed in a valid location.
     if (node._store) {
       node._store.validated = true;
@@ -192,7 +191,7 @@ function validateChildKeys(node, parentType) {
         var iterator = iteratorFn.call(node);
         var step;
         while (!(step = iterator.next()).done) {
-          if (ReactElement.isValidElement(step.value)) {
+          if (isValidElement(step.value)) {
             validateExplicitKey(step.value, parentType);
           }
         }
@@ -226,7 +225,13 @@ function validatePropTypes(element) {
 
   if (propTypes) {
     currentlyValidatingElement = element;
-    checkPropTypes(propTypes, element.props, 'prop', name, getStackAddendum);
+    checkPropTypes(
+      propTypes,
+      element.props,
+      'prop',
+      name,
+      getElementStackAddendum,
+    );
     currentlyValidatingElement = null;
   }
   if (typeof componentClass.getDefaultProps === 'function') {
@@ -238,100 +243,96 @@ function validatePropTypes(element) {
   }
 }
 
-var ReactElementValidator = {
-  createElement: function(type, props, children) {
-    var validType = typeof type === 'string' || typeof type === 'function';
-    // We warn in this case but don't throw. We expect the element creation to
-    // succeed and there will likely be errors in render.
-    if (!validType) {
-      var info = '';
-      if (
-        type === undefined ||
-        (typeof type === 'object' &&
-          type !== null &&
-          Object.keys(type).length === 0)
-      ) {
-        info +=
-          ' You likely forgot to export your component from the file ' +
-          "it's defined in.";
-      }
+export function createElementWithValidation(type, props, children) {
+  var validType = typeof type === 'string' || typeof type === 'function';
+  // We warn in this case but don't throw. We expect the element creation to
+  // succeed and there will likely be errors in render.
+  if (!validType) {
+    var info = '';
+    if (
+      type === undefined ||
+      (typeof type === 'object' &&
+        type !== null &&
+        Object.keys(type).length === 0)
+    ) {
+      info +=
+        ' You likely forgot to export your component from the file ' +
+        "it's defined in.";
+    }
 
-      var sourceInfo = getSourceInfoErrorAddendum(props);
-      if (sourceInfo) {
-        info += sourceInfo;
-      } else {
-        info += getDeclarationErrorAddendum();
-      }
+    var sourceInfo = getSourceInfoErrorAddendum(props);
+    if (sourceInfo) {
+      info += sourceInfo;
+    } else {
+      info += getDeclarationErrorAddendum();
+    }
 
-      info += ReactDebugCurrentFrame.getStackAddendum() || '';
+    info += getStackAddendum() || '';
 
-      warning(
-        false,
-        'React.createElement: type is invalid -- expected a string (for ' +
-          'built-in components) or a class/function (for composite ' +
-          'components) but got: %s.%s',
-        type == null ? type : typeof type,
-        info,
-      );
-    }
+    warning(
+      false,
+      'React.createElement: type is invalid -- expected a string (for ' +
+        'built-in components) or a class/function (for composite ' +
+        'components) but got: %s.%s',
+      type == null ? type : typeof type,
+      info,
+    );
+  }
 
-    var element = ReactElement.createElement.apply(this, arguments);
+  var element = createElement.apply(this, arguments);
 
-    // The result can be nullish if a mock or a custom function is used.
-    // TODO: Drop this when these are no longer allowed as the type argument.
-    if (element == null) {
-      return element;
-    }
+  // The result can be nullish if a mock or a custom function is used.
+  // TODO: Drop this when these are no longer allowed as the type argument.
+  if (element == null) {
+    return element;
+  }
 
-    // Skip key warning if the type isn't valid since our key validation logic
-    // doesn't expect a non-string/function type and can throw confusing errors.
-    // We don't want exception behavior to differ between dev and prod.
-    // (Rendering will throw with a helpful message and as soon as the type is
-    // fixed, the key warnings will appear.)
-    if (validType) {
-      for (var i = 2; i < arguments.length; i++) {
-        validateChildKeys(arguments[i], type);
-      }
+  // Skip key warning if the type isn't valid since our key validation logic
+  // doesn't expect a non-string/function type and can throw confusing errors.
+  // We don't want exception behavior to differ between dev and prod.
+  // (Rendering will throw with a helpful message and as soon as the type is
+  // fixed, the key warnings will appear.)
+  if (validType) {
+    for (var i = 2; i < arguments.length; i++) {
+      validateChildKeys(arguments[i], type);
     }
+  }
 
-    validatePropTypes(element);
+  validatePropTypes(element);
 
-    return element;
-  },
-
-  createFactory: function(type) {
-    var validatedFactory = ReactElementValidator.createElement.bind(null, type);
-    // Legacy hook TODO: Warn if this is accessed
-    validatedFactory.type = type;
-
-    if (__DEV__) {
-      Object.defineProperty(validatedFactory, 'type', {
-        enumerable: false,
-        get: function() {
-          lowPriorityWarning(
-            false,
-            'Factory.type is deprecated. Access the class directly ' +
-              'before passing it to createFactory.',
-          );
-          Object.defineProperty(this, 'type', {
-            value: type,
-          });
-          return type;
-        },
-      });
-    }
+  return element;
+}
 
-    return validatedFactory;
-  },
+export function createFactoryWithValidation(type) {
+  var validatedFactory = createElementWithValidation.bind(null, type);
+  // Legacy hook TODO: Warn if this is accessed
+  validatedFactory.type = type;
 
-  cloneElement: function(element, props, children) {
-    var newElement = ReactElement.cloneElement.apply(this, arguments);
-    for (var i = 2; i < arguments.length; i++) {
-      validateChildKeys(arguments[i], newElement.type);
-    }
-    validatePropTypes(newElement);
-    return newElement;
-  },
-};
+  if (__DEV__) {
+    Object.defineProperty(validatedFactory, 'type', {
+      enumerable: false,
+      get: function() {
+        lowPriorityWarning(
+          false,
+          'Factory.type is deprecated. Access the class directly ' +
+            'before passing it to createFactory.',
+        );
+        Object.defineProperty(this, 'type', {
+          value: type,
+        });
+        return type;
+      },
+    });
+  }
 
-module.exports = ReactElementValidator;
+  return validatedFactory;
+}
+
+export function cloneElementWithValidation(element, props, children) {
+  var newElement = cloneElement.apply(this, arguments);
+  for (var i = 2; i < arguments.length; i++) {
+    validateChildKeys(arguments[i], newElement.type);
+  }
+  validatePropTypes(newElement);
+  return newElement;
+}
diff --git a/src/isomorphic/classic/element/__tests__/ReactElement-test.js b/src/isomorphic/classic/element/__tests__/ReactElement-test.js
index e0f0047c47e..af21beb8c62 100644
--- a/src/isomorphic/classic/element/__tests__/ReactElement-test.js
+++ b/src/isomorphic/classic/element/__tests__/ReactElement-test.js
@@ -14,7 +14,6 @@
 var React;
 var ReactDOM;
 var ReactTestUtils;
-var ReactDOMFeatureFlags;
 
 describe('ReactElement', () => {
   var ComponentClass;
@@ -31,7 +30,6 @@ describe('ReactElement', () => {
     React = require('react');
     ReactDOM = require('react-dom');
     ReactTestUtils = require('react-dom/test-utils');
-    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
     // NOTE: We're explicitly not using JSX here. This is intended to test
     // classic JS without JSX.
     ComponentClass = class extends React.Component {
@@ -237,12 +235,7 @@ describe('ReactElement', () => {
     var instance = ReactTestUtils.renderIntoDocument(
       React.createElement(Wrapper),
     );
-
-    if (ReactDOMFeatureFlags.useFiber) {
-      expect(element._owner.stateNode).toBe(instance);
-    } else {
-      expect(element._owner.getPublicInstance()).toBe(instance);
-    }
+    expect(element._owner.stateNode).toBe(instance);
   });
 
   it('merges an additional argument onto the children prop', () => {
diff --git a/src/isomorphic/hooks/ReactComponentTreeHook.js b/src/isomorphic/hooks/ReactComponentTreeHook.js
deleted file mode 100644
index 08c107e5791..00000000000
--- a/src/isomorphic/hooks/ReactComponentTreeHook.js
+++ /dev/null
@@ -1,398 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @flow
- * @providesModule ReactComponentTreeHook
- */
-
-'use strict';
-
-var ReactCurrentOwner = require('ReactCurrentOwner');
-var invariant = require('fbjs/lib/invariant');
-var describeComponentFrame = require('describeComponentFrame');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
-import type {ReactElement, Source} from 'ReactElementType';
-import type {DebugID} from 'ReactInstanceType';
-
-function isNative(fn) {
-  // Based on isNative() from Lodash
-  var funcToString = Function.prototype.toString;
-  var reIsNative = RegExp(
-    '^' +
-      funcToString
-        // Take an example native function source for comparison
-        .call(Object.prototype.hasOwnProperty)
-        // Strip regex characters so we can use it for regex
-        .replace(/[\\^$.*+?()[\]{}|]/g, '\\$&')
-        // Remove hasOwnProperty from the template to make it generic
-        .replace(
-          /hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g,
-          '$1.*?',
-        ) +
-      '$',
-  );
-  try {
-    var source = funcToString.call(fn);
-    return reIsNative.test(source);
-  } catch (err) {
-    return false;
-  }
-}
-
-var canUseCollections =
-  // Array.from
-  typeof Array.from === 'function' &&
-  // Map
-  typeof Map === 'function' &&
-  isNative(Map) &&
-  // Map.prototype.keys
-  Map.prototype != null &&
-  typeof Map.prototype.keys === 'function' &&
-  isNative(Map.prototype.keys) &&
-  // Set
-  typeof Set === 'function' &&
-  isNative(Set) &&
-  // Set.prototype.keys
-  Set.prototype != null &&
-  typeof Set.prototype.keys === 'function' &&
-  isNative(Set.prototype.keys);
-
-var setItem;
-var getItem;
-var removeItem;
-var getItemIDs;
-var addRoot;
-var removeRoot;
-var getRootIDs;
-
-if (canUseCollections) {
-  var itemMap = new Map();
-  var rootIDSet = new Set();
-
-  setItem = function(id, item) {
-    itemMap.set(id, item);
-  };
-  getItem = function(id) {
-    return itemMap.get(id);
-  };
-  removeItem = function(id) {
-    itemMap.delete(id);
-  };
-  getItemIDs = function() {
-    return Array.from(itemMap.keys());
-  };
-
-  addRoot = function(id) {
-    rootIDSet.add(id);
-  };
-  removeRoot = function(id) {
-    rootIDSet.delete(id);
-  };
-  getRootIDs = function() {
-    return Array.from(rootIDSet.keys());
-  };
-} else {
-  var itemByKey = {};
-  var rootByKey = {};
-
-  // Use non-numeric keys to prevent V8 performance issues:
-  // https://github.com/facebook/react/pull/7232
-  var getKeyFromID = function(id: DebugID): string {
-    return '.' + id;
-  };
-  var getIDFromKey = function(key: string): DebugID {
-    return parseInt(key.substr(1), 10);
-  };
-
-  setItem = function(id, item) {
-    var key = getKeyFromID(id);
-    itemByKey[key] = item;
-  };
-  getItem = function(id) {
-    var key = getKeyFromID(id);
-    return itemByKey[key];
-  };
-  removeItem = function(id) {
-    var key = getKeyFromID(id);
-    delete itemByKey[key];
-  };
-  getItemIDs = function() {
-    return Object.keys(itemByKey).map(getIDFromKey);
-  };
-
-  addRoot = function(id) {
-    var key = getKeyFromID(id);
-    rootByKey[key] = true;
-  };
-  removeRoot = function(id) {
-    var key = getKeyFromID(id);
-    delete rootByKey[key];
-  };
-  getRootIDs = function() {
-    return Object.keys(rootByKey).map(getIDFromKey);
-  };
-}
-
-var unmountedIDs: Array<DebugID> = [];
-
-function purgeDeep(id) {
-  var item = getItem(id);
-  if (item) {
-    var {childIDs} = item;
-    removeItem(id);
-    childIDs.forEach(purgeDeep);
-  }
-}
-
-function getDisplayName(element: ?ReactElement): string {
-  if (element == null) {
-    return '#empty';
-  } else if (typeof element === 'string' || typeof element === 'number') {
-    return '#text';
-  } else if (typeof element.type === 'string') {
-    return element.type;
-  } else {
-    return element.type.displayName || element.type.name || 'Unknown';
-  }
-}
-
-function describeID(id: DebugID): string {
-  const name = ReactComponentTreeHook.getDisplayName(id);
-  const element = ReactComponentTreeHook.getElement(id);
-  const ownerID = ReactComponentTreeHook.getOwnerID(id);
-  let ownerName;
-
-  if (ownerID) {
-    ownerName = ReactComponentTreeHook.getDisplayName(ownerID);
-  }
-  warning(
-    element,
-    'ReactComponentTreeHook: Missing React element for debugID %s when ' +
-      'building stack',
-    id,
-  );
-  return describeComponentFrame(
-    name || '',
-    element && element._source,
-    ownerName || '',
-  );
-}
-
-var ReactComponentTreeHook = {
-  onSetChildren(id: DebugID, nextChildIDs: Array<DebugID>): void {
-    var item = getItem(id);
-    invariant(item, 'Item must have been set');
-    item.childIDs = nextChildIDs;
-
-    for (var i = 0; i < nextChildIDs.length; i++) {
-      var nextChildID = nextChildIDs[i];
-      var nextChild = getItem(nextChildID);
-      invariant(
-        nextChild,
-        'Expected hook events to fire for the child ' +
-          'before its parent includes it in onSetChildren().',
-      );
-      invariant(
-        nextChild.childIDs != null ||
-          typeof nextChild.element !== 'object' ||
-          nextChild.element == null,
-        'Expected onSetChildren() to fire for a container child ' +
-          'before its parent includes it in onSetChildren().',
-      );
-      invariant(
-        nextChild.isMounted,
-        'Expected onMountComponent() to fire for the child ' +
-          'before its parent includes it in onSetChildren().',
-      );
-      if (nextChild.parentID == null) {
-        nextChild.parentID = id;
-        // TODO: This shouldn't be necessary but mounting a new root during in
-        // componentWillMount currently causes not-yet-mounted components to
-        // be purged from our tree data so their parent id is missing.
-      }
-      invariant(
-        nextChild.parentID === id,
-        'Expected onBeforeMountComponent() parent and onSetChildren() to ' +
-          'be consistent (%s has parents %s and %s).',
-        nextChildID,
-        nextChild.parentID,
-        id,
-      );
-    }
-  },
-
-  onBeforeMountComponent(
-    id: DebugID,
-    element: ReactElement,
-    parentID: DebugID,
-  ): void {
-    var item = {
-      element,
-      parentID,
-      text: null,
-      childIDs: [],
-      isMounted: false,
-      updateCount: 0,
-    };
-    setItem(id, item);
-  },
-
-  onBeforeUpdateComponent(id: DebugID, element: ReactElement): void {
-    var item = getItem(id);
-    if (!item || !item.isMounted) {
-      // We may end up here as a result of setState() in componentWillUnmount().
-      // In this case, ignore the element.
-      return;
-    }
-    item.element = element;
-  },
-
-  onMountComponent(id: DebugID): void {
-    var item = getItem(id);
-    invariant(item, 'Item must have been set');
-    item.isMounted = true;
-    var isRoot = item.parentID === 0;
-    if (isRoot) {
-      addRoot(id);
-    }
-  },
-
-  onUpdateComponent(id: DebugID): void {
-    var item = getItem(id);
-    if (!item || !item.isMounted) {
-      // We may end up here as a result of setState() in componentWillUnmount().
-      // In this case, ignore the element.
-      return;
-    }
-    item.updateCount++;
-  },
-
-  onUnmountComponent(id: DebugID): void {
-    var item = getItem(id);
-    if (item) {
-      // We need to check if it exists.
-      // `item` might not exist if it is inside an error boundary, and a sibling
-      // error boundary child threw while mounting. Then this instance never
-      // got a chance to mount, but it still gets an unmounting event during
-      // the error boundary cleanup.
-      item.isMounted = false;
-      var isRoot = item.parentID === 0;
-      if (isRoot) {
-        removeRoot(id);
-      }
-    }
-    unmountedIDs.push(id);
-  },
-
-  purgeUnmountedComponents(): void {
-    if (ReactComponentTreeHook._preventPurging) {
-      // Should only be used for testing.
-      return;
-    }
-
-    for (var i = 0; i < unmountedIDs.length; i++) {
-      var id = unmountedIDs[i];
-      purgeDeep(id);
-    }
-    unmountedIDs.length = 0;
-  },
-
-  isMounted(id: DebugID): boolean {
-    var item = getItem(id);
-    return item ? item.isMounted : false;
-  },
-
-  getCurrentStackAddendum(): string {
-    var info = '';
-    var currentOwner = ReactCurrentOwner.current;
-    if (currentOwner) {
-      invariant(
-        typeof currentOwner.tag !== 'number',
-        'Fiber owners should not show up in Stack stack traces.',
-      );
-      if (typeof currentOwner._debugID === 'number') {
-        info += ReactComponentTreeHook.getStackAddendumByID(
-          currentOwner._debugID,
-        );
-      }
-    }
-    return info;
-  },
-
-  getStackAddendumByID(id: ?DebugID): string {
-    var info = '';
-    while (id) {
-      info += describeID(id);
-      id = ReactComponentTreeHook.getParentID(id);
-    }
-    return info;
-  },
-
-  getChildIDs(id: DebugID): Array<DebugID> {
-    var item = getItem(id);
-    return item ? item.childIDs : [];
-  },
-
-  getDisplayName(id: DebugID): ?string {
-    var element = ReactComponentTreeHook.getElement(id);
-    if (!element) {
-      return null;
-    }
-    return getDisplayName(element);
-  },
-
-  getElement(id: DebugID): ?ReactElement {
-    var item = getItem(id);
-    return item ? item.element : null;
-  },
-
-  getOwnerID(id: DebugID): ?DebugID {
-    var element = ReactComponentTreeHook.getElement(id);
-    if (!element || !element._owner) {
-      return null;
-    }
-    return element._owner._debugID;
-  },
-
-  getParentID(id: DebugID): ?DebugID {
-    var item = getItem(id);
-    return item ? item.parentID : null;
-  },
-
-  getSource(id: DebugID): ?Source {
-    var item = getItem(id);
-    var element = item ? item.element : null;
-    var source = element != null ? element._source : null;
-    return source;
-  },
-
-  getText(id: DebugID): ?string {
-    var element = ReactComponentTreeHook.getElement(id);
-    if (typeof element === 'string') {
-      return element;
-    } else if (typeof element === 'number') {
-      return '' + element;
-    } else {
-      return null;
-    }
-  },
-
-  getUpdateCount(id: DebugID): number {
-    var item = getItem(id);
-    return item ? item.updateCount : 0;
-  },
-
-  getRootIDs,
-  getRegisteredIDs: getItemIDs,
-};
-
-module.exports = ReactComponentTreeHook;
diff --git a/src/isomorphic/modern/class/ReactBaseClasses.js b/src/isomorphic/modern/class/ReactBaseClasses.js
index f2b3a6c6d6a..e4a88d42868 100644
--- a/src/isomorphic/modern/class/ReactBaseClasses.js
+++ b/src/isomorphic/modern/class/ReactBaseClasses.js
@@ -11,16 +11,15 @@
 
 'use strict';
 
-var ReactNoopUpdateQueue = require('ReactNoopUpdateQueue');
-
-var emptyObject = require('fbjs/lib/emptyObject');
-var invariant = require('fbjs/lib/invariant');
-var lowPriorityWarning = require('lowPriorityWarning');
+import ReactNoopUpdateQueue from 'ReactNoopUpdateQueue';
+import emptyObject from 'fbjs/lib/emptyObject';
+import invariant from 'fbjs/lib/invariant';
+import lowPriorityWarning from 'lowPriorityWarning';
 
 /**
  * Base class helpers for the updating state of a component.
  */
-function ReactComponent(props, context, updater) {
+export function Component(props, context, updater) {
   this.props = props;
   this.context = context;
   this.refs = emptyObject;
@@ -29,7 +28,7 @@ function ReactComponent(props, context, updater) {
   this.updater = updater || ReactNoopUpdateQueue;
 }
 
-ReactComponent.prototype.isReactComponent = {};
+Component.prototype.isReactComponent = {};
 
 /**
  * Sets a subset of the state. Always use this to mutate
@@ -56,7 +55,7 @@ ReactComponent.prototype.isReactComponent = {};
  * @final
  * @protected
  */
-ReactComponent.prototype.setState = function(partialState, callback) {
+Component.prototype.setState = function(partialState, callback) {
   invariant(
     typeof partialState === 'object' ||
       typeof partialState === 'function' ||
@@ -81,7 +80,7 @@ ReactComponent.prototype.setState = function(partialState, callback) {
  * @final
  * @protected
  */
-ReactComponent.prototype.forceUpdate = function(callback) {
+Component.prototype.forceUpdate = function(callback) {
   this.updater.enqueueForceUpdate(this, callback, 'forceUpdate');
 };
 
@@ -104,7 +103,7 @@ if (__DEV__) {
     ],
   };
   var defineDeprecationWarning = function(methodName, info) {
-    Object.defineProperty(ReactComponent.prototype, methodName, {
+    Object.defineProperty(Component.prototype, methodName, {
       get: function() {
         lowPriorityWarning(
           false,
@@ -126,8 +125,8 @@ if (__DEV__) {
 /**
  * Base class helpers for the updating state of a component.
  */
-function ReactPureComponent(props, context, updater) {
-  // Duplicated from ReactComponent.
+export function PureComponent(props, context, updater) {
+  // Duplicated from Component.
   this.props = props;
   this.context = context;
   this.refs = emptyObject;
@@ -137,15 +136,15 @@ function ReactPureComponent(props, context, updater) {
 }
 
 function ComponentDummy() {}
-ComponentDummy.prototype = ReactComponent.prototype;
-var pureComponentPrototype = (ReactPureComponent.prototype = new ComponentDummy());
-pureComponentPrototype.constructor = ReactPureComponent;
+ComponentDummy.prototype = Component.prototype;
+var pureComponentPrototype = (PureComponent.prototype = new ComponentDummy());
+pureComponentPrototype.constructor = PureComponent;
 // Avoid an extra prototype jump for these methods.
-Object.assign(pureComponentPrototype, ReactComponent.prototype);
+Object.assign(pureComponentPrototype, Component.prototype);
 pureComponentPrototype.isPureReactComponent = true;
 
-function ReactAsyncComponent(props, context, updater) {
-  // Duplicated from ReactComponent.
+export function AsyncComponent(props, context, updater) {
+  // Duplicated from Component.
   this.props = props;
   this.context = context;
   this.refs = emptyObject;
@@ -154,17 +153,11 @@ function ReactAsyncComponent(props, context, updater) {
   this.updater = updater || ReactNoopUpdateQueue;
 }
 
-var asyncComponentPrototype = (ReactAsyncComponent.prototype = new ComponentDummy());
-asyncComponentPrototype.constructor = ReactAsyncComponent;
+var asyncComponentPrototype = (AsyncComponent.prototype = new ComponentDummy());
+asyncComponentPrototype.constructor = AsyncComponent;
 // Avoid an extra prototype jump for these methods.
-Object.assign(asyncComponentPrototype, ReactComponent.prototype);
+Object.assign(asyncComponentPrototype, Component.prototype);
 asyncComponentPrototype.unstable_isAsyncReactComponent = true;
 asyncComponentPrototype.render = function() {
   return this.props.children;
 };
-
-module.exports = {
-  Component: ReactComponent,
-  PureComponent: ReactPureComponent,
-  AsyncComponent: ReactAsyncComponent,
-};
diff --git a/src/isomorphic/modern/class/ReactNoopUpdateQueue.js b/src/isomorphic/modern/class/ReactNoopUpdateQueue.js
index e3822644506..f0aa03f0430 100644
--- a/src/isomorphic/modern/class/ReactNoopUpdateQueue.js
+++ b/src/isomorphic/modern/class/ReactNoopUpdateQueue.js
@@ -11,9 +11,7 @@
 
 'use strict';
 
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import warning from 'fbjs/lib/warning';
 
 function warnNoop(publicInstance, callerName) {
   if (__DEV__) {
@@ -109,4 +107,4 @@ var ReactNoopUpdateQueue = {
   },
 };
 
-module.exports = ReactNoopUpdateQueue;
+export default ReactNoopUpdateQueue;
diff --git a/src/node_modules/react-dom/index.js b/src/node_modules/react-dom/index.js
index 9e3e32c735b..509750de3b7 100644
--- a/src/node_modules/react-dom/index.js
+++ b/src/node_modules/react-dom/index.js
@@ -6,9 +6,4 @@
 
 'use strict';
 
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-var useFiber = ReactDOMFeatureFlags.useFiber;
-
-module.exports = useFiber
- ? require('ReactDOMFiberEntry')
- : require('ReactDOMStackEntry');
+module.exports = require('ReactDOMFiberEntry');
diff --git a/src/node_modules/react-dom/server.browser.js b/src/node_modules/react-dom/server.browser.js
index 8c08b1d6768..bc357430978 100644
--- a/src/node_modules/react-dom/server.browser.js
+++ b/src/node_modules/react-dom/server.browser.js
@@ -6,9 +6,4 @@
 
 'use strict';
 
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-var useFiber = ReactDOMFeatureFlags.useFiber;
-
-module.exports = useFiber
-  ? require('ReactDOMServerBrowserEntry')
-  : require('ReactDOMServerStackEntry');
+module.exports = require('ReactDOMServerBrowserEntry');
diff --git a/src/node_modules/react-dom/server.js b/src/node_modules/react-dom/server.js
index fa6285bfefc..f19a4b36a91 100644
--- a/src/node_modules/react-dom/server.js
+++ b/src/node_modules/react-dom/server.js
@@ -6,9 +6,4 @@
 
 'use strict';
 
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-var useFiber = ReactDOMFeatureFlags.useFiber;
-
-module.exports = useFiber
-  ? require('ReactDOMServerNodeEntry')
-  : require('ReactDOMServerStackEntry');
+module.exports = require('ReactDOMServerNodeEntry');
diff --git a/src/renderers/__tests__/ReactComponent-test.js b/src/renderers/__tests__/ReactComponent-test.js
index a5f5ce287f6..b1007b688c1 100644
--- a/src/renderers/__tests__/ReactComponent-test.js
+++ b/src/renderers/__tests__/ReactComponent-test.js
@@ -16,8 +16,6 @@ var ReactDOM;
 var ReactDOMServer;
 var ReactTestUtils;
 
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-
 describe('ReactComponent', () => {
   function normalizeCodeLocInfo(str) {
     return str && str.replace(/\(at .+?:\d+\)/g, '(at **)');
@@ -299,21 +297,11 @@ describe('ReactComponent', () => {
       'outer componentDidMount',
       'start update',
       // Previous (equivalent) refs get cleared
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Fiber renders first, resets refs later
-            'inner 1 render',
-            'inner 2 render',
-            'ref 1 got null',
-            'ref 2 got null',
-          ]
-        : [
-            // Stack resets refs before rendering
-            'ref 1 got null',
-            'inner 1 render',
-            'ref 2 got null',
-            'inner 2 render',
-          ]),
+      // Fiber renders first, resets refs later
+      'inner 1 render',
+      'inner 2 render',
+      'ref 1 got null',
+      'ref 2 got null',
       'inner 1 componentDidUpdate',
       'ref 1 got instance 1',
       'inner 2 componentDidUpdate',
@@ -408,8 +396,7 @@ describe('ReactComponent', () => {
       'Objects are not valid as a React child (found: object with keys ' +
         '{x, y, z}). If you meant to render a collection of children, use ' +
         'an array instead.' +
-        // Fiber gives a slightly better stack with the nearest host components
-        (ReactDOMFeatureFlags.useFiber ? '\n    in div (at **)' : ''),
+        '\n    in div (at **)',
     );
   });
 
@@ -436,8 +423,7 @@ describe('ReactComponent', () => {
       'Objects are not valid as a React child (found: object with keys ' +
         '{a, b, c}). If you meant to render a collection of children, use ' +
         'an array instead.\n' +
-        // Fiber gives a slightly better stack with the nearest host components
-        (ReactDOMFeatureFlags.useFiber ? '    in div (at **)\n' : '') +
+        '    in div (at **)\n' +
         '    in Foo (at **)',
     );
   });
@@ -460,8 +446,7 @@ describe('ReactComponent', () => {
       'Objects are not valid as a React child (found: object with keys ' +
         '{x, y, z}). If you meant to render a collection of children, use ' +
         'an array instead.' +
-        // Fiber gives a slightly better stack with the nearest host components
-        (ReactDOMFeatureFlags.useFiber ? '\n    in div (at **)' : ''),
+        '\n    in div (at **)',
     );
   });
 
@@ -488,83 +473,80 @@ describe('ReactComponent', () => {
       'Objects are not valid as a React child (found: object with keys ' +
         '{a, b, c}). If you meant to render a collection of children, use ' +
         'an array instead.\n' +
-        // Fiber gives a slightly better stack with the nearest host components
-        (ReactDOMFeatureFlags.useFiber ? '    in div (at **)\n' : '') +
+        '    in div (at **)\n' +
         '    in Foo (at **)',
     );
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    describe('with new features', () => {
-      beforeEach(() => {
-        require('ReactFeatureFlags').disableNewFiberFeatures = false;
-      });
+  describe('with new features', () => {
+    beforeEach(() => {
+      require('ReactFeatureFlags').disableNewFiberFeatures = false;
+    });
 
-      it('warns on function as a return value from a function', () => {
-        function Foo() {
-          return Foo;
-        }
-        spyOn(console, 'error');
-        var container = document.createElement('div');
-        ReactDOM.render(<Foo />, container);
-        expectDev(console.error.calls.count()).toBe(1);
-        expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
-          'Warning: Functions are not valid as a React child. This may happen if ' +
-            'you return a Component instead of <Component /> from render. ' +
-            'Or maybe you meant to call this function rather than return it.\n' +
-            '    in Foo (at **)',
-        );
-      });
+    it('warns on function as a return value from a function', () => {
+      function Foo() {
+        return Foo;
+      }
+      spyOn(console, 'error');
+      var container = document.createElement('div');
+      ReactDOM.render(<Foo />, container);
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
+        'Warning: Functions are not valid as a React child. This may happen if ' +
+          'you return a Component instead of <Component /> from render. ' +
+          'Or maybe you meant to call this function rather than return it.\n' +
+          '    in Foo (at **)',
+      );
+    });
 
-      it('warns on function as a return value from a class', () => {
-        class Foo extends React.Component {
-          render() {
-            return Foo;
-          }
+    it('warns on function as a return value from a class', () => {
+      class Foo extends React.Component {
+        render() {
+          return Foo;
         }
-        spyOn(console, 'error');
-        var container = document.createElement('div');
-        ReactDOM.render(<Foo />, container);
-        expectDev(console.error.calls.count()).toBe(1);
-        expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
-          'Warning: Functions are not valid as a React child. This may happen if ' +
-            'you return a Component instead of <Component /> from render. ' +
-            'Or maybe you meant to call this function rather than return it.\n' +
-            '    in Foo (at **)',
-        );
-      });
+      }
+      spyOn(console, 'error');
+      var container = document.createElement('div');
+      ReactDOM.render(<Foo />, container);
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
+        'Warning: Functions are not valid as a React child. This may happen if ' +
+          'you return a Component instead of <Component /> from render. ' +
+          'Or maybe you meant to call this function rather than return it.\n' +
+          '    in Foo (at **)',
+      );
+    });
 
-      it('warns on function as a child to host component', () => {
-        function Foo() {
-          return <div><span>{Foo}</span></div>;
-        }
-        spyOn(console, 'error');
-        var container = document.createElement('div');
-        ReactDOM.render(<Foo />, container);
-        expectDev(console.error.calls.count()).toBe(1);
-        expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
-          'Warning: Functions are not valid as a React child. This may happen if ' +
-            'you return a Component instead of <Component /> from render. ' +
-            'Or maybe you meant to call this function rather than return it.\n' +
-            '    in span (at **)\n' +
-            '    in div (at **)\n' +
-            '    in Foo (at **)',
-        );
-      });
+    it('warns on function as a child to host component', () => {
+      function Foo() {
+        return <div><span>{Foo}</span></div>;
+      }
+      spyOn(console, 'error');
+      var container = document.createElement('div');
+      ReactDOM.render(<Foo />, container);
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
+        'Warning: Functions are not valid as a React child. This may happen if ' +
+          'you return a Component instead of <Component /> from render. ' +
+          'Or maybe you meant to call this function rather than return it.\n' +
+          '    in span (at **)\n' +
+          '    in div (at **)\n' +
+          '    in Foo (at **)',
+      );
+    });
 
-      it('does not warn for function-as-a-child that gets resolved', () => {
-        function Bar(props) {
-          return props.children();
-        }
-        function Foo() {
-          return <Bar>{() => 'Hello'}</Bar>;
-        }
-        spyOn(console, 'error');
-        var container = document.createElement('div');
-        ReactDOM.render(<Foo />, container);
-        expect(container.innerHTML).toBe('Hello');
-        expectDev(console.error.calls.count()).toBe(0);
-      });
+    it('does not warn for function-as-a-child that gets resolved', () => {
+      function Bar(props) {
+        return props.children();
+      }
+      function Foo() {
+        return <Bar>{() => 'Hello'}</Bar>;
+      }
+      spyOn(console, 'error');
+      var container = document.createElement('div');
+      ReactDOM.render(<Foo />, container);
+      expect(container.innerHTML).toBe('Hello');
+      expectDev(console.error.calls.count()).toBe(0);
     });
-  }
+  });
 });
diff --git a/src/renderers/__tests__/ReactComponentTreeHook-test.js b/src/renderers/__tests__/ReactComponentTreeHook-test.js
deleted file mode 100644
index c7ca3644ecd..00000000000
--- a/src/renderers/__tests__/ReactComponentTreeHook-test.js
+++ /dev/null
@@ -1,2217 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @emails react-core
- */
-
-'use strict';
-
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-var describeStack = ReactDOMFeatureFlags.useFiber ? describe.skip : describe;
-
-describe('ReactComponentTreeHook', () => {
-  var React;
-  var ReactDOM;
-  var ReactDOMServer;
-  var ReactInstanceMap;
-  var ReactComponentTreeHook;
-  var ReactDebugCurrentFiber;
-  var ReactComponentTreeTestUtils;
-
-  beforeEach(() => {
-    jest.resetModules();
-
-    React = require('react');
-    ReactDOM = require('react-dom');
-    ReactDOMServer = require('react-dom/server');
-    ReactInstanceMap = require('ReactInstanceMap');
-    ReactDebugCurrentFiber = require('ReactDebugCurrentFiber');
-    ReactComponentTreeHook = require('ReactComponentTreeHook');
-    ReactComponentTreeTestUtils = require('ReactComponentTreeTestUtils');
-  });
-
-  // This is the only part used both by Stack and Fiber.
-  describe('stack addenda', () => {
-    it('gets created', () => {
-      function getAddendum(element) {
-        var addendum = ReactDOMFeatureFlags.useFiber
-          ? ReactDebugCurrentFiber.getCurrentFiberStackAddendum() || ''
-          : ReactComponentTreeHook.getCurrentStackAddendum();
-        return addendum.replace(/\(at .+?:\d+\)/g, '(at **)');
-      }
-
-      function Anon() {
-        return null;
-      }
-      Object.defineProperty(Anon, 'name', {
-        value: null,
-      });
-      // function Orange() {
-      //   return null;
-      // }
-
-      expectDev(getAddendum()).toBe('');
-      // expectDev(getAddendum(<div />)).toBe('\n    in div (at **)');
-      // expectDev(getAddendum(<Anon />)).toBe('\n    in Unknown (at **)');
-      // expectDev(getAddendum(<Orange />)).toBe('\n    in Orange (at **)');
-      // expectDev(getAddendum(React.createElement(Orange))).toBe(
-      //   '\n    in Orange',
-      // );
-
-      var renders = 0;
-      //var rOwnedByQ;
-
-      function Q() {
-        return /*rOwnedByQ =*/ React.createElement(R);
-      }
-      function R() {
-        return <div><S /></div>;
-      }
-      class S extends React.Component {
-        componentDidMount() {
-          // Check that the parent path is still fetched when only S itself is on
-          // the stack.
-          this.forceUpdate();
-        }
-        render() {
-          expectDev(getAddendum()).toBe(
-            '\n    in S (at **)' +
-              '\n    in div (at **)' +
-              '\n    in R (created by Q)' +
-              '\n    in Q (at **)',
-          );
-          expectDev(getAddendum(<span />)).toBe(
-            // '\n    in span (at **)' +
-            '\n    in S (at **)' +
-              '\n    in div (at **)' +
-              '\n    in R (created by Q)' +
-              '\n    in Q (at **)',
-          );
-          expectDev(getAddendum(React.createElement('span'))).toBe(
-            // '\n    in span (created by S)' +
-            '\n    in S (at **)' +
-              '\n    in div (at **)' +
-              '\n    in R (created by Q)' +
-              '\n    in Q (at **)',
-          );
-          renders++;
-          return null;
-        }
-      }
-      ReactDOM.render(<Q />, document.createElement('div'));
-      expectDev(renders).toBe(2);
-
-      // Make sure owner is fetched for the top element too.
-      // expectDev(getAddendum(rOwnedByQ)).toBe('\n    in R (created by Q)');
-    });
-
-    // These are features and regression tests that only affect
-    // the Stack implementation of the stack addendum.
-    if (!ReactDOMFeatureFlags.useFiber) {
-      it('can be retrieved by ID', () => {
-        function getAddendum(id) {
-          var addendum = ReactComponentTreeHook.getStackAddendumByID(id);
-          return addendum.replace(/\(at .+?:\d+\)/g, '(at **)');
-        }
-
-        class Q extends React.Component {
-          render() {
-            return null;
-          }
-        }
-
-        var q = ReactDOM.render(<Q />, document.createElement('div'));
-        expectDev(getAddendum(ReactInstanceMap.get(q)._debugID)).toBe(
-          '\n    in Q (at **)',
-        );
-
-        spyOn(console, 'error');
-        getAddendum(-17);
-        expectDev(console.error.calls.count()).toBe(1);
-        expectDev(console.error.calls.argsFor(0)[0]).toBe(
-          'Warning: ReactComponentTreeHook: Missing React element for ' +
-            'debugID -17 when building stack',
-        );
-      });
-
-      it('is created during mounting', () => {
-        // https://github.com/facebook/react/issues/7187
-        var el = document.createElement('div');
-        var portalEl = document.createElement('div');
-        class Foo extends React.Component {
-          componentWillMount() {
-            ReactDOM.render(<div />, portalEl);
-          }
-          render() {
-            return <div><div /></div>;
-          }
-        }
-        ReactDOM.render(<Foo />, el);
-      });
-
-      it('is created when calling renderToString during render', () => {
-        // https://github.com/facebook/react/issues/7190
-        var el = document.createElement('div');
-        class Foo extends React.Component {
-          render() {
-            return (
-              <div>
-                <div>
-                  {ReactDOMServer.renderToString(<div />)}
-                </div>
-              </div>
-            );
-          }
-        }
-        ReactDOM.render(<Foo />, el);
-      });
-    }
-  });
-
-  // The rest of this file is not relevant for Fiber.
-  // TODO: remove tests below when we delete Stack.
-
-  function assertTreeMatches(pairs) {
-    if (!Array.isArray(pairs[0])) {
-      pairs = [pairs];
-    }
-
-    var node = document.createElement('div');
-    var currentElement;
-    var rootInstance;
-
-    class Wrapper extends React.Component {
-      render() {
-        rootInstance = ReactInstanceMap.get(this);
-        return currentElement;
-      }
-    }
-
-    function expectWrapperTreeToEqual(expectedTree, andStayMounted) {
-      ReactComponentTreeTestUtils.expectTree(rootInstance._debugID, {
-        displayName: 'Wrapper',
-        children: expectedTree ? [expectedTree] : [],
-      });
-      var rootDisplayNames = ReactComponentTreeTestUtils.getRootDisplayNames();
-      var registeredDisplayNames = ReactComponentTreeTestUtils.getRegisteredDisplayNames();
-      if (!expectedTree) {
-        expectDev(rootDisplayNames).toEqual([]);
-        expectDev(registeredDisplayNames).toEqual([]);
-      } else if (andStayMounted) {
-        expectDev(rootDisplayNames).toContain('Wrapper');
-        expectDev(registeredDisplayNames).toContain('Wrapper');
-      }
-    }
-
-    // Mount once, render updates, then unmount.
-    // Ensure the tree is correct on every step.
-    pairs.forEach(([element, expectedTree]) => {
-      currentElement = element;
-
-      // Mount a new tree or update the existing tree.
-      ReactDOM.render(<Wrapper />, node);
-      expectWrapperTreeToEqual(expectedTree, true);
-
-      // Purging should have no effect
-      // on the tree we expect to see.
-      ReactComponentTreeHook.purgeUnmountedComponents();
-      expectWrapperTreeToEqual(expectedTree, true);
-    });
-
-    // Unmounting the root node should purge
-    // the whole subtree automatically.
-    ReactDOM.unmountComponentAtNode(node);
-    expectWrapperTreeToEqual(null);
-  }
-
-  describeStack('mount', () => {
-    it('uses displayName or Unknown for classic components', () => {
-      class Foo extends React.Component {
-        render() {
-          return null;
-        }
-      }
-
-      Foo.displayName = 'Bar';
-
-      class Baz extends React.Component {
-        render() {
-          return null;
-        }
-      }
-
-      class Qux extends React.Component {
-        render() {
-          return null;
-        }
-      }
-
-      delete Qux.displayName;
-
-      var element = <div><Foo /><Baz /><Qux /></div>;
-      var tree = {
-        displayName: 'div',
-        children: [
-          {
-            displayName: 'Bar',
-            children: [],
-          },
-          {
-            displayName: 'Baz',
-            children: [],
-          },
-          {
-            displayName: 'Unknown',
-            children: [],
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('uses displayName, name, or ReactComponent for modern components', () => {
-      class Foo extends React.Component {
-        render() {
-          return null;
-        }
-      }
-      Foo.displayName = 'Bar';
-      class Baz extends React.Component {
-        render() {
-          return null;
-        }
-      }
-      class Qux extends React.Component {
-        render() {
-          return null;
-        }
-      }
-      delete Qux.name;
-
-      var element = <div><Foo /><Baz /><Qux /></div>;
-      var tree = {
-        displayName: 'div',
-        element,
-        children: [
-          {
-            displayName: 'Bar',
-            children: [],
-          },
-          {
-            displayName: 'Baz',
-            children: [],
-          },
-          {
-            // Note: Ideally fallback name should be consistent (e.g. "Unknown")
-            displayName: 'ReactComponent',
-            children: [],
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('uses displayName, name, or Object for factory components', () => {
-      function Foo() {
-        return {
-          render() {
-            return null;
-          },
-        };
-      }
-      Foo.displayName = 'Bar';
-      function Baz() {
-        return {
-          render() {
-            return null;
-          },
-        };
-      }
-      function Qux() {
-        return {
-          render() {
-            return null;
-          },
-        };
-      }
-      delete Qux.name;
-
-      var element = <div><Foo /><Baz /><Qux /></div>;
-      var tree = {
-        displayName: 'div',
-        element,
-        children: [
-          {
-            displayName: 'Bar',
-            children: [],
-          },
-          {
-            displayName: 'Baz',
-            children: [],
-          },
-          {
-            displayName: 'Unknown',
-            children: [],
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('uses displayName, name, or StatelessComponent for functional components', () => {
-      function Foo() {
-        return null;
-      }
-      Foo.displayName = 'Bar';
-      function Baz() {
-        return null;
-      }
-      function Qux() {
-        return null;
-      }
-      delete Qux.name;
-
-      var element = <div><Foo /><Baz /><Qux /></div>;
-      var tree = {
-        displayName: 'div',
-        element,
-        children: [
-          {
-            displayName: 'Bar',
-            children: [],
-          },
-          {
-            displayName: 'Baz',
-            children: [],
-          },
-          {
-            displayName: 'Unknown',
-            children: [],
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('reports a host tree correctly', () => {
-      var element = (
-        <div>
-          <p>
-            <span>
-              Hi!
-            </span>
-            Wow.
-          </p>
-          <hr />
-        </div>
-      );
-      var tree = {
-        displayName: 'div',
-        children: [
-          {
-            displayName: 'p',
-            children: [
-              {
-                displayName: 'span',
-                children: [
-                  {
-                    displayName: '#text',
-                    text: 'Hi!',
-                  },
-                ],
-              },
-              {
-                displayName: '#text',
-                text: 'Wow.',
-              },
-            ],
-          },
-          {
-            displayName: 'hr',
-            element: <hr />,
-            children: [],
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('reports a simple tree with composites correctly', () => {
-      class Foo extends React.Component {
-        render() {
-          return <div />;
-        }
-      }
-
-      var element = <Foo />;
-      var tree = {
-        displayName: 'Foo',
-        element,
-        children: [
-          {
-            displayName: 'div',
-            element: <div />,
-            children: [],
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('reports a tree with composites correctly', () => {
-      class Qux extends React.Component {
-        render() {
-          return null;
-        }
-      }
-
-      function Foo() {
-        return {
-          render() {
-            return <Qux />;
-          },
-        };
-      }
-      function Bar({children}) {
-        return <h1>{children}</h1>;
-      }
-      class Baz extends React.Component {
-        render() {
-          return (
-            <div>
-              <Foo />
-              <Bar>
-                <span>Hi,</span>
-                Mom
-              </Bar>
-              <a href="#">Click me.</a>
-            </div>
-          );
-        }
-      }
-
-      var element = <Baz />;
-      var tree = {
-        displayName: 'Baz',
-        element,
-        children: [
-          {
-            displayName: 'div',
-            children: [
-              {
-                displayName: 'Foo',
-                element: <Foo />,
-                children: [
-                  {
-                    displayName: 'Qux',
-                    element: <Qux />,
-                    children: [],
-                  },
-                ],
-              },
-              {
-                displayName: 'Bar',
-                children: [
-                  {
-                    displayName: 'h1',
-                    children: [
-                      {
-                        displayName: 'span',
-                        children: [
-                          {
-                            displayName: '#text',
-                            element: 'Hi,',
-                            text: 'Hi,',
-                          },
-                        ],
-                      },
-                      {
-                        displayName: '#text',
-                        text: 'Mom',
-                        element: 'Mom',
-                      },
-                    ],
-                  },
-                ],
-              },
-              {
-                displayName: 'a',
-                children: [
-                  {
-                    displayName: '#text',
-                    text: 'Click me.',
-                    element: 'Click me.',
-                  },
-                ],
-              },
-            ],
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('ignores null children', () => {
-      class Foo extends React.Component {
-        render() {
-          return null;
-        }
-      }
-      var element = <Foo />;
-      var tree = {
-        displayName: 'Foo',
-        children: [],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('ignores false children', () => {
-      class Foo extends React.Component {
-        render() {
-          return false;
-        }
-      }
-      var element = <Foo />;
-      var tree = {
-        displayName: 'Foo',
-        children: [],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('reports text nodes as children', () => {
-      var element = <div>{'1'}{2}</div>;
-      var tree = {
-        displayName: 'div',
-        element,
-        children: [
-          {
-            displayName: '#text',
-            text: '1',
-          },
-          {
-            displayName: '#text',
-            text: '2',
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('reports a single text node as a child', () => {
-      var element = <div>{'1'}</div>;
-      var tree = {
-        displayName: 'div',
-        element,
-        children: [
-          {
-            displayName: '#text',
-            text: '1',
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('reports a single number node as a child', () => {
-      var element = <div>{42}</div>;
-      var tree = {
-        displayName: 'div',
-        element,
-        children: [
-          {
-            displayName: '#text',
-            text: '42',
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('reports a zero as a child', () => {
-      var element = <div>{0}</div>;
-      var tree = {
-        displayName: 'div',
-        element,
-        children: [
-          {
-            displayName: '#text',
-            text: '0',
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('skips empty nodes for multiple children', () => {
-      function Foo() {
-        return <div />;
-      }
-      var element = (
-        <div>
-          {'hi'}
-          {false}
-          {42}
-          {null}
-          <Foo />
-        </div>
-      );
-      var tree = {
-        displayName: 'div',
-        element,
-        children: [
-          {
-            displayName: '#text',
-            text: 'hi',
-            element: 'hi',
-          },
-          {
-            displayName: '#text',
-            text: '42',
-            element: 42,
-          },
-          {
-            displayName: 'Foo',
-            element: <Foo />,
-            children: [
-              {
-                displayName: 'div',
-                element: <div />,
-                children: [],
-              },
-            ],
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('reports html content as no children', () => {
-      var element = <div dangerouslySetInnerHTML={{__html: 'Bye.'}} />;
-      var tree = {
-        displayName: 'div',
-        children: [],
-      };
-      assertTreeMatches([element, tree]);
-    });
-  });
-
-  describeStack('update', () => {
-    describe('host component', () => {
-      it('updates text of a single text child', () => {
-        var elementBefore = <div>Hi.</div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-          ],
-        };
-
-        var elementAfter = <div>Bye.</div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Bye.',
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from no children to a single text child', () => {
-        var elementBefore = <div />;
-        var treeBefore = {
-          displayName: 'div',
-          children: [],
-        };
-
-        var elementAfter = <div>Hi.</div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a single text child to no children', () => {
-        var elementBefore = <div>Hi.</div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-          ],
-        };
-
-        var elementAfter = <div />;
-        var treeAfter = {
-          displayName: 'div',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from html content to a single text child', () => {
-        var elementBefore = <div dangerouslySetInnerHTML={{__html: 'Hi.'}} />;
-        var treeBefore = {
-          displayName: 'div',
-          children: [],
-        };
-
-        var elementAfter = <div>Hi.</div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a single text child to html content', () => {
-        var elementBefore = <div>Hi.</div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-          ],
-        };
-
-        var elementAfter = <div dangerouslySetInnerHTML={{__html: 'Hi.'}} />;
-        var treeAfter = {
-          displayName: 'div',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from no children to multiple text children', () => {
-        var elementBefore = <div />;
-        var treeBefore = {
-          displayName: 'div',
-          children: [],
-        };
-
-        var elementAfter = <div>{'Hi.'}{'Bye.'}</div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-            {
-              displayName: '#text',
-              text: 'Bye.',
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from multiple text children to no children', () => {
-        var elementBefore = <div>{'Hi.'}{'Bye.'}</div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-            {
-              displayName: '#text',
-              text: 'Bye.',
-            },
-          ],
-        };
-
-        var elementAfter = <div />;
-        var treeAfter = {
-          displayName: 'div',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from html content to multiple text children', () => {
-        var elementBefore = <div dangerouslySetInnerHTML={{__html: 'Hi.'}} />;
-        var treeBefore = {
-          displayName: 'div',
-          children: [],
-        };
-
-        var elementAfter = <div>{'Hi.'}{'Bye.'}</div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-            {
-              displayName: '#text',
-              text: 'Bye.',
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from multiple text children to html content', () => {
-        var elementBefore = <div>{'Hi.'}{'Bye.'}</div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-            {
-              displayName: '#text',
-              text: 'Bye.',
-            },
-          ],
-        };
-
-        var elementAfter = <div dangerouslySetInnerHTML={{__html: 'Hi.'}} />;
-        var treeAfter = {
-          displayName: 'div',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from html content to no children', () => {
-        var elementBefore = <div dangerouslySetInnerHTML={{__html: 'Hi.'}} />;
-        var treeBefore = {
-          displayName: 'div',
-          children: [],
-        };
-
-        var elementAfter = <div />;
-        var treeAfter = {
-          displayName: 'div',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from no children to html content', () => {
-        var elementBefore = <div />;
-        var treeBefore = {
-          displayName: 'div',
-          children: [],
-        };
-
-        var elementAfter = <div dangerouslySetInnerHTML={{__html: 'Hi.'}} />;
-        var treeAfter = {
-          displayName: 'div',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from one text child to multiple text children', () => {
-        var elementBefore = <div>Hi.</div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-          ],
-        };
-
-        var elementAfter = <div>{'Hi.'}{'Bye.'}</div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-            {
-              displayName: '#text',
-              text: 'Bye.',
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from multiple text children to one text child', () => {
-        var elementBefore = <div>{'Hi.'}{'Bye.'}</div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-            {
-              displayName: '#text',
-              text: 'Bye.',
-            },
-          ],
-        };
-
-        var elementAfter = <div>Hi.</div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-          ],
-        };
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates text nodes when reordering', () => {
-        var elementBefore = <div>{'Hi.'}{'Bye.'}</div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-            {
-              displayName: '#text',
-              text: 'Bye.',
-            },
-          ],
-        };
-
-        var elementAfter = <div>{'Bye.'}{'Hi.'}</div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'Bye.',
-            },
-            {
-              displayName: '#text',
-              text: 'Hi.',
-            },
-          ],
-        };
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates host nodes when reordering with keys', () => {
-        var elementBefore = (
-          <div>
-            <div key="a">Hi.</div>
-            <div key="b">Bye.</div>
-          </div>
-        );
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'div',
-              children: [
-                {
-                  displayName: '#text',
-                  text: 'Hi.',
-                },
-              ],
-            },
-            {
-              displayName: 'div',
-              children: [
-                {
-                  displayName: '#text',
-                  text: 'Bye.',
-                },
-              ],
-            },
-          ],
-        };
-
-        var elementAfter = (
-          <div>
-            <div key="b">Bye.</div>
-            <div key="a">Hi.</div>
-          </div>
-        );
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'div',
-              children: [
-                {
-                  displayName: '#text',
-                  text: 'Bye.',
-                },
-              ],
-            },
-            {
-              displayName: 'div',
-              children: [
-                {
-                  displayName: '#text',
-                  text: 'Hi.',
-                },
-              ],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates host nodes when reordering without keys', () => {
-        var elementBefore = (
-          <div>
-            <div>Hi.</div>
-            <div>Bye.</div>
-          </div>
-        );
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'div',
-              children: [
-                {
-                  displayName: '#text',
-                  text: 'Hi.',
-                },
-              ],
-            },
-            {
-              displayName: 'div',
-              children: [
-                {
-                  displayName: '#text',
-                  text: 'Bye.',
-                },
-              ],
-            },
-          ],
-        };
-
-        var elementAfter = (
-          <div>
-            <div>Bye.</div>
-            <div>Hi.</div>
-          </div>
-        );
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'div',
-              children: [
-                {
-                  displayName: '#text',
-                  text: 'Bye.',
-                },
-              ],
-            },
-            {
-              displayName: 'div',
-              children: [
-                {
-                  displayName: '#text',
-                  text: 'Hi.',
-                },
-              ],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates a single composite child of a different type', () => {
-        function Foo() {
-          return null;
-        }
-
-        function Bar() {
-          return null;
-        }
-
-        var elementBefore = <div><Foo /></div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'Foo',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <div><Bar /></div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'Bar',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates a single composite child of the same type', () => {
-        function Foo({children}) {
-          return children;
-        }
-
-        var elementBefore = <div><Foo><div /></Foo></div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'Foo',
-              children: [
-                {
-                  displayName: 'div',
-                  children: [],
-                },
-              ],
-            },
-          ],
-        };
-
-        var elementAfter = <div><Foo><span /></Foo></div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'Foo',
-              children: [
-                {
-                  displayName: 'span',
-                  children: [],
-                },
-              ],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from no children to a single composite child', () => {
-        function Foo() {
-          return null;
-        }
-
-        var elementBefore = <div />;
-        var treeBefore = {
-          displayName: 'div',
-          children: [],
-        };
-
-        var elementAfter = <div><Foo /></div>;
-        var treeAfter = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'Foo',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a single composite child to no children', () => {
-        function Foo() {
-          return null;
-        }
-
-        var elementBefore = <div><Foo /></div>;
-        var treeBefore = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'Foo',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <div />;
-        var treeAfter = {
-          displayName: 'div',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates mixed children', () => {
-        function Foo() {
-          return <div />;
-        }
-        var element1 = (
-          <div>
-            {'hi'}
-            {false}
-            {42}
-            {null}
-            <Foo />
-          </div>
-        );
-        var tree1 = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: '#text',
-              text: 'hi',
-            },
-            {
-              displayName: '#text',
-              text: '42',
-            },
-            {
-              displayName: 'Foo',
-              children: [
-                {
-                  displayName: 'div',
-                  children: [],
-                },
-              ],
-            },
-          ],
-        };
-
-        var element2 = (
-          <div>
-            <Foo />
-            {false}
-            {'hi'}
-            {null}
-          </div>
-        );
-        var tree2 = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'Foo',
-              children: [
-                {
-                  displayName: 'div',
-                  children: [],
-                },
-              ],
-            },
-            {
-              displayName: '#text',
-              text: 'hi',
-            },
-          ],
-        };
-
-        var element3 = (
-          <div>
-            <Foo />
-          </div>
-        );
-        var tree3 = {
-          displayName: 'div',
-          children: [
-            {
-              displayName: 'Foo',
-              children: [
-                {
-                  displayName: 'div',
-                  children: [],
-                },
-              ],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [element1, tree1],
-          [element2, tree2],
-          [element3, tree3],
-        ]);
-      });
-    });
-
-    describe('functional component', () => {
-      it('updates with a host child', () => {
-        function Foo({children}) {
-          return children;
-        }
-
-        var elementBefore = <Foo><div /></Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'div',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <Foo><span /></Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'span',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from null to a host child', () => {
-        function Foo({children}) {
-          return children;
-        }
-
-        var elementBefore = <Foo>{null}</Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [],
-        };
-
-        var elementAfter = <Foo><div /></Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'div',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a host child to null', () => {
-        function Foo({children}) {
-          return children;
-        }
-
-        var elementBefore = <Foo><div /></Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'div',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <Foo>{null}</Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a host child to a composite child', () => {
-        function Bar() {
-          return null;
-        }
-
-        function Foo({children}) {
-          return children;
-        }
-
-        var elementBefore = <Foo><div /></Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'div',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <Foo><Bar /></Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'Bar',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a composite child to a host child', () => {
-        function Bar() {
-          return null;
-        }
-
-        function Foo({children}) {
-          return children;
-        }
-
-        var elementBefore = <Foo><Bar /></Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'Bar',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <Foo><div /></Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'div',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from null to a composite child', () => {
-        function Bar() {
-          return null;
-        }
-
-        function Foo({children}) {
-          return children;
-        }
-
-        var elementBefore = <Foo>{null}</Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [],
-        };
-
-        var elementAfter = <Foo><Bar /></Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'Bar',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a composite child to null', () => {
-        function Bar() {
-          return null;
-        }
-
-        function Foo({children}) {
-          return children;
-        }
-
-        var elementBefore = <Foo><Bar /></Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'Bar',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <Foo>{null}</Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-    });
-
-    describe('class component', () => {
-      it('updates with a host child', () => {
-        class Foo extends React.Component {
-          render() {
-            return this.props.children;
-          }
-        }
-
-        var elementBefore = <Foo><div /></Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'div',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <Foo><span /></Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'span',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from null to a host child', () => {
-        class Foo extends React.Component {
-          render() {
-            return this.props.children;
-          }
-        }
-
-        var elementBefore = <Foo>{null}</Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [],
-        };
-
-        var elementAfter = <Foo><div /></Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'div',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a host child to null', () => {
-        class Foo extends React.Component {
-          render() {
-            return this.props.children;
-          }
-        }
-
-        var elementBefore = <Foo><div /></Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'div',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <Foo>{null}</Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a host child to a composite child', () => {
-        class Bar extends React.Component {
-          render() {
-            return null;
-          }
-        }
-
-        class Foo extends React.Component {
-          render() {
-            return this.props.children;
-          }
-        }
-
-        var elementBefore = <Foo><div /></Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'div',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <Foo><Bar /></Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'Bar',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a composite child to a host child', () => {
-        class Bar extends React.Component {
-          render() {
-            return null;
-          }
-        }
-
-        class Foo extends React.Component {
-          render() {
-            return this.props.children;
-          }
-        }
-
-        var elementBefore = <Foo><Bar /></Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'Bar',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <Foo><div /></Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'div',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from null to a composite child', () => {
-        class Bar extends React.Component {
-          render() {
-            return null;
-          }
-        }
-
-        class Foo extends React.Component {
-          render() {
-            return this.props.children;
-          }
-        }
-
-        var elementBefore = <Foo>{null}</Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [],
-        };
-
-        var elementAfter = <Foo><Bar /></Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'Bar',
-              children: [],
-            },
-          ],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-
-      it('updates from a composite child to null', () => {
-        class Bar extends React.Component {
-          render() {
-            return null;
-          }
-        }
-
-        class Foo extends React.Component {
-          render() {
-            return this.props.children;
-          }
-        }
-
-        var elementBefore = <Foo><Bar /></Foo>;
-        var treeBefore = {
-          displayName: 'Foo',
-          children: [
-            {
-              displayName: 'Bar',
-              children: [],
-            },
-          ],
-        };
-
-        var elementAfter = <Foo>{null}</Foo>;
-        var treeAfter = {
-          displayName: 'Foo',
-          children: [],
-        };
-
-        assertTreeMatches([
-          [elementBefore, treeBefore],
-          [elementAfter, treeAfter],
-        ]);
-      });
-    });
-  });
-
-  describeStack('misc', () => {
-    it('tracks owner correctly', () => {
-      class Foo extends React.Component {
-        render() {
-          return <Bar><h1>Hi.</h1></Bar>;
-        }
-      }
-      function Bar({children}) {
-        return <div>{children} Mom</div>;
-      }
-
-      // Note that owner is not calculated for text nodes
-      // because they are not created from real elements.
-      var element = <article><Foo /></article>;
-      var tree = {
-        displayName: 'article',
-        children: [
-          {
-            displayName: 'Foo',
-            children: [
-              {
-                displayName: 'Bar',
-                ownerDisplayName: 'Foo',
-                children: [
-                  {
-                    displayName: 'div',
-                    ownerDisplayName: 'Bar',
-                    children: [
-                      {
-                        displayName: 'h1',
-                        ownerDisplayName: 'Foo',
-                        children: [
-                          {
-                            displayName: '#text',
-                            text: 'Hi.',
-                          },
-                        ],
-                      },
-                      {
-                        displayName: '#text',
-                        text: ' Mom',
-                      },
-                    ],
-                  },
-                ],
-              },
-            ],
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-
-    it('purges unmounted components automatically', () => {
-      var node = document.createElement('div');
-      var renderBar = true;
-      var fooInstance;
-      var barInstance;
-
-      class Foo extends React.Component {
-        render() {
-          fooInstance = ReactInstanceMap.get(this);
-          return renderBar ? <Bar /> : null;
-        }
-      }
-
-      class Bar extends React.Component {
-        render() {
-          barInstance = ReactInstanceMap.get(this);
-          return null;
-        }
-      }
-
-      ReactDOM.render(<Foo />, node);
-      ReactComponentTreeTestUtils.expectTree(
-        barInstance._debugID,
-        {
-          displayName: 'Bar',
-          parentDisplayName: 'Foo',
-          parentID: fooInstance._debugID,
-          children: [],
-        },
-        'Foo',
-      );
-
-      renderBar = false;
-      ReactDOM.render(<Foo />, node);
-      ReactDOM.render(<Foo />, node);
-      ReactComponentTreeTestUtils.expectTree(
-        barInstance._debugID,
-        {
-          displayName: 'Unknown',
-          children: [],
-          parentID: null,
-        },
-        'Foo',
-      );
-
-      ReactDOM.unmountComponentAtNode(node);
-      ReactComponentTreeTestUtils.expectTree(
-        barInstance._debugID,
-        {
-          displayName: 'Unknown',
-          children: [],
-          parentID: null,
-        },
-        'Foo',
-      );
-    });
-
-    it('reports update counts', () => {
-      var node = document.createElement('div');
-
-      ReactDOM.render(<div className="a" />, node);
-      var divID = ReactComponentTreeHook.getRootIDs()[0];
-      expectDev(ReactComponentTreeHook.getUpdateCount(divID)).toEqual(0);
-
-      ReactDOM.render(<span className="a" />, node);
-      var spanID = ReactComponentTreeHook.getRootIDs()[0];
-      expectDev(ReactComponentTreeHook.getUpdateCount(divID)).toEqual(0);
-      expectDev(ReactComponentTreeHook.getUpdateCount(spanID)).toEqual(0);
-
-      ReactDOM.render(<span className="b" />, node);
-      expectDev(ReactComponentTreeHook.getUpdateCount(divID)).toEqual(0);
-      expectDev(ReactComponentTreeHook.getUpdateCount(spanID)).toEqual(1);
-
-      ReactDOM.render(<span className="c" />, node);
-      expectDev(ReactComponentTreeHook.getUpdateCount(divID)).toEqual(0);
-      expectDev(ReactComponentTreeHook.getUpdateCount(spanID)).toEqual(2);
-
-      ReactDOM.unmountComponentAtNode(node);
-      expectDev(ReactComponentTreeHook.getUpdateCount(divID)).toEqual(0);
-      expectDev(ReactComponentTreeHook.getUpdateCount(spanID)).toEqual(0);
-    });
-
-    it('does not report top-level wrapper as a root', () => {
-      var node = document.createElement('div');
-
-      ReactDOM.render(<div className="a" />, node);
-      expectDev(ReactComponentTreeTestUtils.getRootDisplayNames()).toEqual([
-        'div',
-      ]);
-
-      ReactDOM.render(<div className="b" />, node);
-      expectDev(ReactComponentTreeTestUtils.getRootDisplayNames()).toEqual([
-        'div',
-      ]);
-
-      ReactDOM.unmountComponentAtNode(node);
-      expectDev(ReactComponentTreeTestUtils.getRootDisplayNames()).toEqual([]);
-      expectDev(
-        ReactComponentTreeTestUtils.getRegisteredDisplayNames(),
-      ).toEqual([]);
-    });
-
-    it('registers inlined text nodes', () => {
-      var node = document.createElement('div');
-
-      ReactDOM.render(<div>hi</div>, node);
-      expectDev(
-        ReactComponentTreeTestUtils.getRegisteredDisplayNames(),
-      ).toEqual(['div', '#text']);
-
-      ReactDOM.unmountComponentAtNode(node);
-      expectDev(
-        ReactComponentTreeTestUtils.getRegisteredDisplayNames(),
-      ).toEqual([]);
-    });
-  });
-
-  describeStack('in environment without Map, Set and Array.from', () => {
-    var realMap;
-    var realSet;
-    var realArrayFrom;
-
-    beforeEach(() => {
-      realMap = global.Map;
-      realSet = global.Set;
-      realArrayFrom = Array.from;
-
-      global.Map = undefined;
-      global.Set = undefined;
-      Array.from = undefined;
-
-      jest.resetModules();
-
-      React = require('react');
-      ReactDOM = require('react-dom');
-      ReactDOMServer = require('react-dom/server');
-      ReactInstanceMap = require('ReactInstanceMap');
-      ReactComponentTreeHook = require('ReactComponentTreeHook');
-      ReactComponentTreeTestUtils = require('ReactComponentTreeTestUtils');
-    });
-
-    afterEach(() => {
-      global.Map = realMap;
-      global.Set = realSet;
-      Array.from = realArrayFrom;
-    });
-
-    it('works', () => {
-      class Qux extends React.Component {
-        render() {
-          return null;
-        }
-      }
-
-      function Foo() {
-        return {
-          render() {
-            return <Qux />;
-          },
-        };
-      }
-      function Bar({children}) {
-        return <h1>{children}</h1>;
-      }
-      class Baz extends React.Component {
-        render() {
-          return (
-            <div>
-              <Foo />
-              <Bar>
-                <span>Hi,</span>
-                Mom
-              </Bar>
-              <a href="#">Click me.</a>
-            </div>
-          );
-        }
-      }
-
-      var element = <Baz />;
-      var tree = {
-        displayName: 'Baz',
-        element,
-        children: [
-          {
-            displayName: 'div',
-            children: [
-              {
-                displayName: 'Foo',
-                element: <Foo />,
-                children: [
-                  {
-                    displayName: 'Qux',
-                    element: <Qux />,
-                    children: [],
-                  },
-                ],
-              },
-              {
-                displayName: 'Bar',
-                children: [
-                  {
-                    displayName: 'h1',
-                    children: [
-                      {
-                        displayName: 'span',
-                        children: [
-                          {
-                            displayName: '#text',
-                            element: 'Hi,',
-                            text: 'Hi,',
-                          },
-                        ],
-                      },
-                      {
-                        displayName: '#text',
-                        text: 'Mom',
-                        element: 'Mom',
-                      },
-                    ],
-                  },
-                ],
-              },
-              {
-                displayName: 'a',
-                children: [
-                  {
-                    displayName: '#text',
-                    text: 'Click me.',
-                    element: 'Click me.',
-                  },
-                ],
-              },
-            ],
-          },
-        ],
-      };
-      assertTreeMatches([element, tree]);
-    });
-  });
-});
diff --git a/src/renderers/__tests__/ReactCompositeComponent-test.js b/src/renderers/__tests__/ReactCompositeComponent-test.js
index 650157f967f..89b44563ee2 100644
--- a/src/renderers/__tests__/ReactCompositeComponent-test.js
+++ b/src/renderers/__tests__/ReactCompositeComponent-test.js
@@ -15,7 +15,6 @@ var ChildUpdates;
 var MorphingComponent;
 var React;
 var ReactDOM;
-var ReactDOMFeatureFlags;
 var ReactDOMServer;
 var ReactCurrentOwner;
 var ReactTestUtils;
@@ -28,7 +27,6 @@ describe('ReactCompositeComponent', () => {
     jest.resetModules();
     React = require('react');
     ReactDOM = require('react-dom');
-    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
     ReactDOMServer = require('react-dom/server');
     ReactCurrentOwner = require('react')
       .__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.ReactCurrentOwner;
@@ -125,25 +123,19 @@ describe('ReactCompositeComponent', () => {
     var container = document.createElement('div');
     container.innerHTML = markup;
     ReactDOM.render(<Parent />, container);
-    if (ReactDOMFeatureFlags.useFiber) {
-      expectDev(console.warn.calls.count()).toBe(1);
-      expectDev(console.warn.calls.argsFor(0)[0]).toContain(
-        'render(): Calling ReactDOM.render() to hydrate server-rendered markup ' +
-          'will stop working in React v17. Replace the ReactDOM.render() call ' +
-          'with ReactDOM.hydrate() if you want React to attach to the server HTML.',
-      );
-    } else {
-      expectDev(console.warn.calls.count()).toBe(0);
-    }
+    expectDev(console.warn.calls.count()).toBe(1);
+    expectDev(console.warn.calls.argsFor(0)[0]).toContain(
+      'render(): Calling ReactDOM.render() to hydrate server-rendered markup ' +
+        'will stop working in React v17. Replace the ReactDOM.render() call ' +
+        'with ReactDOM.hydrate() if you want React to attach to the server HTML.',
+    );
 
     // New explicit API
     console.warn.calls.reset();
-    if (ReactDOMFeatureFlags.useFiber) {
-      container = document.createElement('div');
-      container.innerHTML = markup;
-      ReactDOM.hydrate(<Parent />, container);
-      expectDev(console.warn.calls.count()).toBe(0);
-    }
+    container = document.createElement('div');
+    container.innerHTML = markup;
+    ReactDOM.hydrate(<Parent />, container);
+    expectDev(console.warn.calls.count()).toBe(0);
   });
 
   it('should react to state changes from callbacks', () => {
diff --git a/src/renderers/__tests__/ReactCompositeComponentState-test.js b/src/renderers/__tests__/ReactCompositeComponentState-test.js
index ddfdabe106b..12d86b35fef 100644
--- a/src/renderers/__tests__/ReactCompositeComponentState-test.js
+++ b/src/renderers/__tests__/ReactCompositeComponentState-test.js
@@ -13,7 +13,6 @@
 
 var React;
 var ReactDOM;
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 
 var TestComponent;
 
@@ -181,17 +180,9 @@ describe('ReactCompositeComponent-state', () => {
       // setState({color:'green'}) only enqueues a pending state.
       ['componentWillReceiveProps-end', 'yellow'],
       // pending state queue is processed
-    ];
-
-    if (ReactDOMFeatureFlags.useFiber) {
-      // In Stack, this is never called because replaceState drops all updates
-      // from the queue. In Fiber, we keep updates in the queue to support
+      // We keep updates in the queue to support
       // replaceState(prevState => newState).
-      // TODO: Fix Stack to match Fiber.
-      expected.push(['before-setState-receiveProps', 'yellow']);
-    }
-
-    expected.push(
+      ['before-setState-receiveProps', 'yellow'],
       ['before-setState-again-receiveProps', undefined],
       ['after-setState-receiveProps', 'green'],
       ['shouldComponentUpdate-currentState', 'yellow'],
@@ -222,7 +213,7 @@ describe('ReactCompositeComponent-state', () => {
       // unmountComponent()
       // state is available within `componentWillUnmount()`
       ['componentWillUnmount', 'blue'],
-    );
+    ];
 
     expect(stateListener.mock.calls.join('\n')).toEqual(expected.join('\n'));
   });
@@ -291,20 +282,7 @@ describe('ReactCompositeComponent-state', () => {
       child.setState({bar: false});
     });
     // We expect the same thing to happen if we bail out in the middle.
-    expect(ops).toEqual(
-      ReactDOMFeatureFlags.useFiber
-        ? [
-            // Fiber works as expected
-            'child did update',
-            'parent did update',
-          ]
-        : [
-            // Stack treats these as two separate updates and therefore the order
-            // is inverse.
-            'parent did update',
-            'child did update',
-          ],
-    );
+    expect(ops).toEqual(['child did update', 'parent did update']);
   });
 
   it('should batch unmounts', () => {
@@ -447,45 +425,43 @@ describe('ReactCompositeComponent-state', () => {
     );
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    it('should treat assigning to this.state inside cWM as a replaceState, with a warning', () => {
-      spyOn(console, 'error');
-
-      let ops = [];
-      class Test extends React.Component {
-        state = {step: 1, extra: true};
-        componentWillMount() {
-          this.setState({step: 2}, () => {
-            // Tests that earlier setState callbacks are not dropped
-            ops.push(
-              `callback -- step: ${this.state.step}, extra: ${!!this.state.extra}`,
-            );
-          });
-          // Treat like replaceState
-          this.state = {step: 3};
-        }
-        render() {
+  it('should treat assigning to this.state inside cWM as a replaceState, with a warning', () => {
+    spyOn(console, 'error');
+
+    let ops = [];
+    class Test extends React.Component {
+      state = {step: 1, extra: true};
+      componentWillMount() {
+        this.setState({step: 2}, () => {
+          // Tests that earlier setState callbacks are not dropped
           ops.push(
-            `render -- step: ${this.state.step}, extra: ${!!this.state.extra}`,
+            `callback -- step: ${this.state.step}, extra: ${!!this.state.extra}`,
           );
-          return null;
-        }
+        });
+        // Treat like replaceState
+        this.state = {step: 3};
       }
+      render() {
+        ops.push(
+          `render -- step: ${this.state.step}, extra: ${!!this.state.extra}`,
+        );
+        return null;
+      }
+    }
 
-      // Mount
-      const container = document.createElement('div');
-      ReactDOM.render(<Test />, container);
-
-      expect(ops).toEqual([
-        'render -- step: 3, extra: false',
-        'callback -- step: 3, extra: false',
-      ]);
-      expect(console.error.calls.count()).toEqual(1);
-      expect(console.error.calls.argsFor(0)[0]).toEqual(
-        'Warning: Test.componentWillMount(): Assigning directly to ' +
-          "this.state is deprecated (except inside a component's constructor). " +
-          'Use setState instead.',
-      );
-    });
-  }
+    // Mount
+    const container = document.createElement('div');
+    ReactDOM.render(<Test />, container);
+
+    expect(ops).toEqual([
+      'render -- step: 3, extra: false',
+      'callback -- step: 3, extra: false',
+    ]);
+    expect(console.error.calls.count()).toEqual(1);
+    expect(console.error.calls.argsFor(0)[0]).toEqual(
+      'Warning: Test.componentWillMount(): Assigning directly to ' +
+        "this.state is deprecated (except inside a component's constructor). " +
+        'Use setState instead.',
+    );
+  });
 });
diff --git a/src/renderers/__tests__/ReactEmptyComponent-test.js b/src/renderers/__tests__/ReactEmptyComponent-test.js
index 5368ae06a90..f3b08b22c07 100644
--- a/src/renderers/__tests__/ReactEmptyComponent-test.js
+++ b/src/renderers/__tests__/ReactEmptyComponent-test.js
@@ -13,7 +13,6 @@
 
 var React;
 var ReactDOM;
-var ReactDOMFeatureFlags;
 var ReactTestUtils;
 var TogglingComponent;
 
@@ -25,7 +24,6 @@ describe('ReactEmptyComponent', () => {
 
     React = require('react');
     ReactDOM = require('react-dom');
-    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
     ReactTestUtils = require('react-dom/test-utils');
 
     log = jasmine.createSpy();
@@ -237,15 +235,8 @@ describe('ReactEmptyComponent', () => {
     var div = document.createElement('div');
 
     try {
-      if (ReactDOMFeatureFlags.useFiber) {
-        ReactDOM.render(null, div);
-        expect(div.innerHTML).toBe('');
-      } else {
-        // Stack does not implement this.
-        expect(function() {
-          ReactDOM.render(null, div);
-        }).toThrowError('ReactDOM.render(): Invalid component element.');
-      }
+      ReactDOM.render(null, div);
+      expect(div.innerHTML).toBe('');
     } finally {
       ReactFeatureFlags.disableNewFiberFeatures = true;
     }
@@ -300,21 +291,11 @@ describe('ReactEmptyComponent', () => {
 
     ReactDOM.render(<Empty />, container);
     var noscript1 = container.firstChild;
-    if (ReactDOMFeatureFlags.useFiber) {
-      expect(noscript1).toBe(null);
-    } else {
-      expect(noscript1.nodeName).toBe('#comment');
-    }
+    expect(noscript1).toBe(null);
 
     // This update shouldn't create a DOM node
     ReactDOM.render(<Empty />, container);
     var noscript2 = container.firstChild;
-    if (ReactDOMFeatureFlags.useFiber) {
-      expect(noscript1).toBe(null);
-    } else {
-      expect(noscript2.nodeName).toBe('#comment');
-    }
-
-    expect(noscript1).toBe(noscript2);
+    expect(noscript2).toBe(null);
   });
 });
diff --git a/src/renderers/__tests__/ReactErrorBoundaries-test.js b/src/renderers/__tests__/ReactErrorBoundaries-test.js
index ea994b41922..7be72fb2818 100644
--- a/src/renderers/__tests__/ReactErrorBoundaries-test.js
+++ b/src/renderers/__tests__/ReactErrorBoundaries-test.js
@@ -11,8 +11,6 @@
 
 'use strict';
 
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-
 var PropTypes;
 var React;
 var ReactDOM;
@@ -401,12 +399,7 @@ describe('ReactErrorBoundaries', () => {
         log.push('NoopErrorBoundary componentWillUnmount');
       }
       componentDidCatch() {
-        if (ReactDOMFeatureFlags.useFiber) {
-          log.push('NoopErrorBoundary componentDidCatch');
-        } else {
-          // In Stack, not calling setState() is treated as a rethrow.
-          log.push('NoopErrorBoundary componentDidCatch [*]');
-        }
+        log.push('NoopErrorBoundary componentDidCatch');
       }
     };
 
@@ -509,14 +502,9 @@ describe('ReactErrorBoundaries', () => {
         log.push('RetryErrorBoundary componentWillUnmount');
       }
       componentDidCatch(error) {
-        if (ReactDOMFeatureFlags.useFiber) {
-          log.push('RetryErrorBoundary componentDidCatch [!]');
-          // In Fiber, calling setState() (and failing) is treated as a rethrow.
-          this.setState({});
-        } else {
-          log.push('RetryErrorBoundary componentDidCatch [*]');
-          // In Stack, not calling setState() is treated as a rethrow.
-        }
+        log.push('RetryErrorBoundary componentDidCatch [!]');
+        // In Fiber, calling setState() (and failing) is treated as a rethrow.
+        this.setState({});
       }
     };
 
@@ -641,22 +629,13 @@ describe('ReactErrorBoundaries', () => {
       'BrokenRender constructor',
       'BrokenRender componentWillMount',
       'BrokenRender render [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Fiber mounts with null children before capturing error
-            'ErrorBoundary componentDidMount',
-            // Catch and render an error message
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            // Catch and render an error message
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidMount',
-          ]),
+      // Fiber mounts with null children before capturing error
+      'ErrorBoundary componentDidMount',
+      // Catch and render an error message
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -678,22 +657,13 @@ describe('ReactErrorBoundaries', () => {
       'ErrorBoundary componentWillMount',
       'ErrorBoundary render success',
       'BrokenConstructor constructor [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Fiber mounts with null children before capturing error
-            'ErrorBoundary componentDidMount',
-            // Catch and render an error message
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            // Catch and render an error message
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidMount',
-          ]),
+      // Fiber mounts with null children before capturing error
+      'ErrorBoundary componentDidMount',
+      // Catch and render an error message
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -716,20 +686,11 @@ describe('ReactErrorBoundaries', () => {
       'ErrorBoundary render success',
       'BrokenComponentWillMount constructor',
       'BrokenComponentWillMount componentWillMount [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            'ErrorBoundary componentDidMount',
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            // Catch and render an error message
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidMount',
-          ]),
+      'ErrorBoundary componentDidMount',
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -808,29 +769,15 @@ describe('ReactErrorBoundaries', () => {
       'BrokenRender constructor',
       'BrokenRender componentWillMount',
       'BrokenRender render [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            'ErrorBoundary componentDidMount',
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorMessage constructor',
-            'ErrorMessage componentWillMount',
-            'ErrorMessage render',
-            'ErrorMessage componentDidMount',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            // Handle the error:
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary render error',
-            // Mount the error message:
-            'ErrorMessage constructor',
-            'ErrorMessage componentWillMount',
-            'ErrorMessage render',
-            'ErrorMessage componentDidMount',
-            'ErrorBoundary componentDidMount',
-          ]),
+      'ErrorBoundary componentDidMount',
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorMessage constructor',
+      'ErrorMessage componentWillMount',
+      'ErrorMessage render',
+      'ErrorMessage componentDidMount',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -862,39 +809,22 @@ describe('ReactErrorBoundaries', () => {
       'BrokenRender constructor',
       'BrokenRender componentWillMount',
       'BrokenRender render [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // In Fiber, failed error boundaries render null before attempting to recover
-            'RetryErrorBoundary componentDidMount',
-            'RetryErrorBoundary componentDidCatch [!]',
-            'ErrorBoundary componentDidMount',
-            // Retry
-            'RetryErrorBoundary render',
-            'BrokenRender constructor',
-            'BrokenRender componentWillMount',
-            'BrokenRender render [!]',
-            // This time, the error propagates to the higher boundary
-            'RetryErrorBoundary componentWillUnmount',
-            'ErrorBoundary componentDidCatch',
-            // Render the error
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            // The first error boundary catches the error.
-            // However, it doesn't adjust its state so next render will also fail.
-            'RetryErrorBoundary componentDidCatch [*]',
-            'RetryErrorBoundary render',
-            'BrokenRender constructor',
-            'BrokenRender componentWillMount',
-            'BrokenRender render [!]',
-            // This time, the error propagates to the higher boundary
-            'ErrorBoundary componentDidCatch',
-            // Render the error
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidMount',
-          ]),
+      // In Fiber, failed error boundaries render null before attempting to recover
+      'RetryErrorBoundary componentDidMount',
+      'RetryErrorBoundary componentDidCatch [!]',
+      'ErrorBoundary componentDidMount',
+      // Retry
+      'RetryErrorBoundary render',
+      'BrokenRender constructor',
+      'BrokenRender componentWillMount',
+      'BrokenRender render [!]',
+      // This time, the error propagates to the higher boundary
+      'RetryErrorBoundary componentWillUnmount',
+      'ErrorBoundary componentDidCatch',
+      // Render the error
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -918,20 +848,11 @@ describe('ReactErrorBoundaries', () => {
       'BrokenComponentWillMountErrorBoundary constructor',
       'BrokenComponentWillMountErrorBoundary componentWillMount [!]',
       // The error propagates to the higher boundary
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            'ErrorBoundary componentDidMount',
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            'ErrorBoundary componentDidCatch',
-            // Render the error
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidMount',
-          ]),
+      'ErrorBoundary componentDidMount',
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -962,31 +883,19 @@ describe('ReactErrorBoundaries', () => {
       'BrokenRender render [!]',
       // The first error boundary catches the error
       // It adjusts state but throws displaying the message
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Finish mounting with null children
-            'BrokenRenderErrorBoundary componentDidMount',
-            // Attempt to handle the error
-            'BrokenRenderErrorBoundary componentDidCatch',
-            'ErrorBoundary componentDidMount',
-            'BrokenRenderErrorBoundary render error [!]',
-            // Boundary fails with new error, propagate to next boundary
-            'BrokenRenderErrorBoundary componentWillUnmount',
-            // Attempt to handle the error again
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            'BrokenRenderErrorBoundary componentDidCatch',
-            'BrokenRenderErrorBoundary render error [!]',
-            // The error propagates to the higher boundary
-            'ErrorBoundary componentDidCatch',
-            // Render the error
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidMount',
-          ]),
+      // Finish mounting with null children
+      'BrokenRenderErrorBoundary componentDidMount',
+      // Attempt to handle the error
+      'BrokenRenderErrorBoundary componentDidCatch',
+      'ErrorBoundary componentDidMount',
+      'BrokenRenderErrorBoundary render error [!]',
+      // Boundary fails with new error, propagate to next boundary
+      'BrokenRenderErrorBoundary componentWillUnmount',
+      // Attempt to handle the error again
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1017,23 +926,14 @@ describe('ReactErrorBoundaries', () => {
       'BrokenRender constructor',
       'BrokenRender componentWillMount',
       'BrokenRender render [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Finish mounting with null children
-            'ErrorBoundary componentDidMount',
-            // Handle the error
-            'ErrorBoundary componentDidCatch',
-            // Render the error message
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            'ErrorBoundary componentDidCatch',
-            // Render the error message
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidMount',
-          ]),
+      // Finish mounting with null children
+      'ErrorBoundary componentDidMount',
+      // Handle the error
+      'ErrorBoundary componentDidCatch',
+      // Render the error message
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1066,28 +966,15 @@ describe('ReactErrorBoundaries', () => {
       'BrokenRender componentWillMount',
       'BrokenRender render [!]',
       // Handle error:
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Finish mounting with null children
-            'ErrorBoundary componentDidMount',
-            // Handle the error
-            'ErrorBoundary componentDidCatch',
-            // Render the error message
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'Error message ref is set to [object HTMLDivElement]',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            'ErrorBoundary componentDidCatch',
-            // Stack reconciler resets ref on update, as it doesn't know ref was never set.
-            // This is unnecessary, and Fiber doesn't do it:
-            'Child ref is set to null',
-            'ErrorBoundary render error',
-            // Ref to error message should get set:
-            'Error message ref is set to [object HTMLDivElement]',
-            'ErrorBoundary componentDidMount',
-          ]),
+      // Finish mounting with null children
+      'ErrorBoundary componentDidMount',
+      // Handle the error
+      'ErrorBoundary componentDidCatch',
+      // Render the error message
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'Error message ref is set to [object HTMLDivElement]',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1151,26 +1038,15 @@ describe('ReactErrorBoundaries', () => {
       'Normal2 render',
       // BrokenConstructor will abort rendering:
       'BrokenConstructor constructor [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Finish updating with null children
-            'Normal componentWillUnmount',
-            'ErrorBoundary componentDidUpdate',
-            // Handle the error
-            'ErrorBoundary componentDidCatch',
-            // Render the error message
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            'ErrorBoundary componentDidCatch',
-            // Stack unmounts first, then renders:
-            'Normal componentWillUnmount',
-            'ErrorBoundary render error',
-            // Normal2 does not get lifefycle because it was never mounted
-            'ErrorBoundary componentDidUpdate',
-          ]),
+      // Finish updating with null children
+      'Normal componentWillUnmount',
+      'ErrorBoundary componentDidUpdate',
+      // Handle the error
+      'ErrorBoundary componentDidCatch',
+      // Render the error message
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1211,26 +1087,15 @@ describe('ReactErrorBoundaries', () => {
       // BrokenComponentWillMount will abort rendering:
       'BrokenComponentWillMount constructor',
       'BrokenComponentWillMount componentWillMount [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Finish updating with null children
-            'Normal componentWillUnmount',
-            'ErrorBoundary componentDidUpdate',
-            // Handle the error
-            'ErrorBoundary componentDidCatch',
-            // Render the error message
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            'ErrorBoundary componentDidCatch',
-            // Stack unmounts first, then renders:
-            'Normal componentWillUnmount',
-            'ErrorBoundary render error',
-            // Normal2 does not get lifefycle because it was never mounted
-            'ErrorBoundary componentDidUpdate',
-          ]),
+      // Finish updating with null children
+      'Normal componentWillUnmount',
+      'ErrorBoundary componentDidUpdate',
+      // Handle the error
+      'ErrorBoundary componentDidCatch',
+      // Render the error message
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1266,26 +1131,15 @@ describe('ReactErrorBoundaries', () => {
       'Normal render',
       // BrokenComponentWillReceiveProps will abort rendering:
       'BrokenComponentWillReceiveProps componentWillReceiveProps [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Finish updating with null children
-            'Normal componentWillUnmount',
-            'BrokenComponentWillReceiveProps componentWillUnmount',
-            'ErrorBoundary componentDidUpdate',
-            // Handle the error
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            'ErrorBoundary componentDidCatch',
-            // Stack unmounts first, then renders:
-            'Normal componentWillUnmount',
-            'BrokenComponentWillReceiveProps componentWillUnmount',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]),
+      // Finish updating with null children
+      'Normal componentWillUnmount',
+      'BrokenComponentWillReceiveProps componentWillUnmount',
+      'ErrorBoundary componentDidUpdate',
+      // Handle the error
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1322,26 +1176,15 @@ describe('ReactErrorBoundaries', () => {
       // BrokenComponentWillUpdate will abort rendering:
       'BrokenComponentWillUpdate componentWillReceiveProps',
       'BrokenComponentWillUpdate componentWillUpdate [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Finish updating with null children
-            'Normal componentWillUnmount',
-            'BrokenComponentWillUpdate componentWillUnmount',
-            'ErrorBoundary componentDidUpdate',
-            // Handle the error
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            'ErrorBoundary componentDidCatch',
-            // Stack unmounts first, then renders:
-            'Normal componentWillUnmount',
-            'BrokenComponentWillUpdate componentWillUnmount',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]),
+      // Finish updating with null children
+      'Normal componentWillUnmount',
+      'BrokenComponentWillUpdate componentWillUnmount',
+      'ErrorBoundary componentDidUpdate',
+      // Handle the error
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1383,25 +1226,14 @@ describe('ReactErrorBoundaries', () => {
       'BrokenRender constructor',
       'BrokenRender componentWillMount',
       'BrokenRender render [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Finish updating with null children
-            'Normal componentWillUnmount',
-            'ErrorBoundary componentDidUpdate',
-            // Handle the error
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            'ErrorBoundary componentDidCatch',
-            // Stack unmounts first, then renders:
-            'Normal componentWillUnmount',
-            'ErrorBoundary render error',
-            // Normal2 does not get lifefycle because it was never mounted
-            'ErrorBoundary componentDidUpdate',
-          ]),
+      // Finish updating with null children
+      'Normal componentWillUnmount',
+      'ErrorBoundary componentDidUpdate',
+      // Handle the error
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1453,22 +1285,13 @@ describe('ReactErrorBoundaries', () => {
       'BrokenRender constructor',
       'BrokenRender componentWillMount',
       'BrokenRender render [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Finish updating with null children
-            'Child1 ref is set to null',
-            'ErrorBoundary componentDidUpdate',
-            // Handle the error
-            'ErrorBoundary componentDidCatch',
-            'ErrorBoundary componentWillUpdate',
-            'ErrorBoundary render error',
-          ]
-        : [
-            'ErrorBoundary componentDidCatch',
-            // Stack resets ref first, renders later
-            'Child1 ref is set to null',
-            'ErrorBoundary render error',
-          ]),
+      // Finish updating with null children
+      'Child1 ref is set to null',
+      'ErrorBoundary componentDidUpdate',
+      // Handle the error
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
       'Error message ref is set to [object HTMLDivElement]',
       // Child2 ref is never set because its mounting aborted
       'ErrorBoundary componentDidUpdate',
@@ -1511,35 +1334,22 @@ describe('ReactErrorBoundaries', () => {
       'BrokenComponentWillUnmount render',
       // Unmounting throws:
       'BrokenComponentWillUnmount componentWillUnmount [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Fiber proceeds with lifecycles despite errors
-            'Normal componentWillUnmount',
-            // The components have updated in this phase
-            'BrokenComponentWillUnmount componentDidUpdate',
-            'ErrorBoundary componentDidUpdate',
-            // Now that commit phase is done, Fiber unmounts the boundary's children
-            'BrokenComponentWillUnmount componentWillUnmount [!]',
-            'ErrorBoundary componentDidCatch',
-            // The initial render was aborted, so
-            // Fiber retries from the root.
-            'ErrorBoundary componentWillUpdate',
-            // Render an error now (stack will do it later)
-            'ErrorBoundary render error',
-            // Attempt to unmount previous child:
-            // Done
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            // Stack will handle error immediately
-            'ErrorBoundary componentDidCatch',
-            // Attempt to unmount previous children:
-            'BrokenComponentWillUnmount componentWillUnmount [!]',
-            'Normal componentWillUnmount',
-            // Render an error now (Fiber will do it earlier)
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]),
+      // Fiber proceeds with lifecycles despite errors
+      'Normal componentWillUnmount',
+      // The components have updated in this phase
+      'BrokenComponentWillUnmount componentDidUpdate',
+      'ErrorBoundary componentDidUpdate',
+      // Now that commit phase is done, Fiber unmounts the boundary's children
+      'BrokenComponentWillUnmount componentWillUnmount [!]',
+      'ErrorBoundary componentDidCatch',
+      // The initial render was aborted, so
+      // Fiber retries from the root.
+      'ErrorBoundary componentWillUpdate',
+      // Render an error now (stack will do it later)
+      'ErrorBoundary render error',
+      // Attempt to unmount previous child:
+      // Done
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1582,33 +1392,21 @@ describe('ReactErrorBoundaries', () => {
       'BrokenComponentWillUnmount render',
       // Unmounting throws:
       'BrokenComponentWillUnmount componentWillUnmount [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Fiber proceeds with lifecycles despite errors
-            'BrokenComponentWillUnmount componentDidUpdate',
-            'Normal componentDidUpdate',
-            'ErrorBoundary componentDidUpdate',
-            'Normal componentWillUnmount',
-            'BrokenComponentWillUnmount componentWillUnmount [!]',
-            // Now that commit phase is done, Fiber handles errors
-            'ErrorBoundary componentDidCatch',
-            // The initial render was aborted, so
-            // Fiber retries from the root.
-            'ErrorBoundary componentWillUpdate',
-            // Render an error now (stack will do it later)
-            'ErrorBoundary render error',
-            // Done
-            'ErrorBoundary componentDidUpdate',
-          ]
-        : [
-            'ErrorBoundary componentDidCatch',
-            // Attempt to unmount previous children:
-            'Normal componentWillUnmount',
-            'BrokenComponentWillUnmount componentWillUnmount [!]',
-            // Stack calls lifecycles first, then renders.
-            'ErrorBoundary render error',
-            'ErrorBoundary componentDidUpdate',
-          ]),
+      // Fiber proceeds with lifecycles despite errors
+      'BrokenComponentWillUnmount componentDidUpdate',
+      'Normal componentDidUpdate',
+      'ErrorBoundary componentDidUpdate',
+      'Normal componentWillUnmount',
+      'BrokenComponentWillUnmount componentWillUnmount [!]',
+      // Now that commit phase is done, Fiber handles errors
+      'ErrorBoundary componentDidCatch',
+      // The initial render was aborted, so
+      // Fiber retries from the root.
+      'ErrorBoundary componentWillUpdate',
+      // Render an error now (stack will do it later)
+      'ErrorBoundary render error',
+      // Done
+      'ErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1662,31 +1460,19 @@ describe('ReactErrorBoundaries', () => {
       'InnerErrorBoundary render success',
       // Try unmounting child
       'BrokenComponentWillUnmount componentWillUnmount [!]',
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            // Fiber proceeds with lifecycles despite errors
-            // Inner and outer boundaries have updated in this phase
-            'InnerErrorBoundary componentDidUpdate',
-            'OuterErrorBoundary componentDidUpdate',
-            // Now that commit phase is done, Fiber handles errors
-            // Only inner boundary receives the error:
-            'InnerErrorBoundary componentDidCatch',
-            'InnerErrorBoundary componentWillUpdate',
-            // Render an error now
-            'InnerErrorBoundary render error',
-            // In Fiber, this was a local update to the
-            // inner boundary so only its hook fires
-            'InnerErrorBoundary componentDidUpdate',
-          ]
-        : [
-            // Stack will handle error immediately
-            'InnerErrorBoundary componentDidCatch',
-            'InnerErrorBoundary render error',
-            // In stack, this was a part of the update to the
-            // outer boundary so both lifecycles fire
-            'InnerErrorBoundary componentDidUpdate',
-            'OuterErrorBoundary componentDidUpdate',
-          ]),
+      // Fiber proceeds with lifecycles despite errors
+      // Inner and outer boundaries have updated in this phase
+      'InnerErrorBoundary componentDidUpdate',
+      'OuterErrorBoundary componentDidUpdate',
+      // Now that commit phase is done, Fiber handles errors
+      // Only inner boundary receives the error:
+      'InnerErrorBoundary componentDidCatch',
+      'InnerErrorBoundary componentWillUpdate',
+      // Render an error now
+      'InnerErrorBoundary render error',
+      // In Fiber, this was a local update to the
+      // inner boundary so only its hook fires
+      'InnerErrorBoundary componentDidUpdate',
     ]);
 
     log.length = 0;
@@ -1858,374 +1644,371 @@ describe('ReactErrorBoundaries', () => {
     expect(log).toEqual(['ErrorBoundary componentWillUnmount']);
   });
 
-  // The tests below implement new features in Fiber.
-  if (ReactDOMFeatureFlags.useFiber) {
-    it('catches errors originating downstream', () => {
-      var fail = false;
-      class Stateful extends React.Component {
-        state = {shouldThrow: false};
+  it('catches errors originating downstream', () => {
+    var fail = false;
+    class Stateful extends React.Component {
+      state = {shouldThrow: false};
 
-        render() {
-          if (fail) {
-            log.push('Stateful render [!]');
-            throw new Error('Hello');
-          }
-          return <div>{this.props.children}</div>;
+      render() {
+        if (fail) {
+          log.push('Stateful render [!]');
+          throw new Error('Hello');
         }
+        return <div>{this.props.children}</div>;
       }
+    }
 
-      var statefulInst;
-      var container = document.createElement('div');
-      ReactDOM.render(
-        <ErrorBoundary>
-          <Stateful ref={inst => (statefulInst = inst)} />
-        </ErrorBoundary>,
-        container,
-      );
-
-      log.length = 0;
-      expect(() => {
-        fail = true;
-        statefulInst.forceUpdate();
-      }).not.toThrow();
-
-      expect(log).toEqual([
-        'Stateful render [!]',
-        'ErrorBoundary componentDidCatch',
-        'ErrorBoundary componentWillUpdate',
-        'ErrorBoundary render error',
-        'ErrorBoundary componentDidUpdate',
-      ]);
-
-      log.length = 0;
-      ReactDOM.unmountComponentAtNode(container);
-      expect(log).toEqual(['ErrorBoundary componentWillUnmount']);
-    });
-
-    it('catches errors in componentDidMount', () => {
-      var container = document.createElement('div');
-      ReactDOM.render(
-        <ErrorBoundary>
-          <BrokenComponentWillUnmount>
-            <Normal />
-          </BrokenComponentWillUnmount>
-          <BrokenComponentDidMount />
-          <Normal logName="LastChild" />
-        </ErrorBoundary>,
-        container,
-      );
-      expect(log).toEqual([
-        'ErrorBoundary constructor',
-        'ErrorBoundary componentWillMount',
-        'ErrorBoundary render success',
-        'BrokenComponentWillUnmount constructor',
-        'BrokenComponentWillUnmount componentWillMount',
-        'BrokenComponentWillUnmount render',
-        'Normal constructor',
-        'Normal componentWillMount',
-        'Normal render',
-        'BrokenComponentDidMount constructor',
-        'BrokenComponentDidMount componentWillMount',
-        'BrokenComponentDidMount render',
-        'LastChild constructor',
-        'LastChild componentWillMount',
-        'LastChild render',
-        // Start flushing didMount queue
-        'Normal componentDidMount',
-        'BrokenComponentWillUnmount componentDidMount',
-        'BrokenComponentDidMount componentDidMount [!]',
-        // Continue despite the error
-        'LastChild componentDidMount',
-        'ErrorBoundary componentDidMount',
-        // Now we are ready to handle the error
-        // Safely unmount every child
-        'BrokenComponentWillUnmount componentWillUnmount [!]',
-        // Continue unmounting safely despite any errors
-        'Normal componentWillUnmount',
-        'BrokenComponentDidMount componentWillUnmount',
-        'LastChild componentWillUnmount',
-        // Handle the error
-        'ErrorBoundary componentDidCatch',
-        'ErrorBoundary componentWillUpdate',
-        'ErrorBoundary render error',
-        // The update has finished
-        'ErrorBoundary componentDidUpdate',
-      ]);
-
-      log.length = 0;
-      ReactDOM.unmountComponentAtNode(container);
-      expect(log).toEqual(['ErrorBoundary componentWillUnmount']);
-    });
-
-    it('catches errors in componentDidUpdate', () => {
-      var container = document.createElement('div');
-      ReactDOM.render(
-        <ErrorBoundary>
-          <BrokenComponentDidUpdate />
-        </ErrorBoundary>,
-        container,
-      );
-
-      log.length = 0;
-      ReactDOM.render(
-        <ErrorBoundary>
-          <BrokenComponentDidUpdate />
-        </ErrorBoundary>,
-        container,
-      );
-      expect(log).toEqual([
-        'ErrorBoundary componentWillReceiveProps',
-        'ErrorBoundary componentWillUpdate',
-        'ErrorBoundary render success',
-        'BrokenComponentDidUpdate componentWillReceiveProps',
-        'BrokenComponentDidUpdate componentWillUpdate',
-        'BrokenComponentDidUpdate render',
-        // All lifecycles run
-        'BrokenComponentDidUpdate componentDidUpdate [!]',
-        'ErrorBoundary componentDidUpdate',
-        'BrokenComponentDidUpdate componentWillUnmount',
-        // Then, error is handled
-        'ErrorBoundary componentDidCatch',
-        'ErrorBoundary componentWillUpdate',
-        'ErrorBoundary render error',
-        'ErrorBoundary componentDidUpdate',
-      ]);
-
-      log.length = 0;
-      ReactDOM.unmountComponentAtNode(container);
-      expect(log).toEqual(['ErrorBoundary componentWillUnmount']);
-    });
-
-    it('propagates errors inside boundary during componentDidMount', () => {
-      var container = document.createElement('div');
-      ReactDOM.render(
-        <ErrorBoundary>
-          <BrokenComponentDidMountErrorBoundary
-            renderError={error => (
-              <div>
-                We should never catch our own error: {error.message}.
-              </div>
-            )}
-          />
-        </ErrorBoundary>,
-        container,
-      );
-      expect(container.firstChild.textContent).toBe('Caught an error: Hello.');
-      expect(log).toEqual([
-        'ErrorBoundary constructor',
-        'ErrorBoundary componentWillMount',
-        'ErrorBoundary render success',
-        'BrokenComponentDidMountErrorBoundary constructor',
-        'BrokenComponentDidMountErrorBoundary componentWillMount',
-        'BrokenComponentDidMountErrorBoundary render success',
-        'BrokenComponentDidMountErrorBoundary componentDidMount [!]',
-        // Fiber proceeds with the hooks
-        'ErrorBoundary componentDidMount',
-        'BrokenComponentDidMountErrorBoundary componentWillUnmount',
-        // The error propagates to the higher boundary
-        'ErrorBoundary componentDidCatch',
-        // Fiber retries from the root
-        'ErrorBoundary componentWillUpdate',
-        'ErrorBoundary render error',
-        'ErrorBoundary componentDidUpdate',
-      ]);
-
-      log.length = 0;
-      ReactDOM.unmountComponentAtNode(container);
-      expect(log).toEqual(['ErrorBoundary componentWillUnmount']);
-    });
-
-    it('lets different boundaries catch their own first errors', () => {
-      function renderUnmountError(error) {
-        return <div>Caught an unmounting error: {error.message}.</div>;
-      }
-      function renderUpdateError(error) {
-        return <div>Caught an updating error: {error.message}.</div>;
-      }
-
-      var container = document.createElement('div');
-      ReactDOM.render(
-        <ErrorBoundary logName="OuterErrorBoundary">
-          <ErrorBoundary
-            logName="InnerUnmountBoundary"
-            renderError={renderUnmountError}>
-            <BrokenComponentWillUnmount errorText="E1" />
-            <BrokenComponentWillUnmount errorText="E2" />
-          </ErrorBoundary>
-          <ErrorBoundary
-            logName="InnerUpdateBoundary"
-            renderError={renderUpdateError}>
-            <BrokenComponentDidUpdate errorText="E3" />
-            <BrokenComponentDidUpdate errorText="E4" />
-          </ErrorBoundary>
-        </ErrorBoundary>,
-        container,
-      );
-
-      log.length = 0;
-      ReactDOM.render(
-        <ErrorBoundary logName="OuterErrorBoundary">
-          <ErrorBoundary
-            logName="InnerUnmountBoundary"
-            renderError={renderUnmountError}
-          />
-          <ErrorBoundary
-            logName="InnerUpdateBoundary"
-            renderError={renderUpdateError}>
-            <BrokenComponentDidUpdate errorText="E3" />
-            <BrokenComponentDidUpdate errorText="E4" />
-          </ErrorBoundary>
-        </ErrorBoundary>,
-        container,
-      );
-
-      expect(container.firstChild.textContent).toBe(
-        'Caught an unmounting error: E1.' + 'Caught an updating error: E3.',
-      );
-      expect(log).toEqual([
-        // Begin update phase
-        'OuterErrorBoundary componentWillReceiveProps',
-        'OuterErrorBoundary componentWillUpdate',
-        'OuterErrorBoundary render success',
-        'InnerUnmountBoundary componentWillReceiveProps',
-        'InnerUnmountBoundary componentWillUpdate',
-        'InnerUnmountBoundary render success',
-        'InnerUpdateBoundary componentWillReceiveProps',
-        'InnerUpdateBoundary componentWillUpdate',
-        'InnerUpdateBoundary render success',
-        // First come the updates
-        'BrokenComponentDidUpdate componentWillReceiveProps',
-        'BrokenComponentDidUpdate componentWillUpdate',
-        'BrokenComponentDidUpdate render',
-        'BrokenComponentDidUpdate componentWillReceiveProps',
-        'BrokenComponentDidUpdate componentWillUpdate',
-        'BrokenComponentDidUpdate render',
-        // We're in commit phase now, deleting
-        'BrokenComponentWillUnmount componentWillUnmount [!]',
-        'BrokenComponentWillUnmount componentWillUnmount [!]',
-        // Continue despite errors, handle them after commit is done
-        'InnerUnmountBoundary componentDidUpdate',
-        // We're still in commit phase, now calling update lifecycles
-        'BrokenComponentDidUpdate componentDidUpdate [!]',
-        // Again, continue despite errors, we'll handle them later
-        'BrokenComponentDidUpdate componentDidUpdate [!]',
-        'InnerUpdateBoundary componentDidUpdate',
-        'OuterErrorBoundary componentDidUpdate',
-        // After the commit phase, attempt to recover from any errors that
-        // were captured
-        'BrokenComponentDidUpdate componentWillUnmount',
-        'BrokenComponentDidUpdate componentWillUnmount',
-        'InnerUnmountBoundary componentDidCatch',
-        'InnerUpdateBoundary componentDidCatch',
-        'InnerUnmountBoundary componentWillUpdate',
-        'InnerUnmountBoundary render error',
-        'InnerUpdateBoundary componentWillUpdate',
-        'InnerUpdateBoundary render error',
-        'InnerUnmountBoundary componentDidUpdate',
-        'InnerUpdateBoundary componentDidUpdate',
-      ]);
-
-      log.length = 0;
-      ReactDOM.unmountComponentAtNode(container);
-      expect(log).toEqual([
-        'OuterErrorBoundary componentWillUnmount',
-        'InnerUnmountBoundary componentWillUnmount',
-        'InnerUpdateBoundary componentWillUnmount',
-      ]);
-    });
-
-    it('discards a bad root if the root component fails', () => {
-      spyOn(console, 'error');
-
-      const X = null;
-      const Y = undefined;
-      let err1;
-      let err2;
-
-      try {
-        let container = document.createElement('div');
-        ReactDOM.render(<X />, container);
-      } catch (err) {
-        err1 = err;
-      }
-      try {
-        let container = document.createElement('div');
-        ReactDOM.render(<Y />, container);
-      } catch (err) {
-        err2 = err;
-      }
-
-      expect(err1.message).toMatch(/got: null/);
-      expect(err2.message).toMatch(/got: undefined/);
-    });
-
-    it('renders empty output if error boundary does not handle the error', () => {
-      var container = document.createElement('div');
-      ReactDOM.render(
-        <div>
-          Sibling
-          <NoopErrorBoundary>
-            <BrokenRender />
-          </NoopErrorBoundary>
-        </div>,
-        container,
-      );
-      expect(container.firstChild.textContent).toBe('Sibling');
-      expect(log).toEqual([
-        'NoopErrorBoundary constructor',
-        'NoopErrorBoundary componentWillMount',
-        'NoopErrorBoundary render',
-        'BrokenRender constructor',
-        'BrokenRender componentWillMount',
-        'BrokenRender render [!]',
-        // In Fiber, noop error boundaries render null
-        'NoopErrorBoundary componentDidMount',
-        'NoopErrorBoundary componentDidCatch',
-        // Nothing happens.
-      ]);
-
-      log.length = 0;
-      ReactDOM.unmountComponentAtNode(container);
-      expect(log).toEqual(['NoopErrorBoundary componentWillUnmount']);
-    });
+    var statefulInst;
+    var container = document.createElement('div');
+    ReactDOM.render(
+      <ErrorBoundary>
+        <Stateful ref={inst => (statefulInst = inst)} />
+      </ErrorBoundary>,
+      container,
+    );
 
-    it('passes first error when two errors happen in commit', () => {
-      const errors = [];
-      let caughtError;
-      class Parent extends React.Component {
-        render() {
-          return <Child />;
-        }
-        componentDidMount() {
-          errors.push('parent sad');
-          throw new Error('parent sad');
-        }
+    log.length = 0;
+    expect(() => {
+      fail = true;
+      statefulInst.forceUpdate();
+    }).not.toThrow();
+
+    expect(log).toEqual([
+      'Stateful render [!]',
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
+    ]);
+
+    log.length = 0;
+    ReactDOM.unmountComponentAtNode(container);
+    expect(log).toEqual(['ErrorBoundary componentWillUnmount']);
+  });
+
+  it('catches errors in componentDidMount', () => {
+    var container = document.createElement('div');
+    ReactDOM.render(
+      <ErrorBoundary>
+        <BrokenComponentWillUnmount>
+          <Normal />
+        </BrokenComponentWillUnmount>
+        <BrokenComponentDidMount />
+        <Normal logName="LastChild" />
+      </ErrorBoundary>,
+      container,
+    );
+    expect(log).toEqual([
+      'ErrorBoundary constructor',
+      'ErrorBoundary componentWillMount',
+      'ErrorBoundary render success',
+      'BrokenComponentWillUnmount constructor',
+      'BrokenComponentWillUnmount componentWillMount',
+      'BrokenComponentWillUnmount render',
+      'Normal constructor',
+      'Normal componentWillMount',
+      'Normal render',
+      'BrokenComponentDidMount constructor',
+      'BrokenComponentDidMount componentWillMount',
+      'BrokenComponentDidMount render',
+      'LastChild constructor',
+      'LastChild componentWillMount',
+      'LastChild render',
+      // Start flushing didMount queue
+      'Normal componentDidMount',
+      'BrokenComponentWillUnmount componentDidMount',
+      'BrokenComponentDidMount componentDidMount [!]',
+      // Continue despite the error
+      'LastChild componentDidMount',
+      'ErrorBoundary componentDidMount',
+      // Now we are ready to handle the error
+      // Safely unmount every child
+      'BrokenComponentWillUnmount componentWillUnmount [!]',
+      // Continue unmounting safely despite any errors
+      'Normal componentWillUnmount',
+      'BrokenComponentDidMount componentWillUnmount',
+      'LastChild componentWillUnmount',
+      // Handle the error
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      // The update has finished
+      'ErrorBoundary componentDidUpdate',
+    ]);
+
+    log.length = 0;
+    ReactDOM.unmountComponentAtNode(container);
+    expect(log).toEqual(['ErrorBoundary componentWillUnmount']);
+  });
+
+  it('catches errors in componentDidUpdate', () => {
+    var container = document.createElement('div');
+    ReactDOM.render(
+      <ErrorBoundary>
+        <BrokenComponentDidUpdate />
+      </ErrorBoundary>,
+      container,
+    );
+
+    log.length = 0;
+    ReactDOM.render(
+      <ErrorBoundary>
+        <BrokenComponentDidUpdate />
+      </ErrorBoundary>,
+      container,
+    );
+    expect(log).toEqual([
+      'ErrorBoundary componentWillReceiveProps',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render success',
+      'BrokenComponentDidUpdate componentWillReceiveProps',
+      'BrokenComponentDidUpdate componentWillUpdate',
+      'BrokenComponentDidUpdate render',
+      // All lifecycles run
+      'BrokenComponentDidUpdate componentDidUpdate [!]',
+      'ErrorBoundary componentDidUpdate',
+      'BrokenComponentDidUpdate componentWillUnmount',
+      // Then, error is handled
+      'ErrorBoundary componentDidCatch',
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
+    ]);
+
+    log.length = 0;
+    ReactDOM.unmountComponentAtNode(container);
+    expect(log).toEqual(['ErrorBoundary componentWillUnmount']);
+  });
+
+  it('propagates errors inside boundary during componentDidMount', () => {
+    var container = document.createElement('div');
+    ReactDOM.render(
+      <ErrorBoundary>
+        <BrokenComponentDidMountErrorBoundary
+          renderError={error => (
+            <div>
+              We should never catch our own error: {error.message}.
+            </div>
+          )}
+        />
+      </ErrorBoundary>,
+      container,
+    );
+    expect(container.firstChild.textContent).toBe('Caught an error: Hello.');
+    expect(log).toEqual([
+      'ErrorBoundary constructor',
+      'ErrorBoundary componentWillMount',
+      'ErrorBoundary render success',
+      'BrokenComponentDidMountErrorBoundary constructor',
+      'BrokenComponentDidMountErrorBoundary componentWillMount',
+      'BrokenComponentDidMountErrorBoundary render success',
+      'BrokenComponentDidMountErrorBoundary componentDidMount [!]',
+      // Fiber proceeds with the hooks
+      'ErrorBoundary componentDidMount',
+      'BrokenComponentDidMountErrorBoundary componentWillUnmount',
+      // The error propagates to the higher boundary
+      'ErrorBoundary componentDidCatch',
+      // Fiber retries from the root
+      'ErrorBoundary componentWillUpdate',
+      'ErrorBoundary render error',
+      'ErrorBoundary componentDidUpdate',
+    ]);
+
+    log.length = 0;
+    ReactDOM.unmountComponentAtNode(container);
+    expect(log).toEqual(['ErrorBoundary componentWillUnmount']);
+  });
+
+  it('lets different boundaries catch their own first errors', () => {
+    function renderUnmountError(error) {
+      return <div>Caught an unmounting error: {error.message}.</div>;
+    }
+    function renderUpdateError(error) {
+      return <div>Caught an updating error: {error.message}.</div>;
+    }
+
+    var container = document.createElement('div');
+    ReactDOM.render(
+      <ErrorBoundary logName="OuterErrorBoundary">
+        <ErrorBoundary
+          logName="InnerUnmountBoundary"
+          renderError={renderUnmountError}>
+          <BrokenComponentWillUnmount errorText="E1" />
+          <BrokenComponentWillUnmount errorText="E2" />
+        </ErrorBoundary>
+        <ErrorBoundary
+          logName="InnerUpdateBoundary"
+          renderError={renderUpdateError}>
+          <BrokenComponentDidUpdate errorText="E3" />
+          <BrokenComponentDidUpdate errorText="E4" />
+        </ErrorBoundary>
+      </ErrorBoundary>,
+      container,
+    );
+
+    log.length = 0;
+    ReactDOM.render(
+      <ErrorBoundary logName="OuterErrorBoundary">
+        <ErrorBoundary
+          logName="InnerUnmountBoundary"
+          renderError={renderUnmountError}
+        />
+        <ErrorBoundary
+          logName="InnerUpdateBoundary"
+          renderError={renderUpdateError}>
+          <BrokenComponentDidUpdate errorText="E3" />
+          <BrokenComponentDidUpdate errorText="E4" />
+        </ErrorBoundary>
+      </ErrorBoundary>,
+      container,
+    );
+
+    expect(container.firstChild.textContent).toBe(
+      'Caught an unmounting error: E1.' + 'Caught an updating error: E3.',
+    );
+    expect(log).toEqual([
+      // Begin update phase
+      'OuterErrorBoundary componentWillReceiveProps',
+      'OuterErrorBoundary componentWillUpdate',
+      'OuterErrorBoundary render success',
+      'InnerUnmountBoundary componentWillReceiveProps',
+      'InnerUnmountBoundary componentWillUpdate',
+      'InnerUnmountBoundary render success',
+      'InnerUpdateBoundary componentWillReceiveProps',
+      'InnerUpdateBoundary componentWillUpdate',
+      'InnerUpdateBoundary render success',
+      // First come the updates
+      'BrokenComponentDidUpdate componentWillReceiveProps',
+      'BrokenComponentDidUpdate componentWillUpdate',
+      'BrokenComponentDidUpdate render',
+      'BrokenComponentDidUpdate componentWillReceiveProps',
+      'BrokenComponentDidUpdate componentWillUpdate',
+      'BrokenComponentDidUpdate render',
+      // We're in commit phase now, deleting
+      'BrokenComponentWillUnmount componentWillUnmount [!]',
+      'BrokenComponentWillUnmount componentWillUnmount [!]',
+      // Continue despite errors, handle them after commit is done
+      'InnerUnmountBoundary componentDidUpdate',
+      // We're still in commit phase, now calling update lifecycles
+      'BrokenComponentDidUpdate componentDidUpdate [!]',
+      // Again, continue despite errors, we'll handle them later
+      'BrokenComponentDidUpdate componentDidUpdate [!]',
+      'InnerUpdateBoundary componentDidUpdate',
+      'OuterErrorBoundary componentDidUpdate',
+      // After the commit phase, attempt to recover from any errors that
+      // were captured
+      'BrokenComponentDidUpdate componentWillUnmount',
+      'BrokenComponentDidUpdate componentWillUnmount',
+      'InnerUnmountBoundary componentDidCatch',
+      'InnerUpdateBoundary componentDidCatch',
+      'InnerUnmountBoundary componentWillUpdate',
+      'InnerUnmountBoundary render error',
+      'InnerUpdateBoundary componentWillUpdate',
+      'InnerUpdateBoundary render error',
+      'InnerUnmountBoundary componentDidUpdate',
+      'InnerUpdateBoundary componentDidUpdate',
+    ]);
+
+    log.length = 0;
+    ReactDOM.unmountComponentAtNode(container);
+    expect(log).toEqual([
+      'OuterErrorBoundary componentWillUnmount',
+      'InnerUnmountBoundary componentWillUnmount',
+      'InnerUpdateBoundary componentWillUnmount',
+    ]);
+  });
+
+  it('discards a bad root if the root component fails', () => {
+    spyOn(console, 'error');
+
+    const X = null;
+    const Y = undefined;
+    let err1;
+    let err2;
+
+    try {
+      let container = document.createElement('div');
+      ReactDOM.render(<X />, container);
+    } catch (err) {
+      err1 = err;
+    }
+    try {
+      let container = document.createElement('div');
+      ReactDOM.render(<Y />, container);
+    } catch (err) {
+      err2 = err;
+    }
+
+    expect(err1.message).toMatch(/got: null/);
+    expect(err2.message).toMatch(/got: undefined/);
+  });
+
+  it('renders empty output if error boundary does not handle the error', () => {
+    var container = document.createElement('div');
+    ReactDOM.render(
+      <div>
+        Sibling
+        <NoopErrorBoundary>
+          <BrokenRender />
+        </NoopErrorBoundary>
+      </div>,
+      container,
+    );
+    expect(container.firstChild.textContent).toBe('Sibling');
+    expect(log).toEqual([
+      'NoopErrorBoundary constructor',
+      'NoopErrorBoundary componentWillMount',
+      'NoopErrorBoundary render',
+      'BrokenRender constructor',
+      'BrokenRender componentWillMount',
+      'BrokenRender render [!]',
+      // In Fiber, noop error boundaries render null
+      'NoopErrorBoundary componentDidMount',
+      'NoopErrorBoundary componentDidCatch',
+      // Nothing happens.
+    ]);
+
+    log.length = 0;
+    ReactDOM.unmountComponentAtNode(container);
+    expect(log).toEqual(['NoopErrorBoundary componentWillUnmount']);
+  });
+
+  it('passes first error when two errors happen in commit', () => {
+    const errors = [];
+    let caughtError;
+    class Parent extends React.Component {
+      render() {
+        return <Child />;
       }
-      class Child extends React.Component {
-        render() {
-          return <div />;
-        }
-        componentDidMount() {
-          errors.push('child sad');
-          throw new Error('child sad');
-        }
+      componentDidMount() {
+        errors.push('parent sad');
+        throw new Error('parent sad');
       }
-
-      var container = document.createElement('div');
-      try {
-        // Here, we test the behavior where there is no error boundary and we
-        // delegate to the host root.
-        ReactDOM.render(<Parent />, container);
-      } catch (e) {
-        if (e.message !== 'parent sad' && e.message !== 'child sad') {
-          throw e;
-        }
-        caughtError = e;
+    }
+    class Child extends React.Component {
+      render() {
+        return <div />;
+      }
+      componentDidMount() {
+        errors.push('child sad');
+        throw new Error('child sad');
       }
+    }
 
-      expect(errors).toEqual(['child sad', 'parent sad']);
-      // Error should be the first thrown
-      expect(caughtError.message).toBe('child sad');
-    });
-  }
+    var container = document.createElement('div');
+    try {
+      // Here, we test the behavior where there is no error boundary and we
+      // delegate to the host root.
+      ReactDOM.render(<Parent />, container);
+    } catch (e) {
+      if (e.message !== 'parent sad' && e.message !== 'child sad') {
+        throw e;
+      }
+      caughtError = e;
+    }
+
+    expect(errors).toEqual(['child sad', 'parent sad']);
+    // Error should be the first thrown
+    expect(caughtError.message).toBe('child sad');
+  });
 });
diff --git a/src/renderers/__tests__/ReactHostOperationHistoryHook-test.js b/src/renderers/__tests__/ReactHostOperationHistoryHook-test.js
deleted file mode 100644
index fa43369f8df..00000000000
--- a/src/renderers/__tests__/ReactHostOperationHistoryHook-test.js
+++ /dev/null
@@ -1,781 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @emails react-core
- */
-
-'use strict';
-
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-var describeStack = ReactDOMFeatureFlags.useFiber ? describe.skip : describe;
-
-// This is only used by ReactPerf which is currently not supported on Fiber.
-// Use browser timeline integration instead.
-describeStack('ReactHostOperationHistoryHook', () => {
-  var React;
-  var ReactPerf;
-  var ReactDOM;
-  var ReactDOMComponentTree;
-  var ReactHostOperationHistoryHook;
-
-  beforeEach(() => {
-    jest.resetModules();
-
-    React = require('react');
-    ReactPerf = require('ReactPerf');
-    ReactDOM = require('react-dom');
-    ReactDOMComponentTree = require('ReactDOMComponentTree');
-    ReactHostOperationHistoryHook = require('ReactHostOperationHistoryHook');
-
-    ReactPerf.start();
-  });
-
-  afterEach(() => {
-    ReactPerf.stop();
-  });
-
-  function assertHistoryMatches(expectedHistory) {
-    var actualHistory = ReactHostOperationHistoryHook.getHistory();
-    expectDev(actualHistory).toEqual(expectedHistory);
-  }
-
-  describe('mount', () => {
-    it('gets recorded for host roots', () => {
-      var node = document.createElement('div');
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<div><p>Hi.</p></div>, node);
-
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'mount',
-          payload: 'DIV',
-        },
-      ]);
-    });
-
-    it('gets recorded for composite roots', () => {
-      function Foo() {
-        return <div><p>Hi.</p></div>;
-      }
-      var node = document.createElement('div');
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<Foo />, node);
-
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'mount',
-          payload: 'DIV',
-        },
-      ]);
-    });
-
-    it('gets ignored for composite roots that return null', () => {
-      function Foo() {
-        return null;
-      }
-      var node = document.createElement('div');
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<Foo />, node);
-
-      // Empty DOM components should be invisible to hooks.
-      assertHistoryMatches([]);
-    });
-
-    it('gets recorded when a native is mounted deeply instead of null', () => {
-      var element;
-      function Foo() {
-        return element;
-      }
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-
-      var node = document.createElement('div');
-      element = null;
-      ReactDOM.render(<Foo />, node);
-
-      element = <span />;
-      ReactDOM.render(<Foo />, node);
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-      // Since empty components should be invisible to hooks,
-      // we record a "mount" event rather than a "replace with".
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'mount',
-          payload: 'SPAN',
-        },
-      ]);
-    });
-  });
-
-  describe('update styles', () => {
-    it('gets recorded during mount', () => {
-      var node = document.createElement('div');
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(
-        <div
-          style={{
-            color: 'red',
-            backgroundColor: 'yellow',
-          }}
-        />,
-        node,
-      );
-
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'update styles',
-          payload: {
-            color: 'red',
-            backgroundColor: 'yellow',
-          },
-        },
-        {
-          instanceID: inst._debugID,
-          type: 'mount',
-          payload: 'DIV',
-        },
-      ]);
-    });
-
-    it('gets recorded during an update', () => {
-      var node = document.createElement('div');
-      ReactDOM.render(<div />, node);
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<div style={{color: 'red'}} />, node);
-      ReactDOM.render(
-        <div
-          style={{
-            color: 'blue',
-            backgroundColor: 'yellow',
-          }}
-        />,
-        node,
-      );
-      ReactDOM.render(<div style={{backgroundColor: 'green'}} />, node);
-      ReactDOM.render(<div />, node);
-
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'update styles',
-          payload: {color: 'red'},
-        },
-        {
-          instanceID: inst._debugID,
-          type: 'update styles',
-          payload: {color: 'blue', backgroundColor: 'yellow'},
-        },
-        {
-          instanceID: inst._debugID,
-          type: 'update styles',
-          payload: {color: '', backgroundColor: 'green'},
-        },
-        {
-          instanceID: inst._debugID,
-          type: 'update styles',
-          payload: {backgroundColor: ''},
-        },
-      ]);
-    });
-
-    it('gets ignored if the styles are shallowly equal', () => {
-      var node = document.createElement('div');
-      ReactDOM.render(<div />, node);
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(
-        <div
-          style={{
-            color: 'red',
-            backgroundColor: 'yellow',
-          }}
-        />,
-        node,
-      );
-      ReactDOM.render(
-        <div
-          style={{
-            color: 'red',
-            backgroundColor: 'yellow',
-          }}
-        />,
-        node,
-      );
-
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'update styles',
-          payload: {
-            color: 'red',
-            backgroundColor: 'yellow',
-          },
-        },
-      ]);
-    });
-  });
-
-  describe('update attribute', () => {
-    describe('simple attribute', () => {
-      it('gets recorded during mount', () => {
-        var node = document.createElement('div');
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div className="rad" tabIndex={42} />, node);
-
-        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-        assertHistoryMatches([
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {className: 'rad'},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {tabIndex: 42},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'mount',
-            payload: 'DIV',
-          },
-        ]);
-      });
-
-      it('gets recorded during an update', () => {
-        var node = document.createElement('div');
-        ReactDOM.render(<div />, node);
-        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div className="rad" />, node);
-        ReactDOM.render(<div className="mad" tabIndex={42} />, node);
-        ReactDOM.render(<div tabIndex={43} />, node);
-
-        assertHistoryMatches([
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {className: 'rad'},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {className: 'mad'},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {tabIndex: 42},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'remove attribute',
-            payload: 'className',
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {tabIndex: 43},
-          },
-        ]);
-      });
-    });
-
-    describe('attribute that gets removed with certain values', () => {
-      it('gets recorded as a removal during an update', () => {
-        var node = document.createElement('div');
-        ReactDOM.render(<div />, node);
-        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div disabled={true} />, node);
-        ReactDOM.render(<div disabled={false} />, node);
-
-        assertHistoryMatches([
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {disabled: true},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'remove attribute',
-            payload: 'disabled',
-          },
-        ]);
-      });
-    });
-
-    describe('custom attribute', () => {
-      it('gets recorded during mount', () => {
-        var node = document.createElement('div');
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div data-x="rad" data-y={42} />, node);
-
-        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-        assertHistoryMatches([
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {'data-x': 'rad'},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {'data-y': 42},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'mount',
-            payload: 'DIV',
-          },
-        ]);
-      });
-
-      it('gets recorded during an update', () => {
-        var node = document.createElement('div');
-        ReactDOM.render(<div />, node);
-        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div data-x="rad" />, node);
-        ReactDOM.render(<div data-x="mad" data-y={42} />, node);
-        ReactDOM.render(<div data-y={43} />, node);
-
-        assertHistoryMatches([
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {'data-x': 'rad'},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {'data-x': 'mad'},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {'data-y': 42},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'remove attribute',
-            payload: 'data-x',
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {'data-y': 43},
-          },
-        ]);
-      });
-    });
-
-    describe('attribute on a web component', () => {
-      it('gets recorded during mount', () => {
-        var node = document.createElement('div');
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<my-component className="rad" tabIndex={42} />, node);
-
-        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-        assertHistoryMatches([
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {className: 'rad'},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {tabIndex: 42},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'mount',
-            payload: 'MY-COMPONENT',
-          },
-        ]);
-      });
-
-      it('gets recorded during an update', () => {
-        var node = document.createElement('div');
-        ReactDOM.render(<my-component />, node);
-        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<my-component className="rad" />, node);
-        ReactDOM.render(<my-component className="mad" tabIndex={42} />, node);
-        ReactDOM.render(<my-component tabIndex={43} />, node);
-
-        assertHistoryMatches([
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {className: 'rad'},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {className: 'mad'},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {tabIndex: 42},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'remove attribute',
-            payload: 'className',
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'update attribute',
-            payload: {tabIndex: 43},
-          },
-        ]);
-      });
-    });
-  });
-
-  describe('replace text', () => {
-    describe('text content', () => {
-      it('gets recorded during an update from text content', () => {
-        var node = document.createElement('div');
-        ReactDOM.render(<div>Hi.</div>, node);
-        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div>Bye.</div>, node);
-
-        assertHistoryMatches([
-          {
-            instanceID: inst._debugID,
-            type: 'replace text',
-            payload: 'Bye.',
-          },
-        ]);
-      });
-
-      it('gets recorded during an update from html', () => {
-        var node = document.createElement('div');
-        ReactDOM.render(
-          <div dangerouslySetInnerHTML={{__html: 'Hi.'}} />,
-          node,
-        );
-        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div>Bye.</div>, node);
-
-        assertHistoryMatches([
-          {
-            instanceID: inst._debugID,
-            type: 'replace text',
-            payload: 'Bye.',
-          },
-        ]);
-      });
-
-      it('gets recorded during an update from children', () => {
-        var node = document.createElement('div');
-        ReactDOM.render(<div><span /><p /></div>, node);
-        var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div>Bye.</div>, node);
-
-        assertHistoryMatches([
-          {
-            instanceID: inst._debugID,
-            type: 'remove child',
-            payload: {fromIndex: 0},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'remove child',
-            payload: {fromIndex: 1},
-          },
-          {
-            instanceID: inst._debugID,
-            type: 'replace text',
-            payload: 'Bye.',
-          },
-        ]);
-      });
-
-      it('gets ignored if new text is equal', () => {
-        var node = document.createElement('div');
-        ReactDOM.render(<div>Hi.</div>, node);
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div>Hi.</div>, node);
-
-        assertHistoryMatches([]);
-      });
-    });
-
-    describe('text node', () => {
-      it('gets recorded during an update', () => {
-        var node = document.createElement('div');
-        ReactDOM.render(<div>{'Hi.'}{42}</div>, node);
-        var inst1 = ReactDOMComponentTree.getInstanceFromNode(
-          node.firstChild.childNodes[0],
-        );
-        var inst2 = ReactDOMComponentTree.getInstanceFromNode(
-          node.firstChild.childNodes[3],
-        );
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div>{'Bye.'}{43}</div>, node);
-
-        assertHistoryMatches([
-          {
-            instanceID: inst1._debugID,
-            type: 'replace text',
-            payload: 'Bye.',
-          },
-          {
-            instanceID: inst2._debugID,
-            type: 'replace text',
-            payload: '43',
-          },
-        ]);
-      });
-
-      it('gets ignored if new text is equal', () => {
-        var node = document.createElement('div');
-        ReactDOM.render(<div>{'Hi.'}{42}</div>, node);
-
-        ReactHostOperationHistoryHook._preventClearing = true;
-        ReactDOM.render(<div>{'Hi.'}{42}</div>, node);
-
-        assertHistoryMatches([]);
-      });
-    });
-  });
-
-  describe('replace with', () => {
-    it('gets recorded when composite renders to a different type', () => {
-      var element;
-      function Foo() {
-        return element;
-      }
-
-      var node = document.createElement('div');
-      element = <div />;
-      ReactDOM.render(<Foo />, node);
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-      element = <span />;
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<Foo />, node);
-
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'replace with',
-          payload: 'SPAN',
-        },
-      ]);
-    });
-
-    it('gets recorded when composite renders to null after a native', () => {
-      var element;
-      function Foo() {
-        return element;
-      }
-
-      var node = document.createElement('div');
-      element = <span />;
-      ReactDOM.render(<Foo />, node);
-
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-      element = null;
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<Foo />, node);
-
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'replace with',
-          payload: '#comment',
-        },
-      ]);
-    });
-
-    it('gets ignored if the type has not changed', () => {
-      var element;
-      function Foo() {
-        return element;
-      }
-
-      var node = document.createElement('div');
-      element = <div />;
-      ReactDOM.render(<Foo />, node);
-
-      element = <div />;
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<Foo />, node);
-
-      assertHistoryMatches([]);
-    });
-  });
-
-  describe('replace children', () => {
-    it('gets recorded during an update from text content', () => {
-      var node = document.createElement('div');
-      ReactDOM.render(<div>Hi.</div>, node);
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<div dangerouslySetInnerHTML={{__html: 'Bye.'}} />, node);
-
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'replace children',
-          payload: 'Bye.',
-        },
-      ]);
-    });
-
-    it('gets recorded during an update from html', () => {
-      var node = document.createElement('div');
-      ReactDOM.render(<div dangerouslySetInnerHTML={{__html: 'Hi.'}} />, node);
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<div dangerouslySetInnerHTML={{__html: 'Bye.'}} />, node);
-
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'replace children',
-          payload: 'Bye.',
-        },
-      ]);
-    });
-
-    it('gets recorded during an update from children', () => {
-      var node = document.createElement('div');
-      ReactDOM.render(<div><span /><p /></div>, node);
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<div dangerouslySetInnerHTML={{__html: 'Hi.'}} />, node);
-
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'remove child',
-          payload: {fromIndex: 0},
-        },
-        {
-          instanceID: inst._debugID,
-          type: 'remove child',
-          payload: {fromIndex: 1},
-        },
-        {
-          instanceID: inst._debugID,
-          type: 'replace children',
-          payload: 'Hi.',
-        },
-      ]);
-    });
-
-    it('gets ignored if new html is equal', () => {
-      var node = document.createElement('div');
-      ReactDOM.render(<div dangerouslySetInnerHTML={{__html: 'Hi.'}} />, node);
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<div dangerouslySetInnerHTML={{__html: 'Hi.'}} />, node);
-
-      assertHistoryMatches([]);
-    });
-  });
-
-  describe('insert child', () => {
-    it('gets reported when a child is inserted', () => {
-      var node = document.createElement('div');
-      ReactDOM.render(<div><span /></div>, node);
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<div><span /><p /></div>, node);
-
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'insert child',
-          payload: {toIndex: 1, content: 'P'},
-        },
-      ]);
-    });
-  });
-
-  describe('move child', () => {
-    it('gets reported when a child is inserted', () => {
-      var node = document.createElement('div');
-      ReactDOM.render(<div><span key="a" /><p key="b" /></div>, node);
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<div><p key="b" /><span key="a" /></div>, node);
-
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'move child',
-          payload: {fromIndex: 0, toIndex: 1},
-        },
-      ]);
-    });
-  });
-
-  describe('remove child', () => {
-    it('gets reported when a child is removed', () => {
-      var node = document.createElement('div');
-      ReactDOM.render(<div><span key="a" /><p key="b" /></div>, node);
-      var inst = ReactDOMComponentTree.getInstanceFromNode(node.firstChild);
-
-      ReactHostOperationHistoryHook._preventClearing = true;
-      ReactDOM.render(<div><span key="a" /></div>, node);
-
-      assertHistoryMatches([
-        {
-          instanceID: inst._debugID,
-          type: 'remove child',
-          payload: {fromIndex: 1},
-        },
-      ]);
-    });
-  });
-});
diff --git a/src/renderers/__tests__/ReactMultiChild-test.js b/src/renderers/__tests__/ReactMultiChild-test.js
index cdf104ba3b3..c8cd520d63f 100644
--- a/src/renderers/__tests__/ReactMultiChild-test.js
+++ b/src/renderers/__tests__/ReactMultiChild-test.js
@@ -18,13 +18,11 @@ describe('ReactMultiChild', () => {
 
   var React;
   var ReactDOM;
-  var ReactDOMFeatureFlags;
 
   beforeEach(() => {
     jest.resetModules();
     React = require('react');
     ReactDOM = require('react-dom');
-    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
   });
 
   describe('reconciliation', () => {
@@ -282,8 +280,7 @@ describe('ReactMultiChild', () => {
       'Warning: Using Maps as children is unsupported and will likely yield ' +
         'unexpected results. Convert it to a sequence/iterable of keyed ' +
         'ReactElements instead.\n' +
-        // Fiber gives a slightly better stack with the nearest host components
-        (ReactDOMFeatureFlags.useFiber ? '    in div (at **)\n' : '') +
+        '    in div (at **)\n' +
         '    in Parent (at **)',
     );
   });
@@ -370,23 +367,12 @@ describe('ReactMultiChild', () => {
       'oneA componentDidMount',
       'twoA componentDidMount',
 
-      ...(ReactDOMFeatureFlags.useFiber
-        ? [
-            'oneB componentWillMount',
-            'oneB render',
-            'twoB componentWillMount',
-            'twoB render',
-            'oneA componentWillUnmount',
-            'twoA componentWillUnmount',
-          ]
-        : [
-            'oneB componentWillMount',
-            'oneB render',
-            'oneA componentWillUnmount',
-            'twoB componentWillMount',
-            'twoB render',
-            'twoA componentWillUnmount',
-          ]),
+      'oneB componentWillMount',
+      'oneB render',
+      'twoB componentWillMount',
+      'twoB render',
+      'oneA componentWillUnmount',
+      'twoA componentWillUnmount',
 
       'oneB componentDidMount',
       'twoB componentDidMount',
diff --git a/src/renderers/__tests__/ReactMultiChildText-test.js b/src/renderers/__tests__/ReactMultiChildText-test.js
index 53daf581353..e4fcca19a74 100644
--- a/src/renderers/__tests__/ReactMultiChildText-test.js
+++ b/src/renderers/__tests__/ReactMultiChildText-test.js
@@ -13,7 +13,6 @@
 
 var React = require('react');
 var ReactDOM = require('react-dom');
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 var ReactTestUtils = require('react-dom/test-utils');
 
 // Helpers
@@ -50,43 +49,16 @@ var expectChildren = function(container, children) {
       expect(textNode.data).toBe('' + children);
     }
   } else {
-    var openingCommentNode;
-    var closingCommentNode;
     var mountIndex = 0;
 
     for (var i = 0; i < children.length; i++) {
       var child = children[i];
 
       if (typeof child === 'string') {
-        if (ReactDOMFeatureFlags.useFiber) {
-          textNode = outerNode.childNodes[mountIndex];
-          expect(textNode.nodeType).toBe(3);
-          expect(textNode.data).toBe('' + child);
-          mountIndex++;
-        } else {
-          openingCommentNode = outerNode.childNodes[mountIndex];
-
-          expect(openingCommentNode.nodeType).toBe(8);
-          expect(openingCommentNode.nodeValue).toMatch(/ react-text: [0-9]+ /);
-
-          if (child === '') {
-            textNode = null;
-            closingCommentNode = openingCommentNode.nextSibling;
-            mountIndex += 2;
-          } else {
-            textNode = openingCommentNode.nextSibling;
-            closingCommentNode = textNode.nextSibling;
-            mountIndex += 3;
-          }
-
-          if (textNode) {
-            expect(textNode.nodeType).toBe(3);
-            expect(textNode.data).toBe('' + child);
-          }
-
-          expect(closingCommentNode.nodeType).toBe(8);
-          expect(closingCommentNode.nodeValue).toBe(' /react-text ');
-        }
+        textNode = outerNode.childNodes[mountIndex];
+        expect(textNode.nodeType).toBe(3);
+        expect(textNode.data).toBe('' + child);
+        mountIndex++;
       } else {
         var elementDOMNode = outerNode.childNodes[mountIndex];
         expect(elementDOMNode.tagName).toBe('DIV');
@@ -191,20 +163,14 @@ describe('ReactMultiChildText', () => {
       [true, <div>{1.2}{''}{<div />}{'foo'}</div>, true, 1.2], [<div />, '1.2'],
       ['', 'foo', <div>{true}{<div />}{1.2}{''}</div>, 'foo'], ['', 'foo', <div />, 'foo'],
     ]);
-    if (ReactDOMFeatureFlags.useFiber) {
-      expectDev(console.error.calls.count()).toBe(2);
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'Warning: Each child in an array or iterator should have a unique "key" prop.',
-      );
-      expectDev(console.error.calls.argsFor(1)[0]).toContain(
-        'Warning: Each child in an array or iterator should have a unique "key" prop.',
-      );
-    } else {
-      expectDev(console.error.calls.count()).toBe(1);
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'Warning: Each child in an array or iterator should have a unique "key" prop.',
-      );
-    }
+
+    expectDev(console.error.calls.count()).toBe(2);
+    expectDev(console.error.calls.argsFor(0)[0]).toContain(
+      'Warning: Each child in an array or iterator should have a unique "key" prop.',
+    );
+    expectDev(console.error.calls.argsFor(1)[0]).toContain(
+      'Warning: Each child in an array or iterator should have a unique "key" prop.',
+    );
   });
 
   it('should throw if rendering both HTML and children', () => {
diff --git a/src/renderers/__tests__/ReactPerf-test.js b/src/renderers/__tests__/ReactPerf-test.js
deleted file mode 100644
index 40d76b81207..00000000000
--- a/src/renderers/__tests__/ReactPerf-test.js
+++ /dev/null
@@ -1,746 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @emails react-core
- */
-
-'use strict';
-
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-var describeStack = ReactDOMFeatureFlags.useFiber ? describe.skip : describe;
-
-// ReactPerf is currently not supported on Fiber.
-// Use browser timeline integration instead.
-describeStack('ReactPerf', () => {
-  var React;
-  var ReactDOM;
-  var ReactPerf;
-  var ReactTestUtils;
-  var emptyFunction;
-
-  var App;
-  var Box;
-  var Div;
-  var LifeCycle;
-
-  beforeEach(() => {
-    var now = 0;
-    jest.setMock('fbjs/lib/performanceNow', function() {
-      return now++;
-    });
-
-    if (typeof console.table !== 'function') {
-      console.table = () => {};
-      console.table.isFake = true;
-    }
-
-    React = require('react');
-    ReactDOM = require('react-dom');
-    ReactPerf = require('ReactPerf');
-    ReactTestUtils = require('react-dom/test-utils');
-    emptyFunction = require('fbjs/lib/emptyFunction');
-
-    App = class extends React.Component {
-      render() {
-        return <div><Box /><Box flip={this.props.flipSecond} /></div>;
-      }
-    };
-
-    Box = class extends React.Component {
-      render() {
-        return <div key={!!this.props.flip}><input /></div>;
-      }
-    };
-
-    // ReactPerf only measures composites, so we put everything in one.
-    Div = class extends React.Component {
-      render() {
-        return <div {...this.props} />;
-      }
-    };
-
-    LifeCycle = class extends React.Component {
-      shouldComponentUpdate = emptyFunction.thatReturnsTrue;
-      componentWillMount = emptyFunction;
-      componentDidMount = emptyFunction;
-      componentWillReceiveProps = emptyFunction;
-      componentWillUpdate = emptyFunction;
-      componentDidUpdate = emptyFunction;
-      componentWillUnmount = emptyFunction;
-      render = emptyFunction.thatReturnsNull;
-    };
-  });
-
-  afterEach(() => {
-    if (console.table.isFake) {
-      delete console.table;
-    }
-  });
-
-  function measure(fn) {
-    ReactPerf.start();
-    fn();
-    ReactPerf.stop();
-
-    // Make sure none of the methods crash.
-    ReactPerf.getWasted();
-    ReactPerf.getInclusive();
-    ReactPerf.getExclusive();
-    ReactPerf.getOperations();
-
-    return ReactPerf.getLastMeasurements();
-  }
-
-  it('should count no-op update as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<App />, container);
-    var measurements = measure(() => {
-      ReactDOM.render(<App />, container);
-    });
-
-    var summary = ReactPerf.getWasted(measurements);
-    expect(summary).toEqual([
-      {
-        key: 'App',
-        instanceCount: 1,
-        inclusiveRenderDuration: 3,
-        renderCount: 1,
-      },
-      {
-        key: 'App > Box',
-        instanceCount: 2,
-        inclusiveRenderDuration: 2,
-        renderCount: 2,
-      },
-    ]);
-  });
-
-  it('should count no-op update in child as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<App />, container);
-
-    // Here, we add a Box -- two of the <Box /> updates are wasted time (but the
-    // addition of the third is not)
-    var measurements = measure(() => {
-      ReactDOM.render(<App flipSecond={true} />, container);
-    });
-
-    var summary = ReactPerf.getWasted(measurements);
-    expect(summary).toEqual([
-      {
-        key: 'App > Box',
-        instanceCount: 1,
-        inclusiveRenderDuration: 1,
-        renderCount: 1,
-      },
-    ]);
-  });
-
-  function expectNoWaste(fn) {
-    var measurements = measure(fn);
-    var summary = ReactPerf.getWasted(measurements);
-    expect(summary).toEqual([]);
-  }
-
-  it('should not count initial render as waste', () => {
-    expectNoWaste(() => {
-      ReactTestUtils.renderIntoDocument(<App />);
-    });
-  });
-
-  it('should not count unmount as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<Div>hello</Div>, container);
-    expectNoWaste(() => {
-      ReactDOM.unmountComponentAtNode(container);
-    });
-  });
-
-  it('should not count content update as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<Div>hello</Div>, container);
-    expectNoWaste(() => {
-      ReactDOM.render(<Div>hello world</Div>, container);
-    });
-  });
-
-  it('should not count child addition as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<Div><span /></Div>, container);
-    expectNoWaste(() => {
-      ReactDOM.render(<Div><span /><span /></Div>, container);
-    });
-  });
-
-  it('should not count child removal as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<Div><span /><span /></Div>, container);
-    expectNoWaste(() => {
-      ReactDOM.render(<Div><span /></Div>, container);
-    });
-  });
-
-  it('should not count property update as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<Div className="yellow">hey</Div>, container);
-    expectNoWaste(() => {
-      ReactDOM.render(<Div className="blue">hey</Div>, container);
-    });
-  });
-
-  it('should not count style update as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<Div style={{color: 'yellow'}}>hey</Div>, container);
-    expectNoWaste(() => {
-      ReactDOM.render(<Div style={{color: 'blue'}}>hey</Div>, container);
-    });
-  });
-
-  it('should not count property removal as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<Div className="yellow">hey</Div>, container);
-    expectNoWaste(() => {
-      ReactDOM.render(<Div>hey</Div>, container);
-    });
-  });
-
-  it('should not count raw HTML update as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(
-      <Div dangerouslySetInnerHTML={{__html: 'me'}} />,
-      container,
-    );
-    expectNoWaste(() => {
-      ReactDOM.render(
-        <Div dangerouslySetInnerHTML={{__html: 'you'}} />,
-        container,
-      );
-    });
-  });
-
-  it('should not count child reordering as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<Div><div key="A" /><div key="B" /></Div>, container);
-    expectNoWaste(() => {
-      ReactDOM.render(<Div><div key="B" /><div key="A" /></Div>, container);
-    });
-  });
-
-  it('should not count text update as waste', () => {
-    var container = document.createElement('div');
-    ReactDOM.render(<Div>{'hello'}{'world'}</Div>, container);
-    expectNoWaste(() => {
-      ReactDOM.render(<Div>{'hello'}{'friend'}</Div>, container);
-    });
-  });
-
-  it('should not count replacing null with a host as waste', () => {
-    var element = null;
-    function Foo() {
-      return element;
-    }
-    var container = document.createElement('div');
-    ReactDOM.render(<Foo />, container);
-    expectNoWaste(() => {
-      element = <div />;
-      ReactDOM.render(<Foo />, container);
-    });
-  });
-
-  it('should not count replacing a host with null as waste', () => {
-    var element = <div />;
-    function Foo() {
-      return element;
-    }
-    var container = document.createElement('div');
-    ReactDOM.render(<Foo />, container);
-    expectNoWaste(() => {
-      element = null;
-      ReactDOM.render(<Foo />, container);
-    });
-  });
-
-  it('should include stats for components unmounted during measurement', () => {
-    var container = document.createElement('div');
-    var measurements = measure(() => {
-      ReactDOM.render(<Div><Div key="a" /></Div>, container);
-      ReactDOM.render(<Div><Div key="b" /></Div>, container);
-    });
-    expect(ReactPerf.getExclusive(measurements)).toEqual([
-      {
-        key: 'Div',
-        instanceCount: 3,
-        counts: {ctor: 3, render: 4},
-        durations: {ctor: 3, render: 4},
-        totalDuration: 7,
-      },
-    ]);
-  });
-
-  it('should include lifecycle methods in measurements', () => {
-    var container = document.createElement('div');
-    var measurements = measure(() => {
-      var instance = ReactDOM.render(<LifeCycle />, container);
-      ReactDOM.render(<LifeCycle />, container);
-      instance.setState({});
-      ReactDOM.unmountComponentAtNode(container);
-    });
-    expect(ReactPerf.getExclusive(measurements)).toEqual([
-      {
-        key: 'LifeCycle',
-        instanceCount: 1,
-        totalDuration: 14,
-        counts: {
-          ctor: 1,
-          shouldComponentUpdate: 2,
-          componentWillMount: 1,
-          componentDidMount: 1,
-          componentWillReceiveProps: 1,
-          componentWillUpdate: 2,
-          componentDidUpdate: 2,
-          componentWillUnmount: 1,
-          render: 3,
-        },
-        durations: {
-          ctor: 1,
-          shouldComponentUpdate: 2,
-          componentWillMount: 1,
-          componentDidMount: 1,
-          componentWillReceiveProps: 1,
-          componentWillUpdate: 2,
-          componentDidUpdate: 2,
-          componentWillUnmount: 1,
-          render: 3,
-        },
-      },
-    ]);
-  });
-
-  it('should include render time of functional components', () => {
-    function Foo() {
-      return null;
-    }
-
-    var container = document.createElement('div');
-    var measurements = measure(() => {
-      ReactDOM.render(<Foo />, container);
-    });
-    expect(ReactPerf.getExclusive(measurements)).toEqual([
-      {
-        key: 'Foo',
-        instanceCount: 1,
-        totalDuration: 1,
-        counts: {
-          render: 1,
-        },
-        durations: {
-          render: 1,
-        },
-      },
-    ]);
-  });
-
-  it('should not count time in a portal towards lifecycle method', () => {
-    function Foo() {
-      return null;
-    }
-
-    var portalContainer = document.createElement('div');
-    class Portal extends React.Component {
-      componentDidMount() {
-        ReactDOM.render(<Foo />, portalContainer);
-      }
-      render() {
-        return null;
-      }
-    }
-
-    var container = document.createElement('div');
-    var measurements = measure(() => {
-      ReactDOM.render(<Portal />, container);
-    });
-
-    expect(ReactPerf.getExclusive(measurements)).toEqual([
-      {
-        key: 'Portal',
-        instanceCount: 1,
-        totalDuration: 6,
-        counts: {
-          ctor: 1,
-          componentDidMount: 1,
-          render: 1,
-        },
-        durations: {
-          ctor: 1,
-          // We want to exclude nested imperative ReactDOM.render() from lifecycle hook's own time.
-          // Otherwise it would artificially float to the top even though its exclusive time is small.
-          // This is how we get 4 as a number with the performanceNow() mock:
-          // - we capture the time we enter componentDidMount (n = 0)
-          // - we capture the time when we enter a nested flush (n = 1)
-          // - in the nested flush, we call it twice: before and after <Foo /> rendering. (n = 3)
-          // - we capture the time when we exit a nested flush (n = 4)
-          // - we capture the time we exit componentDidMount (n = 5)
-          // Time spent in componentDidMount = (5 - 0 - (4 - 3)) = 4.
-          componentDidMount: 4,
-          render: 1,
-        },
-      },
-      {
-        key: 'Foo',
-        instanceCount: 1,
-        totalDuration: 1,
-        counts: {
-          render: 1,
-        },
-        durations: {
-          render: 1,
-        },
-      },
-    ]);
-  });
-
-  it('warns once when using getMeasurementsSummaryMap', () => {
-    var measurements = measure(() => {});
-    spyOn(console, 'warn');
-    ReactPerf.getMeasurementsSummaryMap(measurements);
-    expectDev(console.warn.calls.count()).toBe(1);
-    expectDev(console.warn.calls.argsFor(0)[0]).toContain(
-      '`ReactPerf.getMeasurementsSummaryMap(...)` is deprecated. Use ' +
-        '`ReactPerf.getWasted(...)` instead.',
-    );
-
-    ReactPerf.getMeasurementsSummaryMap(measurements);
-    expectDev(console.warn.calls.count()).toBe(1);
-  });
-
-  it('warns once when using printDOM', () => {
-    var measurements = measure(() => {});
-    spyOn(console, 'warn');
-    ReactPerf.printDOM(measurements);
-    expectDev(console.warn.calls.count()).toBe(1);
-    expectDev(console.warn.calls.argsFor(0)[0]).toContain(
-      '`ReactPerf.printDOM(...)` is deprecated. Use ' +
-        '`ReactPerf.printOperations(...)` instead.',
-    );
-
-    ReactPerf.printDOM(measurements);
-    expectDev(console.warn.calls.count()).toBe(1);
-  });
-
-  it('returns isRunning state', () => {
-    expect(ReactPerf.isRunning()).toBe(false);
-
-    ReactPerf.start();
-    expect(ReactPerf.isRunning()).toBe(true);
-
-    ReactPerf.stop();
-    expect(ReactPerf.isRunning()).toBe(false);
-  });
-
-  it('start has no effect when already running', () => {
-    expect(ReactPerf.isRunning()).toBe(false);
-
-    ReactPerf.start();
-    expect(ReactPerf.isRunning()).toBe(true);
-
-    ReactPerf.start();
-    expect(ReactPerf.isRunning()).toBe(true);
-
-    ReactPerf.stop();
-    expect(ReactPerf.isRunning()).toBe(false);
-  });
-
-  it('stop has no effect when already stopped', () => {
-    expect(ReactPerf.isRunning()).toBe(false);
-
-    ReactPerf.stop();
-    expect(ReactPerf.isRunning()).toBe(false);
-
-    ReactPerf.stop();
-    expect(ReactPerf.isRunning()).toBe(false);
-  });
-
-  it('should print console error only once', () => {
-    __DEV__ = false;
-
-    spyOn(console, 'error');
-
-    expect(ReactPerf.getLastMeasurements()).toEqual([]);
-    expect(ReactPerf.getExclusive()).toEqual([]);
-    expect(ReactPerf.getInclusive()).toEqual([]);
-    expect(ReactPerf.getWasted()).toEqual([]);
-    expect(ReactPerf.getOperations()).toEqual([]);
-    expect(ReactPerf.printExclusive()).toEqual(undefined);
-    expect(ReactPerf.printInclusive()).toEqual(undefined);
-    expect(ReactPerf.printWasted()).toEqual(undefined);
-    expect(ReactPerf.printOperations()).toEqual(undefined);
-    expect(ReactPerf.start()).toBe(undefined);
-    expect(ReactPerf.stop()).toBe(undefined);
-    expect(ReactPerf.isRunning()).toBe(false);
-
-    expectDev(console.error.calls.count()).toBe(1);
-
-    __DEV__ = true;
-  });
-
-  it('should work when measurement starts during reconciliation', () => {
-    // https://github.com/facebook/react/issues/6949#issuecomment-230371009
-    class Measurer extends React.Component {
-      componentWillMount() {
-        ReactPerf.start();
-      }
-
-      componentDidMount() {
-        ReactPerf.stop();
-      }
-
-      componentWillUpdate() {
-        ReactPerf.start();
-      }
-
-      componentDidUpdate() {
-        ReactPerf.stop();
-      }
-
-      render() {
-        // Force reconciliation despite constant element
-        return React.cloneElement(this.props.children);
-      }
-    }
-
-    var container = document.createElement('div');
-    ReactDOM.render(<Measurer><App /></Measurer>, container);
-    expect(ReactPerf.getWasted()).toEqual([]);
-
-    ReactDOM.render(<Measurer><App /></Measurer>, container);
-    expect(ReactPerf.getWasted()).toEqual([
-      {
-        key: 'Measurer',
-        instanceCount: 1,
-        inclusiveRenderDuration: 4,
-        renderCount: 1,
-      },
-      {
-        key: 'App',
-        instanceCount: 1,
-        inclusiveRenderDuration: 3,
-        renderCount: 1,
-      },
-      {
-        key: 'App > Box',
-        instanceCount: 2,
-        inclusiveRenderDuration: 2,
-        renderCount: 2,
-      },
-    ]);
-  });
-
-  it('should not print errant warnings if render() throws', () => {
-    var container = document.createElement('div');
-    var thrownErr = new Error('Muhaha!');
-
-    class Evil extends React.Component {
-      render() {
-        throw thrownErr;
-      }
-    }
-
-    ReactPerf.start();
-    try {
-      ReactDOM.render(
-        <div>
-          <LifeCycle />
-          <Evil />
-        </div>,
-        container,
-      );
-    } catch (err) {
-      if (err !== thrownErr) {
-        throw err;
-      }
-    }
-    ReactPerf.stop();
-  });
-
-  it('should not print errant warnings if componentWillMount() throws', () => {
-    var container = document.createElement('div');
-    var thrownErr = new Error('Muhaha!');
-
-    class Evil extends React.Component {
-      componentWillMount() {
-        throw thrownErr;
-      }
-      render() {
-        return <div />;
-      }
-    }
-
-    ReactPerf.start();
-    try {
-      ReactDOM.render(
-        <div>
-          <LifeCycle />
-          <Evil />
-        </div>,
-        container,
-      );
-    } catch (err) {
-      if (err !== thrownErr) {
-        throw err;
-      }
-    }
-    ReactPerf.stop();
-  });
-
-  it('should not print errant warnings if componentDidMount() throws', () => {
-    var container = document.createElement('div');
-    var thrownErr = new Error('Muhaha!');
-
-    class Evil extends React.Component {
-      componentDidMount() {
-        throw thrownErr;
-      }
-      render() {
-        return <div />;
-      }
-    }
-
-    ReactPerf.start();
-    try {
-      ReactDOM.render(
-        <div>
-          <LifeCycle />
-          <Evil />
-        </div>,
-        container,
-      );
-    } catch (err) {
-      if (err !== thrownErr) {
-        throw err;
-      }
-    }
-    ReactPerf.stop();
-  });
-
-  it('should not print errant warnings if portal throws in render()', () => {
-    var container = document.createElement('div');
-    var thrownErr = new Error('Muhaha!');
-
-    class Evil extends React.Component {
-      render() {
-        throw thrownErr;
-      }
-    }
-    class EvilPortal extends React.Component {
-      componentDidMount() {
-        var portalContainer = document.createElement('div');
-        ReactDOM.render(<Evil />, portalContainer);
-      }
-      render() {
-        return <div />;
-      }
-    }
-
-    ReactPerf.start();
-    try {
-      ReactDOM.render(
-        <div>
-          <LifeCycle />
-          <EvilPortal />
-        </div>,
-        container,
-      );
-    } catch (err) {
-      if (err !== thrownErr) {
-        throw err;
-      }
-    }
-    ReactDOM.unmountComponentAtNode(container);
-    ReactPerf.stop();
-  });
-
-  it('should not print errant warnings if portal throws in componentWillMount()', () => {
-    var container = document.createElement('div');
-    var thrownErr = new Error('Muhaha!');
-
-    class Evil extends React.Component {
-      componentWillMount() {
-        throw thrownErr;
-      }
-      render() {
-        return <div />;
-      }
-    }
-    class EvilPortal extends React.Component {
-      componentWillMount() {
-        var portalContainer = document.createElement('div');
-        ReactDOM.render(<Evil />, portalContainer);
-      }
-      render() {
-        return <div />;
-      }
-    }
-
-    ReactPerf.start();
-    try {
-      ReactDOM.render(
-        <div>
-          <LifeCycle />
-          <EvilPortal />
-        </div>,
-        container,
-      );
-    } catch (err) {
-      if (err !== thrownErr) {
-        throw err;
-      }
-    }
-    ReactDOM.unmountComponentAtNode(container);
-    ReactPerf.stop();
-  });
-
-  it('should not print errant warnings if portal throws in componentDidMount()', () => {
-    var container = document.createElement('div');
-    var thrownErr = new Error('Muhaha!');
-
-    class Evil extends React.Component {
-      componentDidMount() {
-        throw thrownErr;
-      }
-      render() {
-        return <div />;
-      }
-    }
-    class EvilPortal extends React.Component {
-      componentDidMount() {
-        var portalContainer = document.createElement('div');
-        ReactDOM.render(<Evil />, portalContainer);
-      }
-      render() {
-        return <div />;
-      }
-    }
-
-    ReactPerf.start();
-    try {
-      ReactDOM.render(
-        <div>
-          <LifeCycle />
-          <EvilPortal />
-        </div>,
-        container,
-      );
-    } catch (err) {
-      if (err !== thrownErr) {
-        throw err;
-      }
-    }
-    ReactDOM.unmountComponentAtNode(container);
-    ReactPerf.stop();
-  });
-});
diff --git a/src/renderers/__tests__/ReactStatelessComponent-test.js b/src/renderers/__tests__/ReactStatelessComponent-test.js
index f3eafc118ee..7df6fccca75 100644
--- a/src/renderers/__tests__/ReactStatelessComponent-test.js
+++ b/src/renderers/__tests__/ReactStatelessComponent-test.js
@@ -16,8 +16,6 @@ var React;
 var ReactDOM;
 var ReactTestUtils;
 
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-
 function StatelessComponent(props) {
   return <div>{props.name}</div>;
 }
@@ -120,43 +118,13 @@ describe('ReactStatelessComponent', () => {
 
     ReactDOM.render(<StatelessComponentWithChildContext name="A" />, container);
 
-    // Stack and Fiber differ in terms of they show warnings
-    if (ReactDOMFeatureFlags.useFiber) {
-      expectDev(console.error.calls.count()).toBe(1);
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'StatelessComponentWithChildContext(...): childContextTypes cannot ' +
-          'be defined on a functional component.',
-      );
-    } else {
-      expectDev(console.error.calls.count()).toBe(2);
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'StatelessComponentWithChildContext(...): childContextTypes cannot ' +
-          'be defined on a functional component.',
-      );
-      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(1)[0])).toBe(
-        'Warning: StatelessComponentWithChildContext.childContextTypes is specified ' +
-          'but there is no getChildContext() method on the instance. You can either ' +
-          'define getChildContext() on StatelessComponentWithChildContext or remove ' +
-          'childContextTypes from it.',
-      );
-    }
+    expectDev(console.error.calls.count()).toBe(1);
+    expectDev(console.error.calls.argsFor(0)[0]).toContain(
+      'StatelessComponentWithChildContext(...): childContextTypes cannot ' +
+        'be defined on a functional component.',
+    );
   });
 
-  if (!ReactDOMFeatureFlags.useFiber) {
-    // Stack doesn't support fragments
-    it('should throw when stateless component returns array', () => {
-      function NotAComponent() {
-        return [<div />, <div />];
-      }
-      expect(function() {
-        ReactTestUtils.renderIntoDocument(<div><NotAComponent /></div>);
-      }).toThrowError(
-        'NotAComponent(...): A valid React element (or null) must be returned. ' +
-          'You may have returned undefined, an array or some other invalid object.',
-      );
-    });
-  }
-
   it('should throw when stateless component returns undefined', () => {
     function NotAComponent() {}
     expect(function() {
diff --git a/src/renderers/__tests__/ReactUpdates-test.js b/src/renderers/__tests__/ReactUpdates-test.js
index 14fe5109d59..14c4d149503 100644
--- a/src/renderers/__tests__/ReactUpdates-test.js
+++ b/src/renderers/__tests__/ReactUpdates-test.js
@@ -14,13 +14,11 @@
 var React;
 var ReactDOM;
 var ReactTestUtils;
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 
 describe('ReactUpdates', () => {
   beforeEach(() => {
     React = require('react');
     ReactDOM = require('react-dom');
-    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
     ReactTestUtils = require('react-dom/test-utils');
   });
 
@@ -521,12 +519,10 @@ describe('ReactUpdates', () => {
       render() {
         var portal = null;
         // If we're using Fiber, we use Portals instead to achieve this.
-        if (ReactDOMFeatureFlags.useFiber) {
-          portal = ReactDOM.unstable_createPortal(
-            <B ref={n => (b = n)} />,
-            bContainer,
-          );
-        }
+        portal = ReactDOM.unstable_createPortal(
+          <B ref={n => (b = n)} />,
+          bContainer,
+        );
         return <div>A{this.state.x}{portal}</div>;
       }
     }
@@ -540,10 +536,6 @@ describe('ReactUpdates', () => {
     }
 
     a = ReactTestUtils.renderIntoDocument(<A />);
-    if (!ReactDOMFeatureFlags.useFiber) {
-      ReactDOM.render(<B ref={n => (b = n)} />, bContainer);
-    }
-
     ReactDOM.unstable_batchedUpdates(function() {
       a.setState({x: 1});
       b.setState({x: 1});
@@ -1159,35 +1151,33 @@ describe('ReactUpdates', () => {
     }).toThrow('Maximum');
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    it('does not fall into an infinite error loop', () => {
-      function BadRender() {
-        throw new Error('error');
-      }
+  it('does not fall into an infinite error loop', () => {
+    function BadRender() {
+      throw new Error('error');
+    }
 
-      class ErrorBoundary extends React.Component {
-        componentDidCatch() {
-          this.props.parent.remount();
-        }
-        render() {
-          return <BadRender />;
-        }
+    class ErrorBoundary extends React.Component {
+      componentDidCatch() {
+        this.props.parent.remount();
+      }
+      render() {
+        return <BadRender />;
       }
+    }
 
-      class NonTerminating extends React.Component {
-        state = {step: 0};
-        remount() {
-          this.setState(state => ({step: state.step + 1}));
-        }
-        render() {
-          return <ErrorBoundary key={this.state.step} parent={this} />;
-        }
+    class NonTerminating extends React.Component {
+      state = {step: 0};
+      remount() {
+        this.setState(state => ({step: state.step + 1}));
       }
+      render() {
+        return <ErrorBoundary key={this.state.step} parent={this} />;
+      }
+    }
 
-      const container = document.createElement('div');
-      expect(() => {
-        ReactDOM.render(<NonTerminating />, container);
-      }).toThrow('Maximum');
-    });
-  }
+    const container = document.createElement('div');
+    expect(() => {
+      ReactDOM.render(<NonTerminating />, container);
+    }).toThrow('Maximum');
+  });
 });
diff --git a/src/renderers/__tests__/multiple-copies-of-react-test.js b/src/renderers/__tests__/multiple-copies-of-react-test.js
index 5151a54dac2..9eb35db6aad 100644
--- a/src/renderers/__tests__/multiple-copies-of-react-test.js
+++ b/src/renderers/__tests__/multiple-copies-of-react-test.js
@@ -12,7 +12,6 @@
 'use strict';
 
 let React = require('react');
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 var ReactTestUtils = require('react-dom/test-utils');
 
 class TextWithStringRef extends React.Component {
@@ -29,23 +28,12 @@ class TextWithStringRef extends React.Component {
 
 describe('when different React version is used with string ref', () => {
   it('throws the "Refs must have owner" warning', () => {
-    if (ReactDOMFeatureFlags.useFiber) {
-      expect(() => {
-        ReactTestUtils.renderIntoDocument(<TextWithStringRef />);
-      }).toThrow(
-        'Element ref was specified as a string (foo) but no owner was set.' +
-          ' You may have multiple copies of React loaded. (details: ' +
-          'https://fb.me/react-refs-must-have-owner).',
-      );
-    } else {
-      expect(() => {
-        ReactTestUtils.renderIntoDocument(<TextWithStringRef />);
-      }).toThrow(
-        'Only a ReactOwner can have refs. You might be adding a ref to a ' +
-          "component that was not created inside a component's `render` " +
-          'method, or you have multiple copies of React loaded ' +
-          '(details: https://fb.me/react-refs-must-have-owner)',
-      );
-    }
+    expect(() => {
+      ReactTestUtils.renderIntoDocument(<TextWithStringRef />);
+    }).toThrow(
+      'Element ref was specified as a string (foo) but no owner was set.' +
+        ' You may have multiple copies of React loaded. (details: ' +
+        'https://fb.me/react-refs-must-have-owner).',
+    );
   });
 });
diff --git a/src/renderers/__tests__/refs-test.js b/src/renderers/__tests__/refs-test.js
index 6f16f2fd34e..cbed01652f8 100644
--- a/src/renderers/__tests__/refs-test.js
+++ b/src/renderers/__tests__/refs-test.js
@@ -12,7 +12,6 @@
 'use strict';
 
 var React = require('react');
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 var ReactTestUtils = require('react-dom/test-utils');
 
 /**
@@ -308,91 +307,6 @@ describe('ref swapping', () => {
   });
 });
 
-describe('string refs between fiber and stack', () => {
-  beforeEach(() => {
-    jest.resetModules();
-    React = require('react');
-    ReactTestUtils = require('react-dom/test-utils');
-  });
-
-  it('attaches, detaches from fiber component with stack layer', () => {
-    const ReactCurrentOwner = require('ReactCurrentOwner');
-
-    const ReactDOMStack = require('ReactDOMStackEntry');
-    const ReactDOMFiber = require('ReactDOMFiberEntry');
-    const ReactInstanceMap = require('ReactInstanceMap');
-    let layerMounted = false;
-    class A extends React.Component {
-      render() {
-        return <div />;
-      }
-      componentDidMount() {
-        // ReactLayeredComponentMixin sets ReactCurrentOwner manually
-        ReactCurrentOwner.current = ReactInstanceMap.get(this);
-        const span = <span ref="span" />;
-        ReactCurrentOwner.current = null;
-
-        ReactDOMStack.unstable_renderSubtreeIntoContainer(
-          this,
-          span,
-          (this._container = document.createElement('div')),
-          () => {
-            expect(this.refs.span.nodeName).toBe('SPAN');
-            layerMounted = true;
-          },
-        );
-      }
-      componentWillUnmount() {
-        ReactDOMStack.unmountComponentAtNode(this._container);
-      }
-    }
-    const container = document.createElement('div');
-    const a = ReactDOMFiber.render(<A />, container);
-    expect(a.refs.span).toBeTruthy();
-    ReactDOMFiber.unmountComponentAtNode(container);
-    expect(a.refs.span).toBe(undefined);
-    expect(layerMounted).toBe(true);
-  });
-
-  it('attaches, detaches from stack component with fiber layer', () => {
-    const ReactCurrentOwner = require('ReactCurrentOwner');
-    const ReactDOM = require('ReactDOMStackEntry');
-    const ReactDOMFiber = require('ReactDOMFiberEntry');
-    const ReactInstanceMap = require('ReactInstanceMap');
-    let layerMounted = false;
-    class A extends React.Component {
-      render() {
-        return <div />;
-      }
-      componentDidMount() {
-        // ReactLayeredComponentMixin sets ReactCurrentOwner manually
-        ReactCurrentOwner.current = ReactInstanceMap.get(this);
-        const span = <span ref="span" />;
-        ReactCurrentOwner.current = null;
-
-        ReactDOMFiber.unstable_renderSubtreeIntoContainer(
-          this,
-          span,
-          (this._container = document.createElement('div')),
-          () => {
-            expect(this.refs.span.nodeName).toBe('SPAN');
-            layerMounted = true;
-          },
-        );
-      }
-      componentWillUnmount() {
-        ReactDOMFiber.unmountComponentAtNode(this._container);
-      }
-    }
-    const container = document.createElement('div');
-    const a = ReactDOM.render(<A />, container);
-    expect(a.refs.span).toBeTruthy();
-    ReactDOM.unmountComponentAtNode(container);
-    expect(a.refs.span).toBe(undefined);
-    expect(layerMounted).toBe(true);
-  });
-});
-
 describe('root level refs', () => {
   beforeEach(() => {
     var ReactFeatureFlags = require('ReactFeatureFlags');
@@ -440,40 +354,38 @@ describe('root level refs', () => {
     expect(ref).toHaveBeenCalledTimes(2);
     expect(ref.mock.calls[1][0]).toBe(null);
 
-    if (ReactDOMFeatureFlags.useFiber) {
-      // fragment
-      inst = null;
-      ref = jest.fn(value => (inst = value));
-      var divInst = null;
-      var ref2 = jest.fn(value => (divInst = value));
-      result = ReactDOM.render(
-        [<Comp ref={ref} key="a" />, 5, <div ref={ref2} key="b">Hello</div>],
-        container,
-      );
+    // fragment
+    inst = null;
+    ref = jest.fn(value => (inst = value));
+    var divInst = null;
+    var ref2 = jest.fn(value => (divInst = value));
+    result = ReactDOM.render(
+      [<Comp ref={ref} key="a" />, 5, <div ref={ref2} key="b">Hello</div>],
+      container,
+    );
 
-      // first call should be `Comp`
-      expect(ref).toHaveBeenCalledTimes(1);
-      expect(ref.mock.calls[0][0]).toBeInstanceOf(Comp);
-      expect(result).toBe(ref.mock.calls[0][0]);
+    // first call should be `Comp`
+    expect(ref).toHaveBeenCalledTimes(1);
+    expect(ref.mock.calls[0][0]).toBeInstanceOf(Comp);
+    expect(result).toBe(ref.mock.calls[0][0]);
 
-      expect(ref2).toHaveBeenCalledTimes(1);
-      expect(divInst).toBeInstanceOf(HTMLDivElement);
-      expect(result).not.toBe(divInst);
+    expect(ref2).toHaveBeenCalledTimes(1);
+    expect(divInst).toBeInstanceOf(HTMLDivElement);
+    expect(result).not.toBe(divInst);
 
-      ReactDOM.unmountComponentAtNode(container);
-      expect(ref).toHaveBeenCalledTimes(2);
-      expect(ref.mock.calls[1][0]).toBe(null);
-      expect(ref2).toHaveBeenCalledTimes(2);
-      expect(ref2.mock.calls[1][0]).toBe(null);
+    ReactDOM.unmountComponentAtNode(container);
+    expect(ref).toHaveBeenCalledTimes(2);
+    expect(ref.mock.calls[1][0]).toBe(null);
+    expect(ref2).toHaveBeenCalledTimes(2);
+    expect(ref2.mock.calls[1][0]).toBe(null);
 
-      // null
-      result = ReactDOM.render(null, container);
-      expect(result).toBe(null);
+    // null
+    result = ReactDOM.render(null, container);
+    expect(result).toBe(null);
 
-      // primitives
-      result = ReactDOM.render(5, container);
-      expect(result).toBeInstanceOf(Text);
-    }
+    // primitives
+    result = ReactDOM.render(5, container);
+    expect(result).toBeInstanceOf(Text);
   });
 });
 
@@ -489,28 +401,6 @@ describe('creating element with ref in constructor', () => {
     }
   }
 
-  var devErrorMessage =
-    'addComponentAsRefTo(...): Only a ReactOwner can have refs. You might ' +
-    "be adding a ref to a component that was not created inside a component's " +
-    '`render` method, or you have multiple copies of React loaded ' +
-    '(details: https://fb.me/react-refs-must-have-owner).';
-
-  var prodErrorMessage =
-    'Minified React error #119; visit ' +
-    'http://facebook.github.io/react/docs/error-decoder.html?invariant=119 for the full message ' +
-    'or use the non-minified dev environment for full errors and additional helpful warnings.';
-
-  var fiberDevErrorMessage =
-    'Element ref was specified as a string (p) but no owner was ' +
-    'set. You may have multiple copies of React loaded. ' +
-    '(details: https://fb.me/react-refs-must-have-owner).';
-
-  var fiberProdErrorMessage =
-    'Minified React error #149; visit ' +
-    'http://facebook.github.io/react/docs/error-decoder.html?invariant=149&args[]=p ' +
-    'for the full message or use the non-minified dev environment for full errors and additional ' +
-    'helpful warnings.';
-
   it('throws an error when __DEV__ = true', () => {
     ReactTestUtils = require('react-dom/test-utils');
 
@@ -521,7 +411,9 @@ describe('creating element with ref in constructor', () => {
       expect(function() {
         ReactTestUtils.renderIntoDocument(<RefTest />);
       }).toThrowError(
-        ReactDOMFeatureFlags.useFiber ? fiberDevErrorMessage : devErrorMessage,
+        'Element ref was specified as a string (p) but no owner was ' +
+          'set. You may have multiple copies of React loaded. ' +
+          '(details: https://fb.me/react-refs-must-have-owner).',
       );
     } finally {
       __DEV__ = originalDev;
@@ -538,9 +430,10 @@ describe('creating element with ref in constructor', () => {
       expect(function() {
         ReactTestUtils.renderIntoDocument(<RefTest />);
       }).toThrowError(
-        ReactDOMFeatureFlags.useFiber
-          ? fiberProdErrorMessage
-          : prodErrorMessage,
+        'Minified React error #149; visit ' +
+          'http://facebook.github.io/react/docs/error-decoder.html?invariant=149&args[]=p ' +
+          'for the full message or use the non-minified dev environment for full errors and additional ' +
+          'helpful warnings.',
       );
     } finally {
       __DEV__ = originalDev;
diff --git a/src/renderers/art/ReactARTFiberEntry.js b/src/renderers/art/ReactARTFiberEntry.js
index 0f4086d6fab..db9d5d3d029 100644
--- a/src/renderers/art/ReactARTFiberEntry.js
+++ b/src/renderers/art/ReactARTFiberEntry.js
@@ -10,19 +10,20 @@
  */
 'use strict';
 
-require('art/modes/current').setCurrent(
+import Mode from 'art/modes/current';
+import fastNoSideEffectsMode from 'art/modes/fast-noSideEffects';
+import Transform from 'art/core/transform';
+import invariant from 'fbjs/lib/invariant';
+import emptyObject from 'fbjs/lib/emptyObject';
+import React from 'react';
+import ReactFiberReconciler from 'ReactFiberReconciler';
+import {rIC} from 'ReactDOMFrameScheduling';
+
+Mode.setCurrent(
   // Change to 'art/modes/dom' for easier debugging via SVG
-  require('art/modes/fast-noSideEffects'),
+  fastNoSideEffectsMode,
 );
 
-const Mode = require('art/modes/current');
-const Transform = require('art/core/transform');
-const invariant = require('fbjs/lib/invariant');
-const emptyObject = require('fbjs/lib/emptyObject');
-const React = require('react');
-const ReactFiberReconciler = require('ReactFiberReconciler');
-const ReactDOMFrameScheduling = require('ReactDOMFrameScheduling');
-
 const {Component} = React;
 
 const pooledTransform = new Transform();
@@ -526,7 +527,7 @@ const ARTRenderer = ReactFiberReconciler({
     return emptyObject;
   },
 
-  scheduleDeferredCallback: ReactDOMFrameScheduling.rIC,
+  scheduleDeferredCallback: rIC,
 
   shouldSetTextContent(type, props) {
     return (
@@ -539,7 +540,9 @@ const ARTRenderer = ReactFiberReconciler({
 
 /** API */
 
-module.exports = {
+// TODO: this fixes Rollup build but probably breaks Jest.
+// Need to figure something out.
+export default {
   ClippingRectangle: TYPES.CLIPPING_RECTANGLE,
   Group: TYPES.GROUP,
   LinearGradient,
diff --git a/src/renderers/dom/ReactDOMNodeStreamRenderer.js b/src/renderers/dom/ReactDOMNodeStreamRenderer.js
index 7a54db65317..0e208b9b2c9 100644
--- a/src/renderers/dom/ReactDOMNodeStreamRenderer.js
+++ b/src/renderers/dom/ReactDOMNodeStreamRenderer.js
@@ -11,12 +11,12 @@
 
 'use strict';
 
-var invariant = require('fbjs/lib/invariant');
-var React = require('react');
-var ReactPartialRenderer = require('ReactPartialRenderer');
-var ReactFeatureFlags = require('ReactFeatureFlags');
+import invariant from 'fbjs/lib/invariant';
+import React from 'react';
+import ReactPartialRenderer from 'ReactPartialRenderer';
+import ReactFeatureFlags from 'ReactFeatureFlags';
 
-var Readable = require('stream').Readable;
+import {Readable} from 'stream';
 
 // This is a Readable Node.js stream which wraps the ReactDOMPartialRenderer.
 class ReactMarkupReadableStream extends Readable {
@@ -40,7 +40,7 @@ class ReactMarkupReadableStream extends Readable {
  * server.
  * See https://facebook.github.io/react/docs/react-dom-stream.html#rendertonodestream
  */
-function renderToNodeStream(element) {
+export function renderToNodeStream(element) {
   const disableNewFiberFeatures = ReactFeatureFlags.disableNewFiberFeatures;
   if (disableNewFiberFeatures) {
     invariant(
@@ -56,7 +56,7 @@ function renderToNodeStream(element) {
  * such as data-react-id that React uses internally.
  * See https://facebook.github.io/react/docs/react-dom-stream.html#rendertostaticnodestream
  */
-function renderToStaticNodeStream(element) {
+export function renderToStaticNodeStream(element) {
   const disableNewFiberFeatures = ReactFeatureFlags.disableNewFiberFeatures;
   if (disableNewFiberFeatures) {
     invariant(
@@ -66,8 +66,3 @@ function renderToStaticNodeStream(element) {
   }
   return new ReactMarkupReadableStream(element, true);
 }
-
-module.exports = {
-  renderToNodeStream: renderToNodeStream,
-  renderToStaticNodeStream: renderToStaticNodeStream,
-};
diff --git a/src/renderers/dom/ReactDOMServerBrowserEntry.js b/src/renderers/dom/ReactDOMServerBrowserEntry.js
index 0b1ecfefa3b..6ffef37f415 100644
--- a/src/renderers/dom/ReactDOMServerBrowserEntry.js
+++ b/src/renderers/dom/ReactDOMServerBrowserEntry.js
@@ -11,15 +11,16 @@
 
 'use strict';
 
-var ReactDOMStringRenderer = require('ReactDOMStringRenderer');
-var ReactVersion = require('ReactVersion');
-var invariant = require('fbjs/lib/invariant');
+import 'ReactDOMInjection';
+import {renderToString, renderToStaticMarkup} from 'ReactDOMStringRenderer';
+import ReactVersion from 'ReactVersion';
+import invariant from 'fbjs/lib/invariant';
 
-require('ReactDOMInjection');
-
-module.exports = {
-  renderToString: ReactDOMStringRenderer.renderToString,
-  renderToStaticMarkup: ReactDOMStringRenderer.renderToStaticMarkup,
+// TODO: this fixes Rollup build but probably breaks Jest.
+// Need to figure something out.
+export default {
+  renderToString,
+  renderToStaticMarkup,
   renderToNodeStream() {
     invariant(
       false,
diff --git a/src/renderers/dom/ReactDOMServerNodeEntry.js b/src/renderers/dom/ReactDOMServerNodeEntry.js
index 1996b57ee54..6087b7d9f72 100644
--- a/src/renderers/dom/ReactDOMServerNodeEntry.js
+++ b/src/renderers/dom/ReactDOMServerNodeEntry.js
@@ -11,16 +11,20 @@
 
 'use strict';
 
-var ReactDOMStringRenderer = require('ReactDOMStringRenderer');
-var ReactDOMNodeStreamRenderer = require('ReactDOMNodeStreamRenderer');
-var ReactVersion = require('ReactVersion');
+import 'ReactDOMInjection';
+import {renderToString, renderToStaticMarkup} from 'ReactDOMStringRenderer';
+import {
+  renderToNodeStream,
+  renderToStaticNodeStream,
+} from 'ReactDOMNodeStreamRenderer';
+import ReactVersion from 'ReactVersion';
 
-require('ReactDOMInjection');
-
-module.exports = {
-  renderToString: ReactDOMStringRenderer.renderToString,
-  renderToStaticMarkup: ReactDOMStringRenderer.renderToStaticMarkup,
-  renderToNodeStream: ReactDOMNodeStreamRenderer.renderToNodeStream,
-  renderToStaticNodeStream: ReactDOMNodeStreamRenderer.renderToStaticNodeStream,
+// TODO: this fixes Rollup build but probably breaks Jest.
+// Need to figure something out.
+export default {
+  renderToString,
+  renderToStaticMarkup,
+  renderToNodeStream,
+  renderToStaticNodeStream,
   version: ReactVersion,
 };
diff --git a/src/renderers/dom/ReactDOMServerStackEntry.js b/src/renderers/dom/ReactDOMServerStackEntry.js
deleted file mode 100644
index 67ca724da8f..00000000000
--- a/src/renderers/dom/ReactDOMServerStackEntry.js
+++ /dev/null
@@ -1,37 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMServerStackEntry
- */
-
-'use strict';
-
-var ReactServerRendering = require('ReactServerRendering');
-var ReactVersion = require('ReactVersion');
-
-require('ReactDOMInjection');
-require('ReactDOMStackInjection');
-
-var ReactDOMServerStack = {
-  renderToString: ReactServerRendering.renderToString,
-  renderToStaticMarkup: ReactServerRendering.renderToStaticMarkup,
-  version: ReactVersion,
-};
-
-if (__DEV__) {
-  var ReactInstrumentation = require('ReactInstrumentation');
-  var ReactDOMUnknownPropertyHook = require('ReactDOMUnknownPropertyHook');
-  var ReactDOMNullInputValuePropHook = require('ReactDOMNullInputValuePropHook');
-  var ReactDOMInvalidARIAHook = require('ReactDOMInvalidARIAHook');
-
-  ReactInstrumentation.debugTool.addHook(ReactDOMUnknownPropertyHook);
-  ReactInstrumentation.debugTool.addHook(ReactDOMNullInputValuePropHook);
-  ReactInstrumentation.debugTool.addHook(ReactDOMInvalidARIAHook);
-}
-
-module.exports = ReactDOMServerStack;
diff --git a/src/renderers/dom/ReactDOMStackEntry.js b/src/renderers/dom/ReactDOMStackEntry.js
deleted file mode 100644
index fe12a60eb07..00000000000
--- a/src/renderers/dom/ReactDOMStackEntry.js
+++ /dev/null
@@ -1,170 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMStackEntry
- */
-
-/* globals __REACT_DEVTOOLS_GLOBAL_HOOK__*/
-
-'use strict';
-
-require('checkReact');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactGenericBatching = require('ReactGenericBatching');
-var ReactMount = require('ReactMount');
-var ReactUpdates = require('ReactUpdates');
-var ReactReconciler = require('ReactReconciler');
-var ReactVersion = require('ReactVersion');
-
-var findDOMNode = require('findDOMNode');
-var getHostComponentFromComposite = require('getHostComponentFromComposite');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
-require('ReactDOMInjection');
-require('ReactDOMClientInjection');
-require('ReactDOMStackInjection');
-
-var ReactDOMStack = {
-  findDOMNode: findDOMNode,
-  render: ReactMount.render,
-  unmountComponentAtNode: ReactMount.unmountComponentAtNode,
-  version: ReactVersion,
-
-  /* eslint-disable camelcase */
-  unstable_batchedUpdates: ReactGenericBatching.batchedUpdates,
-  unstable_renderSubtreeIntoContainer: ReactMount.renderSubtreeIntoContainer,
-  /* eslint-enable camelcase */
-
-  __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: {
-    // For TapEventPlugin which is popular in open source
-    EventPluginHub: require('EventPluginHub'),
-    // Used by test-utils
-    EventPluginRegistry: require('EventPluginRegistry'),
-    EventPropagators: require('EventPropagators'),
-    ReactControlledComponent: require('ReactControlledComponent'),
-    ReactDOMComponentTree,
-    ReactDOMEventListener: require('ReactDOMEventListener'),
-    ReactUpdates: ReactUpdates,
-  },
-};
-
-// Inject the runtime into a devtools global hook regardless of browser.
-// Allows for debugging when the hook is injected on the page.
-if (
-  typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ !== 'undefined' &&
-  typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.inject === 'function'
-) {
-  __REACT_DEVTOOLS_GLOBAL_HOOK__.inject({
-    ComponentTree: {
-      getClosestInstanceFromNode: ReactDOMComponentTree.getClosestInstanceFromNode,
-      getNodeFromInstance: function(inst) {
-        // inst is an internal instance (but could be a composite)
-        if (inst._renderedComponent) {
-          inst = getHostComponentFromComposite(inst);
-        }
-        if (inst) {
-          return ReactDOMComponentTree.getNodeFromInstance(inst);
-        } else {
-          return null;
-        }
-      },
-    },
-    Mount: ReactMount,
-    Reconciler: ReactReconciler,
-    rendererPackageName: 'react-dom',
-  });
-}
-
-if (__DEV__) {
-  var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
-  if (ExecutionEnvironment.canUseDOM && window.top === window.self) {
-    // First check if devtools is not installed
-    if (typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ === 'undefined') {
-      // If we're in Chrome or Firefox, provide a download link if not installed.
-      if (
-        (navigator.userAgent.indexOf('Chrome') > -1 &&
-          navigator.userAgent.indexOf('Edge') === -1) ||
-        navigator.userAgent.indexOf('Firefox') > -1
-      ) {
-        // Firefox does not have the issue with devtools loaded over file://
-        var showFileUrlMessage =
-          window.location.protocol.indexOf('http') === -1 &&
-          navigator.userAgent.indexOf('Firefox') === -1;
-        console.debug(
-          'Download the React DevTools ' +
-            (showFileUrlMessage
-              ? 'and use an HTTP server (instead of a file: URL) '
-              : '') +
-            'for a better development experience: ' +
-            'https://fb.me/react-devtools',
-        );
-      }
-    }
-
-    var testFunc = function testFn() {};
-    warning(
-      (testFunc.name || testFunc.toString()).indexOf('testFn') !== -1,
-      "It looks like you're using a minified copy of the development build " +
-        'of React. When deploying React apps to production, make sure to use ' +
-        'the production build which skips development warnings and is faster. ' +
-        'See https://fb.me/react-minification for more details.',
-    );
-
-    // If we're in IE8, check to see if we are in compatibility mode and provide
-    // information on preventing compatibility mode
-    var ieCompatibilityMode =
-      document.documentMode && document.documentMode < 8;
-
-    warning(
-      !ieCompatibilityMode,
-      'Internet Explorer is running in compatibility mode; please add the ' +
-        'following tag to your HTML to prevent this from happening: ' +
-        '<meta http-equiv="X-UA-Compatible" content="IE=edge" />',
-    );
-
-    var expectedFeatures = [
-      // shims
-      Array.isArray,
-      Array.prototype.every,
-      Array.prototype.forEach,
-      Array.prototype.indexOf,
-      Array.prototype.map,
-      Date.now,
-      Function.prototype.bind,
-      Object.keys,
-      String.prototype.trim,
-    ];
-
-    for (var i = 0; i < expectedFeatures.length; i++) {
-      if (!expectedFeatures[i]) {
-        warning(
-          false,
-          'One or more ES5 shims expected by React are not available: ' +
-            'https://fb.me/react-warning-polyfills',
-        );
-        break;
-      }
-    }
-  }
-}
-
-if (__DEV__) {
-  var ReactInstrumentation = require('ReactInstrumentation');
-  var ReactDOMUnknownPropertyHook = require('ReactDOMUnknownPropertyHook');
-  var ReactDOMNullInputValuePropHook = require('ReactDOMNullInputValuePropHook');
-  var ReactDOMInvalidARIAHook = require('ReactDOMInvalidARIAHook');
-
-  ReactInstrumentation.debugTool.addHook(ReactDOMUnknownPropertyHook);
-  ReactInstrumentation.debugTool.addHook(ReactDOMNullInputValuePropHook);
-  ReactInstrumentation.debugTool.addHook(ReactDOMInvalidARIAHook);
-}
-
-module.exports = ReactDOMStack;
diff --git a/src/renderers/dom/ReactDOMStringRenderer.js b/src/renderers/dom/ReactDOMStringRenderer.js
index 4374e29721d..e392ddc69eb 100644
--- a/src/renderers/dom/ReactDOMStringRenderer.js
+++ b/src/renderers/dom/ReactDOMStringRenderer.js
@@ -11,17 +11,17 @@
 
 'use strict';
 
-var invariant = require('fbjs/lib/invariant');
-var React = require('react');
-var ReactPartialRenderer = require('ReactPartialRenderer');
-var ReactFeatureFlags = require('ReactFeatureFlags');
+import invariant from 'fbjs/lib/invariant';
+import React from 'react';
+import ReactPartialRenderer from 'ReactPartialRenderer';
+import ReactFeatureFlags from 'ReactFeatureFlags';
 
 /**
  * Render a ReactElement to its initial HTML. This should only be used on the
  * server.
  * See https://facebook.github.io/react/docs/react-dom-server.html#rendertostring
  */
-function renderToString(element) {
+export function renderToString(element) {
   const disableNewFiberFeatures = ReactFeatureFlags.disableNewFiberFeatures;
   if (disableNewFiberFeatures) {
     invariant(
@@ -39,7 +39,7 @@ function renderToString(element) {
  * such as data-react-id that React uses internally.
  * See https://facebook.github.io/react/docs/react-dom-server.html#rendertostaticmarkup
  */
-function renderToStaticMarkup(element) {
+export function renderToStaticMarkup(element) {
   const disableNewFiberFeatures = ReactFeatureFlags.disableNewFiberFeatures;
   if (disableNewFiberFeatures) {
     invariant(
@@ -51,8 +51,3 @@ function renderToStaticMarkup(element) {
   var markup = renderer.read(Infinity);
   return markup;
 }
-
-module.exports = {
-  renderToString: renderToString,
-  renderToStaticMarkup: renderToStaticMarkup,
-};
diff --git a/src/renderers/dom/__tests__/ReactDOMProduction-test.js b/src/renderers/dom/__tests__/ReactDOMProduction-test.js
index d4fab65a45d..1c33de7dca0 100644
--- a/src/renderers/dom/__tests__/ReactDOMProduction-test.js
+++ b/src/renderers/dom/__tests__/ReactDOMProduction-test.js
@@ -11,8 +11,6 @@
 'use strict';
 
 describe('ReactDOMProduction', () => {
-  var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-
   var React;
   var ReactDOM;
   var ReactDOMServer;
@@ -236,60 +234,58 @@ describe('ReactDOMProduction', () => {
     }
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    // This test is originally from ReactDOMFiber-test but we replicate it here
-    // to avoid production-only regressions because of host context differences
-    // in dev and prod.
-    it('should keep track of namespace across portals in production', () => {
-      var svgEls, htmlEls;
-      var expectSVG = {ref: el => svgEls.push(el)};
-      var expectHTML = {ref: el => htmlEls.push(el)};
-      var usePortal = function(tree) {
-        return ReactDOM.unstable_createPortal(
-          tree,
-          document.createElement('div'),
-        );
-      };
-      var assertNamespacesMatch = function(tree) {
-        var container = document.createElement('div');
-        svgEls = [];
-        htmlEls = [];
-        ReactDOM.render(tree, container);
-        svgEls.forEach(el => {
-          expect(el.namespaceURI).toBe('http://www.w3.org/2000/svg');
-        });
-        htmlEls.forEach(el => {
-          expect(el.namespaceURI).toBe('http://www.w3.org/1999/xhtml');
-        });
-        ReactDOM.unmountComponentAtNode(container);
-        expect(container.innerHTML).toBe('');
-      };
+  // This test is originally from ReactDOMFiber-test but we replicate it here
+  // to avoid production-only regressions because of host context differences
+  // in dev and prod.
+  it('should keep track of namespace across portals in production', () => {
+    var svgEls, htmlEls;
+    var expectSVG = {ref: el => svgEls.push(el)};
+    var expectHTML = {ref: el => htmlEls.push(el)};
+    var usePortal = function(tree) {
+      return ReactDOM.unstable_createPortal(
+        tree,
+        document.createElement('div'),
+      );
+    };
+    var assertNamespacesMatch = function(tree) {
+      var container = document.createElement('div');
+      svgEls = [];
+      htmlEls = [];
+      ReactDOM.render(tree, container);
+      svgEls.forEach(el => {
+        expect(el.namespaceURI).toBe('http://www.w3.org/2000/svg');
+      });
+      htmlEls.forEach(el => {
+        expect(el.namespaceURI).toBe('http://www.w3.org/1999/xhtml');
+      });
+      ReactDOM.unmountComponentAtNode(container);
+      expect(container.innerHTML).toBe('');
+    };
 
-      assertNamespacesMatch(
-        <div {...expectHTML}>
-          <svg {...expectSVG}>
-            <foreignObject {...expectSVG}>
-              <p {...expectHTML} />
-              {usePortal(
+    assertNamespacesMatch(
+      <div {...expectHTML}>
+        <svg {...expectSVG}>
+          <foreignObject {...expectSVG}>
+            <p {...expectHTML} />
+            {usePortal(
+              <svg {...expectSVG}>
+                <image {...expectSVG} />
                 <svg {...expectSVG}>
                   <image {...expectSVG} />
-                  <svg {...expectSVG}>
-                    <image {...expectSVG} />
-                    <foreignObject {...expectSVG}>
-                      <p {...expectHTML} />
-                    </foreignObject>
-                    {usePortal(<p {...expectHTML} />)}
-                  </svg>
-                  <image {...expectSVG} />
-                </svg>,
-              )}
-              <p {...expectHTML} />
-            </foreignObject>
-            <image {...expectSVG} />
-          </svg>
-          <p {...expectHTML} />
-        </div>,
-      );
-    });
-  }
+                  <foreignObject {...expectSVG}>
+                    <p {...expectHTML} />
+                  </foreignObject>
+                  {usePortal(<p {...expectHTML} />)}
+                </svg>
+                <image {...expectSVG} />
+              </svg>,
+            )}
+            <p {...expectHTML} />
+          </foreignObject>
+          <image {...expectSVG} />
+        </svg>
+        <p {...expectHTML} />
+      </div>,
+    );
+  });
 });
diff --git a/src/renderers/dom/fiber/ReactDOMFiberComponent.js b/src/renderers/dom/fiber/ReactDOMFiberComponent.js
index 475960cdf7e..f9c685f860e 100644
--- a/src/renderers/dom/fiber/ReactDOMFiberComponent.js
+++ b/src/renderers/dom/fiber/ReactDOMFiberComponent.js
@@ -12,55 +12,82 @@
 
 'use strict';
 
-var CSSPropertyOperations = require('CSSPropertyOperations');
-var DOMNamespaces = require('DOMNamespaces');
-var DOMProperty = require('DOMProperty');
-var DOMPropertyOperations = require('DOMPropertyOperations');
-var EventPluginRegistry = require('EventPluginRegistry');
-var ReactBrowserEventEmitter = require('ReactBrowserEventEmitter');
-var ReactDOMFiberInput = require('ReactDOMFiberInput');
-var ReactDOMFiberOption = require('ReactDOMFiberOption');
-var ReactDOMFiberSelect = require('ReactDOMFiberSelect');
-var ReactDOMFiberTextarea = require('ReactDOMFiberTextarea');
-var {getCurrentFiberOwnerName} = require('ReactDebugCurrentFiber');
-var {DOCUMENT_NODE, DOCUMENT_FRAGMENT_NODE} = require('HTMLNodeType');
+import {
+  setValueForStyles,
+  createDangerousStringForStyles,
+} from 'CSSPropertyOperations';
+import {Namespaces, getIntrinsicNamespace} from 'DOMNamespaces';
+import {shouldSetAttribute, getPropertyInfo} from 'DOMProperty';
+import {
+  deleteValueForAttribute,
+  deleteValueForProperty,
+  getValueForAttribute,
+  getValueForProperty,
+  setValueForAttribute,
+  setValueForProperty,
+} from 'DOMPropertyOperations';
+import {registrationNameModules} from 'EventPluginRegistry';
+import {listenTo, trapBubbledEvent} from 'ReactBrowserEventEmitter';
+import {
+  getHostProps as getHostPropsForInput,
+  initWrapperState as initWrapperStateForInput,
+  postMountWrapper as postMountWrapperForInput,
+  restoreControlledState as restoreControlledStateForInput,
+  updateWrapper as updateWrapperForInput,
+} from 'ReactDOMFiberInput';
+import {
+  getHostProps as getHostPropsForOption,
+  postMountWrapper as postMountWrapperForOption,
+  validateProps as validatePropsForOption,
+} from 'ReactDOMFiberOption';
+import {
+  getHostProps as getHostPropsForSelect,
+  initWrapperState as initWrapperStateForSelect,
+  postMountWrapper as postMountWrapperForSelect,
+  postUpdateWrapper as postUpdateWrapperForSelect,
+  restoreControlledState as restoreControlledStateForSelect,
+} from 'ReactDOMFiberSelect';
+import {
+  initWrapperState as initWrapperStateForTextarea,
+  getHostProps as getHostPropsForTextarea,
+  postMountWrapper as postMountWrapperForTextarea,
+  restoreControlledState as restoreControlledStateForTextarea,
+  updateWrapper as updateWrapperForTextarea,
+} from 'ReactDOMFiberTextarea';
+import {getCurrentFiberOwnerName} from 'ReactDebugCurrentFiber';
+import {DOCUMENT_NODE, DOCUMENT_FRAGMENT_NODE} from 'HTMLNodeType';
+import assertValidProps from 'assertValidProps';
+import emptyFunction from 'fbjs/lib/emptyFunction';
+import {
+  track as trackInputValue,
+  updateValueIfChanged as updateInputValueIfChanged,
+} from 'inputValueTracking';
+import isCustomComponent from 'isCustomComponent';
+import setInnerHTML from 'setInnerHTML';
+import setTextContent from 'setTextContent';
+import warning from 'fbjs/lib/warning';
+import {
+  validateProperties as validateARIAProperties,
+} from 'ReactDOMInvalidARIAHook';
+import {
+  validateProperties as validateInputPropertes,
+} from 'ReactDOMNullInputValuePropHook';
+import {
+  validateProperties as validateUnknownPropertes,
+} from 'ReactDOMUnknownPropertyHook';
+import {getCurrentFiberStackAddendum} from 'ReactDebugCurrentFiber';
 
-var assertValidProps = require('assertValidProps');
-var emptyFunction = require('fbjs/lib/emptyFunction');
-var inputValueTracking = require('inputValueTracking');
-var isCustomComponent = require('isCustomComponent');
-var setInnerHTML = require('setInnerHTML');
-var setTextContent = require('setTextContent');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var {getCurrentFiberStackAddendum} = require('ReactDebugCurrentFiber');
-  var ReactDOMInvalidARIAHook = require('ReactDOMInvalidARIAHook');
-  var ReactDOMNullInputValuePropHook = require('ReactDOMNullInputValuePropHook');
-  var ReactDOMUnknownPropertyHook = require('ReactDOMUnknownPropertyHook');
-  var {validateProperties: validateARIAProperties} = ReactDOMInvalidARIAHook;
-  var {
-    validateProperties: validateInputPropertes,
-  } = ReactDOMNullInputValuePropHook;
-  var {
-    validateProperties: validateUnknownPropertes,
-  } = ReactDOMUnknownPropertyHook;
-}
+var {html: HTML_NAMESPACE} = Namespaces;
 
 var didWarnInvalidHydration = false;
 var didWarnShadyDOM = false;
 
-var listenTo = ReactBrowserEventEmitter.listenTo;
-var registrationNameModules = EventPluginRegistry.registrationNameModules;
-
 var DANGEROUSLY_SET_INNER_HTML = 'dangerouslySetInnerHTML';
 var SUPPRESS_CONTENT_EDITABLE_WARNING = 'suppressContentEditableWarning';
 var CHILDREN = 'children';
 var STYLE = 'style';
 var HTML = '__html';
 
-var {Namespaces: {html: HTML_NAMESPACE}, getIntrinsicNamespace} = DOMNamespaces;
-
 if (__DEV__) {
   var warnedUnknownTags = {
     // Chrome is the only major browser not shipping <time>. But as of July
@@ -218,7 +245,7 @@ function setInitialDOMProperties(
         }
       }
       // Relies on `updateStylesByID` not mutating `styleUpdates`.
-      CSSPropertyOperations.setValueForStyles(domElement, nextProp);
+      setValueForStyles(domElement, nextProp);
     } else if (propKey === DANGEROUSLY_SET_INNER_HTML) {
       var nextHtml = nextProp ? nextProp[HTML] : undefined;
       if (nextHtml != null) {
@@ -233,19 +260,19 @@ function setInitialDOMProperties(
     } else if (propKey === SUPPRESS_CONTENT_EDITABLE_WARNING) {
       // Noop
     } else if (registrationNameModules.hasOwnProperty(propKey)) {
+      if (__DEV__ && typeof nextProp !== 'function') {
+        warnForInvalidEventListener(propKey, nextProp);
+      }
       if (nextProp) {
-        if (__DEV__ && typeof nextProp !== 'function') {
-          warnForInvalidEventListener(propKey, nextProp);
-        }
         ensureListeningTo(rootContainerElement, propKey);
       }
     } else if (isCustomComponentTag) {
-      DOMPropertyOperations.setValueForAttribute(domElement, propKey, nextProp);
+      setValueForAttribute(domElement, propKey, nextProp);
     } else if (nextProp != null) {
       // If we're updating to null or undefined, we should remove the property
       // from the DOM node instead of inadvertently setting to a string. This
       // brings us in line with the same behavior we have on initial render.
-      DOMPropertyOperations.setValueForProperty(domElement, propKey, nextProp);
+      setValueForProperty(domElement, propKey, nextProp);
     }
   }
 }
@@ -261,911 +288,797 @@ function updateDOMProperties(
     var propKey = updatePayload[i];
     var propValue = updatePayload[i + 1];
     if (propKey === STYLE) {
-      CSSPropertyOperations.setValueForStyles(domElement, propValue);
+      setValueForStyles(domElement, propValue);
     } else if (propKey === DANGEROUSLY_SET_INNER_HTML) {
       setInnerHTML(domElement, propValue);
     } else if (propKey === CHILDREN) {
       setTextContent(domElement, propValue);
     } else if (isCustomComponentTag) {
       if (propValue != null) {
-        DOMPropertyOperations.setValueForAttribute(
-          domElement,
-          propKey,
-          propValue,
-        );
+        setValueForAttribute(domElement, propKey, propValue);
       } else {
-        DOMPropertyOperations.deleteValueForAttribute(domElement, propKey);
+        deleteValueForAttribute(domElement, propKey);
       }
     } else if (propValue != null) {
-      DOMPropertyOperations.setValueForProperty(domElement, propKey, propValue);
+      setValueForProperty(domElement, propKey, propValue);
     } else {
       // If we're updating to null or undefined, we should remove the property
       // from the DOM node instead of inadvertently setting to a string. This
       // brings us in line with the same behavior we have on initial render.
-      DOMPropertyOperations.deleteValueForProperty(domElement, propKey);
+      deleteValueForProperty(domElement, propKey);
     }
   }
 }
 
-var ReactDOMFiberComponent = {
-  createElement(
-    type: *,
-    props: Object,
-    rootContainerElement: Element | Document,
-    parentNamespace: string,
-  ): Element {
-    // We create tags in the namespace of their parent container, except HTML
-    // tags get no namespace.
-    var ownerDocument: Document = rootContainerElement.nodeType ===
-      DOCUMENT_NODE
-      ? (rootContainerElement: any)
-      : rootContainerElement.ownerDocument;
-    var domElement: Element;
-    var namespaceURI = parentNamespace;
-    if (namespaceURI === HTML_NAMESPACE) {
-      namespaceURI = getIntrinsicNamespace(type);
-    }
+export function createElement(
+  type: *,
+  props: Object,
+  rootContainerElement: Element | Document,
+  parentNamespace: string,
+): Element {
+  // We create tags in the namespace of their parent container, except HTML
+  // tags get no namespace.
+  var ownerDocument: Document = rootContainerElement.nodeType === DOCUMENT_NODE
+    ? (rootContainerElement: any)
+    : rootContainerElement.ownerDocument;
+  var domElement: Element;
+  var namespaceURI = parentNamespace;
+  if (namespaceURI === HTML_NAMESPACE) {
+    namespaceURI = getIntrinsicNamespace(type);
+  }
+  if (__DEV__) {
+    var isCustomComponentTag = isCustomComponent(type, props);
+  }
+  if (namespaceURI === HTML_NAMESPACE) {
     if (__DEV__) {
-      var isCustomComponentTag = isCustomComponent(type, props);
+      // Should this check be gated by parent namespace? Not sure we want to
+      // allow <SVG> or <mATH>.
+      warning(
+        isCustomComponentTag || type === type.toLowerCase(),
+        '<%s /> is using uppercase HTML. Always use lowercase HTML tags ' +
+          'in React.',
+        type,
+      );
     }
-    if (namespaceURI === HTML_NAMESPACE) {
-      if (__DEV__) {
-        // Should this check be gated by parent namespace? Not sure we want to
-        // allow <SVG> or <mATH>.
-        warning(
-          isCustomComponentTag || type === type.toLowerCase(),
-          '<%s /> is using uppercase HTML. Always use lowercase HTML tags ' +
-            'in React.',
-          type,
-        );
-      }
 
-      if (type === 'script') {
-        // Create the script via .innerHTML so its "parser-inserted" flag is
-        // set to true and it does not execute
-        var div = ownerDocument.createElement('div');
-        div.innerHTML = '<script><' + '/script>'; // eslint-disable-line
-        // This is guaranteed to yield a script element.
-        var firstChild = ((div.firstChild: any): HTMLScriptElement);
-        domElement = div.removeChild(firstChild);
-      } else if (props.is) {
-        // $FlowIssue `createElement` should be updated for Web Components
-        domElement = ownerDocument.createElement(type, {is: props.is});
-      } else {
-        // Separate else branch instead of using `props.is || undefined` above because of a Firefox bug.
-        // See discussion in https://github.com/facebook/react/pull/6896
-        // and discussion in https://bugzilla.mozilla.org/show_bug.cgi?id=1276240
-        domElement = ownerDocument.createElement(type);
-      }
+    if (type === 'script') {
+      // Create the script via .innerHTML so its "parser-inserted" flag is
+      // set to true and it does not execute
+      var div = ownerDocument.createElement('div');
+      div.innerHTML = '<script><' + '/script>'; // eslint-disable-line
+      // This is guaranteed to yield a script element.
+      var firstChild = ((div.firstChild: any): HTMLScriptElement);
+      domElement = div.removeChild(firstChild);
+    } else if (props.is) {
+      // $FlowIssue `createElement` should be updated for Web Components
+      domElement = ownerDocument.createElement(type, {is: props.is});
     } else {
-      domElement = ownerDocument.createElementNS(namespaceURI, type);
-    }
-
-    if (__DEV__) {
-      if (namespaceURI === HTML_NAMESPACE) {
-        if (
-          !isCustomComponentTag &&
-          Object.prototype.toString.call(domElement) ===
-            '[object HTMLUnknownElement]' &&
-          !Object.prototype.hasOwnProperty.call(warnedUnknownTags, type)
-        ) {
-          warnedUnknownTags[type] = true;
-          warning(
-            false,
-            'The tag <%s> is unrecognized in this browser. ' +
-              'If you meant to render a React component, start its name with ' +
-              'an uppercase letter.',
-            type,
-          );
-        }
-      }
+      // Separate else branch instead of using `props.is || undefined` above because of a Firefox bug.
+      // See discussion in https://github.com/facebook/react/pull/6896
+      // and discussion in https://bugzilla.mozilla.org/show_bug.cgi?id=1276240
+      domElement = ownerDocument.createElement(type);
     }
+  } else {
+    domElement = ownerDocument.createElementNS(namespaceURI, type);
+  }
 
-    return domElement;
-  },
-
-  setInitialProperties(
-    domElement: Element,
-    tag: string,
-    rawProps: Object,
-    rootContainerElement: Element | Document,
-  ): void {
-    var isCustomComponentTag = isCustomComponent(tag, rawProps);
-    if (__DEV__) {
-      validatePropertiesInDevelopment(tag, rawProps);
-      if (isCustomComponentTag && !didWarnShadyDOM && domElement.shadyRoot) {
+  if (__DEV__) {
+    if (namespaceURI === HTML_NAMESPACE) {
+      if (
+        !isCustomComponentTag &&
+        Object.prototype.toString.call(domElement) ===
+          '[object HTMLUnknownElement]' &&
+        !Object.prototype.hasOwnProperty.call(warnedUnknownTags, type)
+      ) {
+        warnedUnknownTags[type] = true;
         warning(
           false,
-          '%s is using shady DOM. Using shady DOM with React can ' +
-            'cause things to break subtly.',
-          getCurrentFiberOwnerName() || 'A component',
+          'The tag <%s> is unrecognized in this browser. ' +
+            'If you meant to render a React component, start its name with ' +
+            'an uppercase letter.',
+          type,
         );
-        didWarnShadyDOM = true;
       }
     }
+  }
 
-    // TODO: Make sure that we check isMounted before firing any of these events.
-    var props: Object;
-    switch (tag) {
-      case 'iframe':
-      case 'object':
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topLoad',
-          'load',
-          domElement,
-        );
-        props = rawProps;
-        break;
-      case 'video':
-      case 'audio':
-        // Create listener for each media event
-        for (var event in mediaEvents) {
-          if (mediaEvents.hasOwnProperty(event)) {
-            ReactBrowserEventEmitter.trapBubbledEvent(
-              event,
-              mediaEvents[event],
-              domElement,
-            );
-          }
-        }
-        props = rawProps;
-        break;
-      case 'source':
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topError',
-          'error',
-          domElement,
-        );
-        props = rawProps;
-        break;
-      case 'img':
-      case 'image':
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topError',
-          'error',
-          domElement,
-        );
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topLoad',
-          'load',
-          domElement,
-        );
-        props = rawProps;
-        break;
-      case 'form':
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topReset',
-          'reset',
-          domElement,
-        );
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topSubmit',
-          'submit',
-          domElement,
-        );
-        props = rawProps;
-        break;
-      case 'details':
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topToggle',
-          'toggle',
-          domElement,
-        );
-        props = rawProps;
-        break;
-      case 'input':
-        ReactDOMFiberInput.initWrapperState(domElement, rawProps);
-        props = ReactDOMFiberInput.getHostProps(domElement, rawProps);
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topInvalid',
-          'invalid',
-          domElement,
-        );
-        // For controlled components we always need to ensure we're listening
-        // to onChange. Even if there is no listener.
-        ensureListeningTo(rootContainerElement, 'onChange');
-        break;
-      case 'option':
-        ReactDOMFiberOption.validateProps(domElement, rawProps);
-        props = ReactDOMFiberOption.getHostProps(domElement, rawProps);
-        break;
-      case 'select':
-        ReactDOMFiberSelect.initWrapperState(domElement, rawProps);
-        props = ReactDOMFiberSelect.getHostProps(domElement, rawProps);
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topInvalid',
-          'invalid',
-          domElement,
-        );
-        // For controlled components we always need to ensure we're listening
-        // to onChange. Even if there is no listener.
-        ensureListeningTo(rootContainerElement, 'onChange');
-        break;
-      case 'textarea':
-        ReactDOMFiberTextarea.initWrapperState(domElement, rawProps);
-        props = ReactDOMFiberTextarea.getHostProps(domElement, rawProps);
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topInvalid',
-          'invalid',
-          domElement,
-        );
-        // For controlled components we always need to ensure we're listening
-        // to onChange. Even if there is no listener.
-        ensureListeningTo(rootContainerElement, 'onChange');
-        break;
-      default:
-        props = rawProps;
-    }
-
-    assertValidProps(tag, props, getCurrentFiberOwnerName);
+  return domElement;
+}
 
-    setInitialDOMProperties(
-      domElement,
-      rootContainerElement,
-      props,
-      isCustomComponentTag,
-    );
+export function setInitialProperties(
+  domElement: Element,
+  tag: string,
+  rawProps: Object,
+  rootContainerElement: Element | Document,
+): void {
+  var isCustomComponentTag = isCustomComponent(tag, rawProps);
+  if (__DEV__) {
+    validatePropertiesInDevelopment(tag, rawProps);
+    if (isCustomComponentTag && !didWarnShadyDOM && domElement.shadyRoot) {
+      warning(
+        false,
+        '%s is using shady DOM. Using shady DOM with React can ' +
+          'cause things to break subtly.',
+        getCurrentFiberOwnerName() || 'A component',
+      );
+      didWarnShadyDOM = true;
+    }
+  }
 
-    switch (tag) {
-      case 'input':
-        // TODO: Make sure we check if this is still unmounted or do any clean
-        // up necessary since we never stop tracking anymore.
-        inputValueTracking.track((domElement: any));
-        ReactDOMFiberInput.postMountWrapper(domElement, rawProps);
-        break;
-      case 'textarea':
-        // TODO: Make sure we check if this is still unmounted or do any clean
-        // up necessary since we never stop tracking anymore.
-        inputValueTracking.track((domElement: any));
-        ReactDOMFiberTextarea.postMountWrapper(domElement, rawProps);
-        break;
-      case 'option':
-        ReactDOMFiberOption.postMountWrapper(domElement, rawProps);
-        break;
-      case 'select':
-        ReactDOMFiberSelect.postMountWrapper(domElement, rawProps);
-        break;
-      default:
-        if (typeof props.onClick === 'function') {
-          // TODO: This cast may not be sound for SVG, MathML or custom elements.
-          trapClickOnNonInteractiveElement(((domElement: any): HTMLElement));
+  // TODO: Make sure that we check isMounted before firing any of these events.
+  var props: Object;
+  switch (tag) {
+    case 'iframe':
+    case 'object':
+      trapBubbledEvent('topLoad', 'load', domElement);
+      props = rawProps;
+      break;
+    case 'video':
+    case 'audio':
+      // Create listener for each media event
+      for (var event in mediaEvents) {
+        if (mediaEvents.hasOwnProperty(event)) {
+          trapBubbledEvent(event, mediaEvents[event], domElement);
         }
-        break;
-    }
-  },
+      }
+      props = rawProps;
+      break;
+    case 'source':
+      trapBubbledEvent('topError', 'error', domElement);
+      props = rawProps;
+      break;
+    case 'img':
+    case 'image':
+      trapBubbledEvent('topError', 'error', domElement);
+      trapBubbledEvent('topLoad', 'load', domElement);
+      props = rawProps;
+      break;
+    case 'form':
+      trapBubbledEvent('topReset', 'reset', domElement);
+      trapBubbledEvent('topSubmit', 'submit', domElement);
+      props = rawProps;
+      break;
+    case 'details':
+      trapBubbledEvent('topToggle', 'toggle', domElement);
+      props = rawProps;
+      break;
+    case 'input':
+      initWrapperStateForInput(domElement, rawProps);
+      props = getHostPropsForInput(domElement, rawProps);
+      trapBubbledEvent('topInvalid', 'invalid', domElement);
+      // For controlled components we always need to ensure we're listening
+      // to onChange. Even if there is no listener.
+      ensureListeningTo(rootContainerElement, 'onChange');
+      break;
+    case 'option':
+      validatePropsForOption(domElement, rawProps);
+      props = getHostPropsForOption(domElement, rawProps);
+      break;
+    case 'select':
+      initWrapperStateForSelect(domElement, rawProps);
+      props = getHostPropsForSelect(domElement, rawProps);
+      trapBubbledEvent('topInvalid', 'invalid', domElement);
+      // For controlled components we always need to ensure we're listening
+      // to onChange. Even if there is no listener.
+      ensureListeningTo(rootContainerElement, 'onChange');
+      break;
+    case 'textarea':
+      initWrapperStateForTextarea(domElement, rawProps);
+      props = getHostPropsForTextarea(domElement, rawProps);
+      trapBubbledEvent('topInvalid', 'invalid', domElement);
+      // For controlled components we always need to ensure we're listening
+      // to onChange. Even if there is no listener.
+      ensureListeningTo(rootContainerElement, 'onChange');
+      break;
+    default:
+      props = rawProps;
+  }
 
-  // Calculate the diff between the two objects.
-  diffProperties(
-    domElement: Element,
-    tag: string,
-    lastRawProps: Object,
-    nextRawProps: Object,
-    rootContainerElement: Element | Document,
-  ): null | Array<mixed> {
-    if (__DEV__) {
-      validatePropertiesInDevelopment(tag, nextRawProps);
-    }
+  assertValidProps(tag, props, getCurrentFiberOwnerName);
 
-    var updatePayload: null | Array<any> = null;
+  setInitialDOMProperties(
+    domElement,
+    rootContainerElement,
+    props,
+    isCustomComponentTag,
+  );
 
-    var lastProps: Object;
-    var nextProps: Object;
-    switch (tag) {
-      case 'input':
-        lastProps = ReactDOMFiberInput.getHostProps(domElement, lastRawProps);
-        nextProps = ReactDOMFiberInput.getHostProps(domElement, nextRawProps);
-        updatePayload = [];
-        break;
-      case 'option':
-        lastProps = ReactDOMFiberOption.getHostProps(domElement, lastRawProps);
-        nextProps = ReactDOMFiberOption.getHostProps(domElement, nextRawProps);
-        updatePayload = [];
-        break;
-      case 'select':
-        lastProps = ReactDOMFiberSelect.getHostProps(domElement, lastRawProps);
-        nextProps = ReactDOMFiberSelect.getHostProps(domElement, nextRawProps);
-        updatePayload = [];
-        break;
-      case 'textarea':
-        lastProps = ReactDOMFiberTextarea.getHostProps(
-          domElement,
-          lastRawProps,
-        );
-        nextProps = ReactDOMFiberTextarea.getHostProps(
-          domElement,
-          nextRawProps,
-        );
-        updatePayload = [];
-        break;
-      default:
-        lastProps = lastRawProps;
-        nextProps = nextRawProps;
-        if (
-          typeof lastProps.onClick !== 'function' &&
-          typeof nextProps.onClick === 'function'
-        ) {
-          // TODO: This cast may not be sound for SVG, MathML or custom elements.
-          trapClickOnNonInteractiveElement(((domElement: any): HTMLElement));
-        }
-        break;
-    }
+  switch (tag) {
+    case 'input':
+      // TODO: Make sure we check if this is still unmounted or do any clean
+      // up necessary since we never stop tracking anymore.
+      trackInputValue((domElement: any));
+      postMountWrapperForInput(domElement, rawProps);
+      break;
+    case 'textarea':
+      // TODO: Make sure we check if this is still unmounted or do any clean
+      // up necessary since we never stop tracking anymore.
+      trackInputValue((domElement: any));
+      postMountWrapperForTextarea(domElement, rawProps);
+      break;
+    case 'option':
+      postMountWrapperForOption(domElement, rawProps);
+      break;
+    case 'select':
+      postMountWrapperForSelect(domElement, rawProps);
+      break;
+    default:
+      if (typeof props.onClick === 'function') {
+        // TODO: This cast may not be sound for SVG, MathML or custom elements.
+        trapClickOnNonInteractiveElement(((domElement: any): HTMLElement));
+      }
+      break;
+  }
+}
+
+// Calculate the diff between the two objects.
+export function diffProperties(
+  domElement: Element,
+  tag: string,
+  lastRawProps: Object,
+  nextRawProps: Object,
+  rootContainerElement: Element | Document,
+): null | Array<mixed> {
+  if (__DEV__) {
+    validatePropertiesInDevelopment(tag, nextRawProps);
+  }
 
-    assertValidProps(tag, nextProps, getCurrentFiberOwnerName);
+  var updatePayload: null | Array<any> = null;
 
-    var propKey;
-    var styleName;
-    var styleUpdates = null;
-    for (propKey in lastProps) {
+  var lastProps: Object;
+  var nextProps: Object;
+  switch (tag) {
+    case 'input':
+      lastProps = getHostPropsForInput(domElement, lastRawProps);
+      nextProps = getHostPropsForInput(domElement, nextRawProps);
+      updatePayload = [];
+      break;
+    case 'option':
+      lastProps = getHostPropsForOption(domElement, lastRawProps);
+      nextProps = getHostPropsForOption(domElement, nextRawProps);
+      updatePayload = [];
+      break;
+    case 'select':
+      lastProps = getHostPropsForSelect(domElement, lastRawProps);
+      nextProps = getHostPropsForSelect(domElement, nextRawProps);
+      updatePayload = [];
+      break;
+    case 'textarea':
+      lastProps = getHostPropsForTextarea(domElement, lastRawProps);
+      nextProps = getHostPropsForTextarea(domElement, nextRawProps);
+      updatePayload = [];
+      break;
+    default:
+      lastProps = lastRawProps;
+      nextProps = nextRawProps;
       if (
-        nextProps.hasOwnProperty(propKey) ||
-        !lastProps.hasOwnProperty(propKey) ||
-        lastProps[propKey] == null
+        typeof lastProps.onClick !== 'function' &&
+        typeof nextProps.onClick === 'function'
       ) {
-        continue;
+        // TODO: This cast may not be sound for SVG, MathML or custom elements.
+        trapClickOnNonInteractiveElement(((domElement: any): HTMLElement));
       }
-      if (propKey === STYLE) {
-        var lastStyle = lastProps[propKey];
-        for (styleName in lastStyle) {
-          if (lastStyle.hasOwnProperty(styleName)) {
-            if (!styleUpdates) {
-              styleUpdates = {};
-            }
-            styleUpdates[styleName] = '';
+      break;
+  }
+
+  assertValidProps(tag, nextProps, getCurrentFiberOwnerName);
+
+  var propKey;
+  var styleName;
+  var styleUpdates = null;
+  for (propKey in lastProps) {
+    if (
+      nextProps.hasOwnProperty(propKey) ||
+      !lastProps.hasOwnProperty(propKey) ||
+      lastProps[propKey] == null
+    ) {
+      continue;
+    }
+    if (propKey === STYLE) {
+      var lastStyle = lastProps[propKey];
+      for (styleName in lastStyle) {
+        if (lastStyle.hasOwnProperty(styleName)) {
+          if (!styleUpdates) {
+            styleUpdates = {};
           }
+          styleUpdates[styleName] = '';
         }
-      } else if (
-        propKey === DANGEROUSLY_SET_INNER_HTML ||
-        propKey === CHILDREN
-      ) {
-        // Noop. This is handled by the clear text mechanism.
-      } else if (propKey === SUPPRESS_CONTENT_EDITABLE_WARNING) {
-        // Noop
-      } else if (registrationNameModules.hasOwnProperty(propKey)) {
-        // This is a special case. If any listener updates we need to ensure
-        // that the "current" fiber pointer gets updated so we need a commit
-        // to update this element.
-        if (!updatePayload) {
-          updatePayload = [];
-        }
-      } else {
-        // For all other deleted properties we add it to the queue. We use
-        // the whitelist in the commit phase instead.
-        (updatePayload = updatePayload || []).push(propKey, null);
       }
-    }
-    for (propKey in nextProps) {
-      var nextProp = nextProps[propKey];
-      var lastProp = lastProps != null ? lastProps[propKey] : undefined;
-      if (
-        !nextProps.hasOwnProperty(propKey) ||
-        nextProp === lastProp ||
-        (nextProp == null && lastProp == null)
-      ) {
-        continue;
+    } else if (propKey === DANGEROUSLY_SET_INNER_HTML || propKey === CHILDREN) {
+      // Noop. This is handled by the clear text mechanism.
+    } else if (propKey === SUPPRESS_CONTENT_EDITABLE_WARNING) {
+      // Noop
+    } else if (registrationNameModules.hasOwnProperty(propKey)) {
+      // This is a special case. If any listener updates we need to ensure
+      // that the "current" fiber pointer gets updated so we need a commit
+      // to update this element.
+      if (!updatePayload) {
+        updatePayload = [];
       }
-      if (propKey === STYLE) {
-        if (__DEV__) {
-          if (nextProp) {
-            // Freeze the next style object so that we can assume it won't be
-            // mutated. We have already warned for this in the past.
-            Object.freeze(nextProp);
-          }
+    } else {
+      // For all other deleted properties we add it to the queue. We use
+      // the whitelist in the commit phase instead.
+      (updatePayload = updatePayload || []).push(propKey, null);
+    }
+  }
+  for (propKey in nextProps) {
+    var nextProp = nextProps[propKey];
+    var lastProp = lastProps != null ? lastProps[propKey] : undefined;
+    if (
+      !nextProps.hasOwnProperty(propKey) ||
+      nextProp === lastProp ||
+      (nextProp == null && lastProp == null)
+    ) {
+      continue;
+    }
+    if (propKey === STYLE) {
+      if (__DEV__) {
+        if (nextProp) {
+          // Freeze the next style object so that we can assume it won't be
+          // mutated. We have already warned for this in the past.
+          Object.freeze(nextProp);
         }
-        if (lastProp) {
-          // Unset styles on `lastProp` but not on `nextProp`.
-          for (styleName in lastProp) {
-            if (
-              lastProp.hasOwnProperty(styleName) &&
-              (!nextProp || !nextProp.hasOwnProperty(styleName))
-            ) {
-              if (!styleUpdates) {
-                styleUpdates = {};
-              }
-              styleUpdates[styleName] = '';
-            }
-          }
-          // Update styles that changed since `lastProp`.
-          for (styleName in nextProp) {
-            if (
-              nextProp.hasOwnProperty(styleName) &&
-              lastProp[styleName] !== nextProp[styleName]
-            ) {
-              if (!styleUpdates) {
-                styleUpdates = {};
-              }
-              styleUpdates[styleName] = nextProp[styleName];
-            }
-          }
-        } else {
-          // Relies on `updateStylesByID` not mutating `styleUpdates`.
-          if (!styleUpdates) {
-            if (!updatePayload) {
-              updatePayload = [];
+      }
+      if (lastProp) {
+        // Unset styles on `lastProp` but not on `nextProp`.
+        for (styleName in lastProp) {
+          if (
+            lastProp.hasOwnProperty(styleName) &&
+            (!nextProp || !nextProp.hasOwnProperty(styleName))
+          ) {
+            if (!styleUpdates) {
+              styleUpdates = {};
             }
-            updatePayload.push(propKey, styleUpdates);
+            styleUpdates[styleName] = '';
           }
-          styleUpdates = nextProp;
         }
-      } else if (propKey === DANGEROUSLY_SET_INNER_HTML) {
-        var nextHtml = nextProp ? nextProp[HTML] : undefined;
-        var lastHtml = lastProp ? lastProp[HTML] : undefined;
-        if (nextHtml != null) {
-          if (lastHtml !== nextHtml) {
-            (updatePayload = updatePayload || []).push(propKey, '' + nextHtml);
+        // Update styles that changed since `lastProp`.
+        for (styleName in nextProp) {
+          if (
+            nextProp.hasOwnProperty(styleName) &&
+            lastProp[styleName] !== nextProp[styleName]
+          ) {
+            if (!styleUpdates) {
+              styleUpdates = {};
+            }
+            styleUpdates[styleName] = nextProp[styleName];
           }
-        } else {
-          // TODO: It might be too late to clear this if we have children
-          // inserted already.
-        }
-      } else if (propKey === CHILDREN) {
-        if (
-          lastProp !== nextProp &&
-          (typeof nextProp === 'string' || typeof nextProp === 'number')
-        ) {
-          (updatePayload = updatePayload || []).push(propKey, '' + nextProp);
         }
-      } else if (propKey === SUPPRESS_CONTENT_EDITABLE_WARNING) {
-        // Noop
-      } else if (registrationNameModules.hasOwnProperty(propKey)) {
-        if (nextProp) {
-          // We eagerly listen to this even though we haven't committed yet.
-          if (__DEV__ && typeof nextProp !== 'function') {
-            warnForInvalidEventListener(propKey, nextProp);
+      } else {
+        // Relies on `updateStylesByID` not mutating `styleUpdates`.
+        if (!styleUpdates) {
+          if (!updatePayload) {
+            updatePayload = [];
           }
-          ensureListeningTo(rootContainerElement, propKey);
+          updatePayload.push(propKey, styleUpdates);
         }
-        if (!updatePayload && lastProp !== nextProp) {
-          // This is a special case. If any listener updates we need to ensure
-          // that the "current" props pointer gets updated so we need a commit
-          // to update this element.
-          updatePayload = [];
+        styleUpdates = nextProp;
+      }
+    } else if (propKey === DANGEROUSLY_SET_INNER_HTML) {
+      var nextHtml = nextProp ? nextProp[HTML] : undefined;
+      var lastHtml = lastProp ? lastProp[HTML] : undefined;
+      if (nextHtml != null) {
+        if (lastHtml !== nextHtml) {
+          (updatePayload = updatePayload || []).push(propKey, '' + nextHtml);
         }
       } else {
-        // For any other property we always add it to the queue and then we
-        // filter it out using the whitelist during the commit.
-        (updatePayload = updatePayload || []).push(propKey, nextProp);
+        // TODO: It might be too late to clear this if we have children
+        // inserted already.
       }
+    } else if (propKey === CHILDREN) {
+      if (
+        lastProp !== nextProp &&
+        (typeof nextProp === 'string' || typeof nextProp === 'number')
+      ) {
+        (updatePayload = updatePayload || []).push(propKey, '' + nextProp);
+      }
+    } else if (propKey === SUPPRESS_CONTENT_EDITABLE_WARNING) {
+      // Noop
+    } else if (registrationNameModules.hasOwnProperty(propKey)) {
+      if (__DEV__ && typeof nextProp !== 'function') {
+        warnForInvalidEventListener(propKey, nextProp);
+      }
+      if (nextProp) {
+        // We eagerly listen to this even though we haven't committed yet.
+        ensureListeningTo(rootContainerElement, propKey);
+      }
+      if (!updatePayload && lastProp !== nextProp) {
+        // This is a special case. If any listener updates we need to ensure
+        // that the "current" props pointer gets updated so we need a commit
+        // to update this element.
+        updatePayload = [];
+      }
+    } else {
+      // For any other property we always add it to the queue and then we
+      // filter it out using the whitelist during the commit.
+      (updatePayload = updatePayload || []).push(propKey, nextProp);
     }
-    if (styleUpdates) {
-      (updatePayload = updatePayload || []).push(STYLE, styleUpdates);
-    }
-    return updatePayload;
-  },
+  }
+  if (styleUpdates) {
+    (updatePayload = updatePayload || []).push(STYLE, styleUpdates);
+  }
+  return updatePayload;
+}
 
+// Apply the diff.
+export function updateProperties(
+  domElement: Element,
+  updatePayload: Array<any>,
+  tag: string,
+  lastRawProps: Object,
+  nextRawProps: Object,
+): void {
+  var wasCustomComponentTag = isCustomComponent(tag, lastRawProps);
+  var isCustomComponentTag = isCustomComponent(tag, nextRawProps);
   // Apply the diff.
-  updateProperties(
-    domElement: Element,
-    updatePayload: Array<any>,
-    tag: string,
-    lastRawProps: Object,
-    nextRawProps: Object,
-  ): void {
-    var wasCustomComponentTag = isCustomComponent(tag, lastRawProps);
-    var isCustomComponentTag = isCustomComponent(tag, nextRawProps);
-    // Apply the diff.
-    updateDOMProperties(
-      domElement,
-      updatePayload,
-      wasCustomComponentTag,
-      isCustomComponentTag,
-    );
+  updateDOMProperties(
+    domElement,
+    updatePayload,
+    wasCustomComponentTag,
+    isCustomComponentTag,
+  );
 
-    // TODO: Ensure that an update gets scheduled if any of the special props
-    // changed.
-    switch (tag) {
-      case 'input':
-        // Update the wrapper around inputs *after* updating props. This has to
-        // happen after `updateDOMProperties`. Otherwise HTML5 input validations
-        // raise warnings and prevent the new value from being assigned.
-        ReactDOMFiberInput.updateWrapper(domElement, nextRawProps);
+  // TODO: Ensure that an update gets scheduled if any of the special props
+  // changed.
+  switch (tag) {
+    case 'input':
+      // Update the wrapper around inputs *after* updating props. This has to
+      // happen after `updateDOMProperties`. Otherwise HTML5 input validations
+      // raise warnings and prevent the new value from being assigned.
+      updateWrapperForInput(domElement, nextRawProps);
 
-        // We also check that we haven't missed a value update, such as a
-        // Radio group shifting the checked value to another named radio input.
-        inputValueTracking.updateValueIfChanged((domElement: any));
-        break;
-      case 'textarea':
-        ReactDOMFiberTextarea.updateWrapper(domElement, nextRawProps);
-        break;
-      case 'select':
-        // <select> value update needs to occur after <option> children
-        // reconciliation
-        ReactDOMFiberSelect.postUpdateWrapper(domElement, nextRawProps);
-        break;
-    }
-  },
+      // We also check that we haven't missed a value update, such as a
+      // Radio group shifting the checked value to another named radio input.
+      updateInputValueIfChanged((domElement: any));
+      break;
+    case 'textarea':
+      updateWrapperForTextarea(domElement, nextRawProps);
+      break;
+    case 'select':
+      // <select> value update needs to occur after <option> children
+      // reconciliation
+      postUpdateWrapperForSelect(domElement, nextRawProps);
+      break;
+  }
+}
 
-  diffHydratedProperties(
-    domElement: Element,
-    tag: string,
-    rawProps: Object,
-    rootContainerElement: Element | Document,
-  ): null | Array<mixed> {
-    if (__DEV__) {
-      var isCustomComponentTag = isCustomComponent(tag, rawProps);
-      validatePropertiesInDevelopment(tag, rawProps);
-      if (isCustomComponentTag && !didWarnShadyDOM && domElement.shadyRoot) {
-        warning(
-          false,
-          '%s is using shady DOM. Using shady DOM with React can ' +
-            'cause things to break subtly.',
-          getCurrentFiberOwnerName() || 'A component',
-        );
-        didWarnShadyDOM = true;
-      }
+export function diffHydratedProperties(
+  domElement: Element,
+  tag: string,
+  rawProps: Object,
+  rootContainerElement: Element | Document,
+): null | Array<mixed> {
+  if (__DEV__) {
+    var isCustomComponentTag = isCustomComponent(tag, rawProps);
+    validatePropertiesInDevelopment(tag, rawProps);
+    if (isCustomComponentTag && !didWarnShadyDOM && domElement.shadyRoot) {
+      warning(
+        false,
+        '%s is using shady DOM. Using shady DOM with React can ' +
+          'cause things to break subtly.',
+        getCurrentFiberOwnerName() || 'A component',
+      );
+      didWarnShadyDOM = true;
     }
+  }
 
-    // TODO: Make sure that we check isMounted before firing any of these events.
-    switch (tag) {
-      case 'iframe':
-      case 'object':
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topLoad',
-          'load',
-          domElement,
-        );
-        break;
-      case 'video':
-      case 'audio':
-        // Create listener for each media event
-        for (var event in mediaEvents) {
-          if (mediaEvents.hasOwnProperty(event)) {
-            ReactBrowserEventEmitter.trapBubbledEvent(
-              event,
-              mediaEvents[event],
-              domElement,
-            );
-          }
+  // TODO: Make sure that we check isMounted before firing any of these events.
+  switch (tag) {
+    case 'iframe':
+    case 'object':
+      trapBubbledEvent('topLoad', 'load', domElement);
+      break;
+    case 'video':
+    case 'audio':
+      // Create listener for each media event
+      for (var event in mediaEvents) {
+        if (mediaEvents.hasOwnProperty(event)) {
+          trapBubbledEvent(event, mediaEvents[event], domElement);
         }
-        break;
-      case 'source':
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topError',
-          'error',
-          domElement,
-        );
-        break;
-      case 'img':
-      case 'image':
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topError',
-          'error',
-          domElement,
-        );
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topLoad',
-          'load',
-          domElement,
-        );
-        break;
-      case 'form':
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topReset',
-          'reset',
-          domElement,
-        );
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topSubmit',
-          'submit',
-          domElement,
-        );
-        break;
-      case 'details':
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topToggle',
-          'toggle',
-          domElement,
-        );
-        break;
-      case 'input':
-        ReactDOMFiberInput.initWrapperState(domElement, rawProps);
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topInvalid',
-          'invalid',
-          domElement,
-        );
-        // For controlled components we always need to ensure we're listening
-        // to onChange. Even if there is no listener.
-        ensureListeningTo(rootContainerElement, 'onChange');
-        break;
-      case 'option':
-        ReactDOMFiberOption.validateProps(domElement, rawProps);
-        break;
-      case 'select':
-        ReactDOMFiberSelect.initWrapperState(domElement, rawProps);
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topInvalid',
-          'invalid',
-          domElement,
-        );
-        // For controlled components we always need to ensure we're listening
-        // to onChange. Even if there is no listener.
-        ensureListeningTo(rootContainerElement, 'onChange');
-        break;
-      case 'textarea':
-        ReactDOMFiberTextarea.initWrapperState(domElement, rawProps);
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topInvalid',
-          'invalid',
-          domElement,
-        );
-        // For controlled components we always need to ensure we're listening
-        // to onChange. Even if there is no listener.
-        ensureListeningTo(rootContainerElement, 'onChange');
-        break;
-    }
+      }
+      break;
+    case 'source':
+      trapBubbledEvent('topError', 'error', domElement);
+      break;
+    case 'img':
+    case 'image':
+      trapBubbledEvent('topError', 'error', domElement);
+      trapBubbledEvent('topLoad', 'load', domElement);
+      break;
+    case 'form':
+      trapBubbledEvent('topReset', 'reset', domElement);
+      trapBubbledEvent('topSubmit', 'submit', domElement);
+      break;
+    case 'details':
+      trapBubbledEvent('topToggle', 'toggle', domElement);
+      break;
+    case 'input':
+      initWrapperStateForInput(domElement, rawProps);
+      trapBubbledEvent('topInvalid', 'invalid', domElement);
+      // For controlled components we always need to ensure we're listening
+      // to onChange. Even if there is no listener.
+      ensureListeningTo(rootContainerElement, 'onChange');
+      break;
+    case 'option':
+      validatePropsForOption(domElement, rawProps);
+      break;
+    case 'select':
+      initWrapperStateForSelect(domElement, rawProps);
+      trapBubbledEvent('topInvalid', 'invalid', domElement);
+      // For controlled components we always need to ensure we're listening
+      // to onChange. Even if there is no listener.
+      ensureListeningTo(rootContainerElement, 'onChange');
+      break;
+    case 'textarea':
+      initWrapperStateForTextarea(domElement, rawProps);
+      trapBubbledEvent('topInvalid', 'invalid', domElement);
+      // For controlled components we always need to ensure we're listening
+      // to onChange. Even if there is no listener.
+      ensureListeningTo(rootContainerElement, 'onChange');
+      break;
+  }
 
-    assertValidProps(tag, rawProps, getCurrentFiberOwnerName);
+  assertValidProps(tag, rawProps, getCurrentFiberOwnerName);
 
-    if (__DEV__) {
-      var extraAttributeNames: Set<string> = new Set();
-      var attributes = domElement.attributes;
-      for (var i = 0; i < attributes.length; i++) {
-        var name = attributes[i].name.toLowerCase();
-        switch (name) {
-          // Built-in SSR attribute is whitelisted
-          case 'data-reactroot':
-            break;
-          // Controlled attributes are not validated
-          // TODO: Only ignore them on controlled tags.
-          case 'value':
-            break;
-          case 'checked':
-            break;
-          case 'selected':
-            break;
-          default:
-            extraAttributeNames.add(attributes[i].name);
-        }
+  if (__DEV__) {
+    var extraAttributeNames: Set<string> = new Set();
+    var attributes = domElement.attributes;
+    for (var i = 0; i < attributes.length; i++) {
+      var name = attributes[i].name.toLowerCase();
+      switch (name) {
+        // Built-in SSR attribute is whitelisted
+        case 'data-reactroot':
+          break;
+        // Controlled attributes are not validated
+        // TODO: Only ignore them on controlled tags.
+        case 'value':
+          break;
+        case 'checked':
+          break;
+        case 'selected':
+          break;
+        default:
+          extraAttributeNames.add(attributes[i].name);
       }
     }
+  }
 
-    var updatePayload = null;
-    for (var propKey in rawProps) {
-      if (!rawProps.hasOwnProperty(propKey)) {
-        continue;
-      }
-      var nextProp = rawProps[propKey];
-      if (propKey === CHILDREN) {
-        // For text content children we compare against textContent. This
-        // might match additional HTML that is hidden when we read it using
-        // textContent. E.g. "foo" will match "f<span>oo</span>" but that still
-        // satisfies our requirement. Our requirement is not to produce perfect
-        // HTML and attributes. Ideally we should preserve structure but it's
-        // ok not to if the visible content is still enough to indicate what
-        // even listeners these nodes might be wired up to.
-        // TODO: Warn if there is more than a single textNode as a child.
-        // TODO: Should we use domElement.firstChild.nodeValue to compare?
-        if (typeof nextProp === 'string') {
-          if (domElement.textContent !== nextProp) {
-            if (__DEV__) {
-              warnForTextDifference(domElement.textContent, nextProp);
-            }
-            updatePayload = [CHILDREN, nextProp];
+  var updatePayload = null;
+  for (var propKey in rawProps) {
+    if (!rawProps.hasOwnProperty(propKey)) {
+      continue;
+    }
+    var nextProp = rawProps[propKey];
+    if (propKey === CHILDREN) {
+      // For text content children we compare against textContent. This
+      // might match additional HTML that is hidden when we read it using
+      // textContent. E.g. "foo" will match "f<span>oo</span>" but that still
+      // satisfies our requirement. Our requirement is not to produce perfect
+      // HTML and attributes. Ideally we should preserve structure but it's
+      // ok not to if the visible content is still enough to indicate what
+      // even listeners these nodes might be wired up to.
+      // TODO: Warn if there is more than a single textNode as a child.
+      // TODO: Should we use domElement.firstChild.nodeValue to compare?
+      if (typeof nextProp === 'string') {
+        if (domElement.textContent !== nextProp) {
+          if (__DEV__) {
+            warnForTextDifference(domElement.textContent, nextProp);
           }
-        } else if (typeof nextProp === 'number') {
-          if (domElement.textContent !== '' + nextProp) {
-            if (__DEV__) {
-              warnForTextDifference(domElement.textContent, nextProp);
-            }
-            updatePayload = [CHILDREN, '' + nextProp];
+          updatePayload = [CHILDREN, nextProp];
+        }
+      } else if (typeof nextProp === 'number') {
+        if (domElement.textContent !== '' + nextProp) {
+          if (__DEV__) {
+            warnForTextDifference(domElement.textContent, nextProp);
           }
+          updatePayload = [CHILDREN, '' + nextProp];
+        }
+      }
+    } else if (registrationNameModules.hasOwnProperty(propKey)) {
+      if (__DEV__ && typeof nextProp !== 'function') {
+        warnForInvalidEventListener(propKey, nextProp);
+      }
+      if (nextProp) {
+        ensureListeningTo(rootContainerElement, propKey);
+      }
+    } else if (__DEV__) {
+      // Validate that the properties correspond to their expected values.
+      var serverValue;
+      var propertyInfo;
+      if (
+        propKey === SUPPRESS_CONTENT_EDITABLE_WARNING ||
+        // Controlled attributes are not validated
+        // TODO: Only ignore them on controlled tags.
+        propKey === 'value' ||
+        propKey === 'checked' ||
+        propKey === 'selected'
+      ) {
+        // Noop
+      } else if (propKey === DANGEROUSLY_SET_INNER_HTML) {
+        const rawHtml = nextProp ? nextProp[HTML] || '' : '';
+        const serverHTML = domElement.innerHTML;
+        const expectedHTML = normalizeHTML(domElement, rawHtml);
+        if (expectedHTML !== serverHTML) {
+          warnForPropDifference(propKey, serverHTML, expectedHTML);
         }
-      } else if (registrationNameModules.hasOwnProperty(propKey)) {
-        if (__DEV__ && typeof nextProp !== 'function') {
-          warnForInvalidEventListener(propKey, nextProp);
+      } else if (propKey === STYLE) {
+        // $FlowFixMe - Should be inferred as not undefined.
+        extraAttributeNames.delete(propKey);
+        const expectedStyle = createDangerousStringForStyles(nextProp);
+        serverValue = domElement.getAttribute('style');
+        if (expectedStyle !== serverValue) {
+          warnForPropDifference(propKey, serverValue, expectedStyle);
         }
-        if (nextProp) {
-          ensureListeningTo(rootContainerElement, propKey);
+      } else if (isCustomComponentTag) {
+        // $FlowFixMe - Should be inferred as not undefined.
+        extraAttributeNames.delete(propKey.toLowerCase());
+        serverValue = getValueForAttribute(domElement, propKey, nextProp);
+
+        if (nextProp !== serverValue) {
+          warnForPropDifference(propKey, serverValue, nextProp);
         }
-      } else if (__DEV__) {
-        // Validate that the properties correspond to their expected values.
-        var serverValue;
-        var propertyInfo;
-        if (
-          propKey === SUPPRESS_CONTENT_EDITABLE_WARNING ||
-          // Controlled attributes are not validated
-          // TODO: Only ignore them on controlled tags.
-          propKey === 'value' ||
-          propKey === 'checked' ||
-          propKey === 'selected'
-        ) {
-          // Noop
-        } else if (propKey === DANGEROUSLY_SET_INNER_HTML) {
-          const rawHtml = nextProp ? nextProp[HTML] || '' : '';
-          const serverHTML = domElement.innerHTML;
-          const expectedHTML = normalizeHTML(domElement, rawHtml);
-          if (expectedHTML !== serverHTML) {
-            warnForPropDifference(propKey, serverHTML, expectedHTML);
-          }
-        } else if (propKey === STYLE) {
+      } else if (shouldSetAttribute(propKey, nextProp)) {
+        if ((propertyInfo = getPropertyInfo(propKey))) {
           // $FlowFixMe - Should be inferred as not undefined.
-          extraAttributeNames.delete(propKey);
-          const expectedStyle = CSSPropertyOperations.createDangerousStringForStyles(
-            nextProp,
-          );
-          serverValue = domElement.getAttribute('style');
-          if (expectedStyle !== serverValue) {
-            warnForPropDifference(propKey, serverValue, expectedStyle);
-          }
-        } else if (isCustomComponentTag) {
+          extraAttributeNames.delete(propertyInfo.attributeName);
+          serverValue = getValueForProperty(domElement, propKey, nextProp);
+        } else {
           // $FlowFixMe - Should be inferred as not undefined.
           extraAttributeNames.delete(propKey.toLowerCase());
-          serverValue = DOMPropertyOperations.getValueForAttribute(
-            domElement,
-            propKey,
-            nextProp,
-          );
-
-          if (nextProp !== serverValue) {
-            warnForPropDifference(propKey, serverValue, nextProp);
-          }
-        } else if (DOMProperty.shouldSetAttribute(propKey, nextProp)) {
-          if ((propertyInfo = DOMProperty.getPropertyInfo(propKey))) {
-            // $FlowFixMe - Should be inferred as not undefined.
-            extraAttributeNames.delete(propertyInfo.attributeName);
-            serverValue = DOMPropertyOperations.getValueForProperty(
-              domElement,
-              propKey,
-              nextProp,
-            );
-          } else {
-            // $FlowFixMe - Should be inferred as not undefined.
-            extraAttributeNames.delete(propKey.toLowerCase());
-            serverValue = DOMPropertyOperations.getValueForAttribute(
-              domElement,
-              propKey,
-              nextProp,
-            );
-          }
+          serverValue = getValueForAttribute(domElement, propKey, nextProp);
+        }
 
-          if (nextProp !== serverValue) {
-            warnForPropDifference(propKey, serverValue, nextProp);
-          }
+        if (nextProp !== serverValue) {
+          warnForPropDifference(propKey, serverValue, nextProp);
         }
       }
     }
+  }
 
-    if (__DEV__) {
+  if (__DEV__) {
+    // $FlowFixMe - Should be inferred as not undefined.
+    if (extraAttributeNames.size > 0) {
       // $FlowFixMe - Should be inferred as not undefined.
-      if (extraAttributeNames.size > 0) {
-        // $FlowFixMe - Should be inferred as not undefined.
-        warnForExtraAttributes(extraAttributeNames);
-      }
+      warnForExtraAttributes(extraAttributeNames);
     }
+  }
 
-    switch (tag) {
-      case 'input':
-        // TODO: Make sure we check if this is still unmounted or do any clean
-        // up necessary since we never stop tracking anymore.
-        inputValueTracking.track((domElement: any));
-        ReactDOMFiberInput.postMountWrapper(domElement, rawProps);
-        break;
-      case 'textarea':
-        // TODO: Make sure we check if this is still unmounted or do any clean
-        // up necessary since we never stop tracking anymore.
-        inputValueTracking.track((domElement: any));
-        ReactDOMFiberTextarea.postMountWrapper(domElement, rawProps);
-        break;
-      case 'select':
-      case 'option':
-        // For input and textarea we current always set the value property at
-        // post mount to force it to diverge from attributes. However, for
-        // option and select we don't quite do the same thing and select
-        // is not resilient to the DOM state changing so we don't do that here.
-        // TODO: Consider not doing this for input and textarea.
-        break;
-      default:
-        if (typeof rawProps.onClick === 'function') {
-          // TODO: This cast may not be sound for SVG, MathML or custom elements.
-          trapClickOnNonInteractiveElement(((domElement: any): HTMLElement));
-        }
-        break;
-    }
+  switch (tag) {
+    case 'input':
+      // TODO: Make sure we check if this is still unmounted or do any clean
+      // up necessary since we never stop tracking anymore.
+      trackInputValue((domElement: any));
+      postMountWrapperForInput(domElement, rawProps);
+      break;
+    case 'textarea':
+      // TODO: Make sure we check if this is still unmounted or do any clean
+      // up necessary since we never stop tracking anymore.
+      trackInputValue((domElement: any));
+      postMountWrapperForTextarea(domElement, rawProps);
+      break;
+    case 'select':
+    case 'option':
+      // For input and textarea we current always set the value property at
+      // post mount to force it to diverge from attributes. However, for
+      // option and select we don't quite do the same thing and select
+      // is not resilient to the DOM state changing so we don't do that here.
+      // TODO: Consider not doing this for input and textarea.
+      break;
+    default:
+      if (typeof rawProps.onClick === 'function') {
+        // TODO: This cast may not be sound for SVG, MathML or custom elements.
+        trapClickOnNonInteractiveElement(((domElement: any): HTMLElement));
+      }
+      break;
+  }
 
-    return updatePayload;
-  },
+  return updatePayload;
+}
 
-  diffHydratedText(textNode: Text, text: string): boolean {
-    const isDifferent = textNode.nodeValue !== text;
-    if (__DEV__) {
-      if (isDifferent) {
-        warnForTextDifference(textNode.nodeValue, text);
-      }
+export function diffHydratedText(textNode: Text, text: string): boolean {
+  const isDifferent = textNode.nodeValue !== text;
+  if (__DEV__) {
+    if (isDifferent) {
+      warnForTextDifference(textNode.nodeValue, text);
     }
-    return isDifferent;
-  },
+  }
+  return isDifferent;
+}
 
-  warnForDeletedHydratableElement(
-    parentNode: Element | Document,
-    child: Element,
-  ) {
-    if (__DEV__) {
-      if (didWarnInvalidHydration) {
-        return;
-      }
-      didWarnInvalidHydration = true;
-      warning(
-        false,
-        'Did not expect server HTML to contain a <%s> in <%s>.',
-        child.nodeName.toLowerCase(),
-        parentNode.nodeName.toLowerCase(),
-      );
+export function warnForDeletedHydratableElement(
+  parentNode: Element | Document,
+  child: Element,
+) {
+  if (__DEV__) {
+    if (didWarnInvalidHydration) {
+      return;
     }
-  },
+    didWarnInvalidHydration = true;
+    warning(
+      false,
+      'Did not expect server HTML to contain a <%s> in <%s>.',
+      child.nodeName.toLowerCase(),
+      parentNode.nodeName.toLowerCase(),
+    );
+  }
+}
 
-  warnForDeletedHydratableText(parentNode: Element | Document, child: Text) {
-    if (__DEV__) {
-      if (didWarnInvalidHydration) {
-        return;
-      }
-      didWarnInvalidHydration = true;
-      warning(
-        false,
-        'Did not expect server HTML to contain the text node "%s" in <%s>.',
-        child.nodeValue,
-        parentNode.nodeName.toLowerCase(),
-      );
+export function warnForDeletedHydratableText(
+  parentNode: Element | Document,
+  child: Text,
+) {
+  if (__DEV__) {
+    if (didWarnInvalidHydration) {
+      return;
     }
-  },
+    didWarnInvalidHydration = true;
+    warning(
+      false,
+      'Did not expect server HTML to contain the text node "%s" in <%s>.',
+      child.nodeValue,
+      parentNode.nodeName.toLowerCase(),
+    );
+  }
+}
 
-  warnForInsertedHydratedElement(
-    parentNode: Element | Document,
-    tag: string,
-    props: Object,
-  ) {
-    if (__DEV__) {
-      if (didWarnInvalidHydration) {
-        return;
-      }
-      didWarnInvalidHydration = true;
-      warning(
-        false,
-        'Expected server HTML to contain a matching <%s> in <%s>.',
-        tag,
-        parentNode.nodeName.toLowerCase(),
-      );
+export function warnForInsertedHydratedElement(
+  parentNode: Element | Document,
+  tag: string,
+  props: Object,
+) {
+  if (__DEV__) {
+    if (didWarnInvalidHydration) {
+      return;
     }
-  },
+    didWarnInvalidHydration = true;
+    warning(
+      false,
+      'Expected server HTML to contain a matching <%s> in <%s>.',
+      tag,
+      parentNode.nodeName.toLowerCase(),
+    );
+  }
+}
 
-  warnForInsertedHydratedText(parentNode: Element | Document, text: string) {
-    if (__DEV__) {
-      if (text === '') {
-        // We expect to insert empty text nodes since they're not represented in
-        // the HTML.
-        // TODO: Remove this special case if we can just avoid inserting empty
-        // text nodes.
-        return;
-      }
-      if (didWarnInvalidHydration) {
-        return;
-      }
-      didWarnInvalidHydration = true;
-      warning(
-        false,
-        'Expected server HTML to contain a matching text node for "%s" in <%s>.',
-        text,
-        parentNode.nodeName.toLowerCase(),
-      );
+export function warnForInsertedHydratedText(
+  parentNode: Element | Document,
+  text: string,
+) {
+  if (__DEV__) {
+    if (text === '') {
+      // We expect to insert empty text nodes since they're not represented in
+      // the HTML.
+      // TODO: Remove this special case if we can just avoid inserting empty
+      // text nodes.
+      return;
     }
-  },
-
-  restoreControlledState(
-    domElement: Element,
-    tag: string,
-    props: Object,
-  ): void {
-    switch (tag) {
-      case 'input':
-        ReactDOMFiberInput.restoreControlledState(domElement, props);
-        return;
-      case 'textarea':
-        ReactDOMFiberTextarea.restoreControlledState(domElement, props);
-        return;
-      case 'select':
-        ReactDOMFiberSelect.restoreControlledState(domElement, props);
-        return;
+    if (didWarnInvalidHydration) {
+      return;
     }
-  },
-};
+    didWarnInvalidHydration = true;
+    warning(
+      false,
+      'Expected server HTML to contain a matching text node for "%s" in <%s>.',
+      text,
+      parentNode.nodeName.toLowerCase(),
+    );
+  }
+}
 
-module.exports = ReactDOMFiberComponent;
+export function restoreControlledState(
+  domElement: Element,
+  tag: string,
+  props: Object,
+): void {
+  switch (tag) {
+    case 'input':
+      restoreControlledStateForInput(domElement, props);
+      return;
+    case 'textarea':
+      restoreControlledStateForTextarea(domElement, props);
+      return;
+    case 'select':
+      restoreControlledStateForSelect(domElement, props);
+      return;
+  }
+}
diff --git a/src/renderers/dom/fiber/ReactDOMFiberEntry.js b/src/renderers/dom/fiber/ReactDOMFiberEntry.js
index e7a25947121..c5397f9ea8c 100644
--- a/src/renderers/dom/fiber/ReactDOMFiberEntry.js
+++ b/src/renderers/dom/fiber/ReactDOMFiberEntry.js
@@ -12,60 +12,77 @@
 
 'use strict';
 
-import type {Fiber} from 'ReactFiber';
 import type {ReactNodeList} from 'ReactTypes';
 
-require('checkReact');
-var DOMNamespaces = require('DOMNamespaces');
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
-var ReactBrowserEventEmitter = require('ReactBrowserEventEmitter');
-var ReactControlledComponent = require('ReactControlledComponent');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactFeatureFlags = require('ReactFeatureFlags');
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-var ReactDOMFiberComponent = require('ReactDOMFiberComponent');
-var ReactDOMFrameScheduling = require('ReactDOMFrameScheduling');
-var ReactGenericBatching = require('ReactGenericBatching');
-var ReactFiberReconciler = require('ReactFiberReconciler');
-var ReactInputSelection = require('ReactInputSelection');
-var ReactInstanceMap = require('ReactInstanceMap');
-var ReactPortal = require('ReactPortal');
-var ReactVersion = require('ReactVersion');
-var {isValidElement} = require('react');
-var {injectInternals} = require('ReactFiberDevToolsHook');
-var {
-  ELEMENT_NODE,
-  TEXT_NODE,
-  COMMENT_NODE,
-  DOCUMENT_NODE,
-  DOCUMENT_FRAGMENT_NODE,
-} = require('HTMLNodeType');
-var {ROOT_ATTRIBUTE_NAME} = require('DOMProperty');
-
-var findDOMNode = require('findDOMNode');
-var invariant = require('fbjs/lib/invariant');
-
-var {getChildNamespace} = DOMNamespaces;
-var {
+import 'checkReact';
+import 'ReactDOMClientInjection';
+import 'ReactDOMInjection';
+import {getChildNamespace} from 'DOMNamespaces';
+import ExecutionEnvironment from 'fbjs/lib/ExecutionEnvironment';
+import {
+  isEnabled as isEventEmitterEnabled,
+  setEnabled as setEventEmitterEnabled,
+} from 'ReactBrowserEventEmitter';
+import {
+  injection as ReactControlledComponentInjection,
+} from 'ReactControlledComponent';
+import {
+  getClosestInstanceFromNode,
+  getInstanceFromNode,
+  precacheFiberNode,
+  updateFiberProps,
+} from 'ReactDOMComponentTree';
+import ReactFeatureFlags from 'ReactFeatureFlags';
+import ReactDOMFeatureFlags from 'ReactDOMFeatureFlags';
+import {
   createElement,
   setInitialProperties,
   diffProperties,
   updateProperties,
   diffHydratedProperties,
   diffHydratedText,
+  restoreControlledState,
   warnForDeletedHydratableElement,
   warnForDeletedHydratableText,
   warnForInsertedHydratedElement,
   warnForInsertedHydratedText,
-} = ReactDOMFiberComponent;
-var {precacheFiberNode, updateFiberProps} = ReactDOMComponentTree;
+} from 'ReactDOMFiberComponent';
+import {rIC} from 'ReactDOMFrameScheduling';
+import {
+  injection as ReactGenericBatchingInjection,
+  batchedUpdates,
+} from 'ReactGenericBatching';
+import ReactFiberReconciler from 'ReactFiberReconciler';
+import {getSelectionInformation, restoreSelection} from 'ReactInputSelection';
+import ReactInstanceMap from 'ReactInstanceMap';
+import {createPortal} from 'ReactPortal';
+import ReactVersion from 'ReactVersion';
+import {ReactCurrentOwner} from 'ReactGlobalSharedState';
+import React from 'react';
+import {injectInternals} from 'ReactFiberDevToolsHook';
+import {
+  ELEMENT_NODE,
+  TEXT_NODE,
+  COMMENT_NODE,
+  DOCUMENT_NODE,
+  DOCUMENT_FRAGMENT_NODE,
+} from 'HTMLNodeType';
+import {ROOT_ATTRIBUTE_NAME} from 'DOMProperty';
+import getComponentName from 'getComponentName';
+import invariant from 'fbjs/lib/invariant';
+import lowPriorityWarning from 'lowPriorityWarning';
+import warning from 'fbjs/lib/warning';
+import {validateDOMNesting, updatedAncestorInfo} from 'validateDOMNesting';
+
+// TODO: we can remove these when we stop exposing them as secrets exports.
+import * as ReactControlledComponent from 'ReactControlledComponent';
+import * as ReactDOMComponentTree from 'ReactDOMComponentTree';
+import * as ReactDOMEventListener from 'ReactDOMEventListener';
+import * as EventPluginHub from 'EventPluginHub';
+import * as EventPluginRegistry from 'EventPluginRegistry';
+import * as EventPropagators from 'EventPropagators';
 
 if (__DEV__) {
-  var lowPriorityWarning = require('lowPriorityWarning');
-  var warning = require('fbjs/lib/warning');
-  var validateDOMNesting = require('validateDOMNesting');
-  var {updatedAncestorInfo} = validateDOMNesting;
-
   if (
     typeof Map !== 'function' ||
     Map.prototype == null ||
@@ -83,14 +100,9 @@ if (__DEV__) {
   }
 }
 
-require('ReactDOMClientInjection');
-require('ReactDOMInjection');
-ReactControlledComponent.injection.injectFiberControlledHostComponent(
-  ReactDOMFiberComponent,
+ReactControlledComponentInjection.injectRestoreStateImplementation(
+  restoreControlledState,
 );
-findDOMNode._injectFiber(function(fiber: Fiber) {
-  return DOMRenderer.findHostInstance(fiber);
-});
 
 type DOMContainer =
   | (Element & {
@@ -212,15 +224,15 @@ var DOMRenderer = ReactFiberReconciler({
   },
 
   prepareForCommit(): void {
-    eventsEnabled = ReactBrowserEventEmitter.isEnabled();
-    selectionInformation = ReactInputSelection.getSelectionInformation();
-    ReactBrowserEventEmitter.setEnabled(false);
+    eventsEnabled = isEventEmitterEnabled();
+    selectionInformation = getSelectionInformation();
+    setEventEmitterEnabled(false);
   },
 
   resetAfterCommit(): void {
-    ReactInputSelection.restoreSelection(selectionInformation);
+    restoreSelection(selectionInformation);
     selectionInformation = null;
-    ReactBrowserEventEmitter.setEnabled(eventsEnabled);
+    setEventEmitterEnabled(eventsEnabled);
     eventsEnabled = null;
   },
 
@@ -235,7 +247,7 @@ var DOMRenderer = ReactFiberReconciler({
     if (__DEV__) {
       // TODO: take namespace into account when validating.
       const hostContextDev = ((hostContext: any): HostContextDev);
-      validateDOMNesting(type, null, null, hostContextDev.ancestorInfo);
+      validateDOMNesting(type, null, hostContextDev.ancestorInfo);
       if (
         typeof props.children === 'string' ||
         typeof props.children === 'number'
@@ -246,7 +258,7 @@ var DOMRenderer = ReactFiberReconciler({
           type,
           null,
         );
-        validateDOMNesting(null, string, null, ownAncestorInfo);
+        validateDOMNesting(null, string, ownAncestorInfo);
       }
       parentNamespace = hostContextDev.namespace;
     } else {
@@ -301,7 +313,7 @@ var DOMRenderer = ReactFiberReconciler({
           type,
           null,
         );
-        validateDOMNesting(null, string, null, ownAncestorInfo);
+        validateDOMNesting(null, string, ownAncestorInfo);
       }
     }
     return diffProperties(
@@ -368,7 +380,7 @@ var DOMRenderer = ReactFiberReconciler({
   ): TextInstance {
     if (__DEV__) {
       const hostContextDev = ((hostContext: any): HostContextDev);
-      validateDOMNesting(null, text, null, hostContextDev.ancestorInfo);
+      validateDOMNesting(null, text, hostContextDev.ancestorInfo);
     }
     var textNode: TextInstance = document.createTextNode(text);
     precacheFiberNode(internalInstanceHandle, textNode);
@@ -534,12 +546,12 @@ var DOMRenderer = ReactFiberReconciler({
     warnForInsertedHydratedText(parentInstance, text);
   },
 
-  scheduleDeferredCallback: ReactDOMFrameScheduling.rIC,
+  scheduleDeferredCallback: rIC,
 
   useSyncScheduling: !ReactDOMFeatureFlags.fiberAsyncScheduling,
 });
 
-ReactGenericBatching.injection.injectFiberBatchedUpdates(
+ReactGenericBatchingInjection.injectBatchedUpdatesImplementation(
   DOMRenderer.batchedUpdates,
 );
 
@@ -575,8 +587,7 @@ function renderSubtreeIntoContainer(
 
     const isRootRenderedBySomeReact = !!container._reactRootContainer;
     const rootEl = getReactRootElementInContainer(container);
-    const hasNonRootReactChild = !!(rootEl &&
-      ReactDOMComponentTree.getInstanceFromNode(rootEl));
+    const hasNonRootReactChild = !!(rootEl && getInstanceFromNode(rootEl));
 
     warning(
       !hasNonRootReactChild || isRootRenderedBySomeReact,
@@ -649,6 +660,48 @@ function renderSubtreeIntoContainer(
 }
 
 var ReactDOMFiber = {
+  findDOMNode(
+    componentOrElement: Element | ?ReactComponent<any, any, any>,
+  ): null | Element | Text {
+    if (__DEV__) {
+      var owner = (ReactCurrentOwner.current: any);
+      if (owner !== null) {
+        var warnedAboutRefsInRender = owner.stateNode._warnedAboutRefsInRender;
+        warning(
+          warnedAboutRefsInRender,
+          '%s is accessing findDOMNode inside its render(). ' +
+            'render() should be a pure function of props and state. It should ' +
+            'never access something that requires stale data from the previous ' +
+            'render, such as refs. Move this logic to componentDidMount and ' +
+            'componentDidUpdate instead.',
+          getComponentName(owner) || 'A component',
+        );
+        owner.stateNode._warnedAboutRefsInRender = true;
+      }
+    }
+    if (componentOrElement == null) {
+      return null;
+    }
+    if ((componentOrElement: any).nodeType === ELEMENT_NODE) {
+      return (componentOrElement: any);
+    }
+
+    var inst = ReactInstanceMap.get(componentOrElement);
+    if (inst) {
+      return DOMRenderer.findHostInstance(inst);
+    }
+
+    if (typeof componentOrElement.render === 'function') {
+      invariant(false, 'Unable to find node on an unmounted component.');
+    } else {
+      invariant(
+        false,
+        'Element appears to be neither ReactComponent nor DOMNode. Keys: %s',
+        Object.keys(componentOrElement),
+      );
+    }
+  },
+
   hydrate(
     element: ReactElement<any>,
     container: DOMContainer,
@@ -667,7 +720,7 @@ var ReactDOMFiber = {
       // Top-level check occurs here instead of inside child reconciler
       // because requirements vary between renderers. E.g. React Art
       // allows arrays.
-      if (!isValidElement(element)) {
+      if (!React.isValidElement(element)) {
         if (typeof element === 'string') {
           invariant(
             false,
@@ -732,8 +785,7 @@ var ReactDOMFiber = {
     if (container._reactRootContainer) {
       if (__DEV__) {
         const rootEl = getReactRootElementInContainer(container);
-        const renderedByDifferentReact =
-          rootEl && !ReactDOMComponentTree.getInstanceFromNode(rootEl);
+        const renderedByDifferentReact = rootEl && !getInstanceFromNode(rootEl);
         warning(
           !renderedByDifferentReact,
           "unmountComponentAtNode(): The node you're attempting to unmount " +
@@ -753,8 +805,7 @@ var ReactDOMFiber = {
     } else {
       if (__DEV__) {
         const rootEl = getReactRootElementInContainer(container);
-        const hasNonRootReactChild = !!(rootEl &&
-          ReactDOMComponentTree.getInstanceFromNode(rootEl));
+        const hasNonRootReactChild = !!(rootEl && getInstanceFromNode(rootEl));
 
         // Check if the container itself is a React root node.
         const isContainerReactRoot =
@@ -778,18 +829,16 @@ var ReactDOMFiber = {
     }
   },
 
-  findDOMNode: findDOMNode,
-
   unstable_createPortal(
     children: ReactNodeList,
     container: DOMContainer,
     key: ?string = null,
   ) {
     // TODO: pass ReactDOM portal implementation as third argument
-    return ReactPortal.createPortal(children, container, null, key);
+    return createPortal(children, container, null, key);
   },
 
-  unstable_batchedUpdates: ReactGenericBatching.batchedUpdates,
+  unstable_batchedUpdates: batchedUpdates,
 
   unstable_deferredUpdates: DOMRenderer.deferredUpdates,
 
@@ -797,18 +846,18 @@ var ReactDOMFiber = {
 
   __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: {
     // For TapEventPlugin which is popular in open source
-    EventPluginHub: require('EventPluginHub'),
+    EventPluginHub,
     // Used by test-utils
-    EventPluginRegistry: require('EventPluginRegistry'),
-    EventPropagators: require('EventPropagators'),
+    EventPluginRegistry,
+    EventPropagators,
     ReactControlledComponent,
     ReactDOMComponentTree,
-    ReactDOMEventListener: require('ReactDOMEventListener'),
+    ReactDOMEventListener,
   },
 };
 
 const foundDevTools = injectInternals({
-  findFiberByHostInstance: ReactDOMComponentTree.getClosestInstanceFromNode,
+  findFiberByHostInstance: getClosestInstanceFromNode,
   findHostInstanceByFiber: DOMRenderer.findHostInstance,
   // This is an enum because we may add more (e.g. profiler build)
   bundleType: __DEV__ ? 1 : 0,
@@ -846,4 +895,4 @@ if (__DEV__) {
   }
 }
 
-module.exports = ReactDOMFiber;
+export default ReactDOMFiber;
diff --git a/src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js b/src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js
index 2910041d9bb..30ee7088ec5 100644
--- a/src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js
+++ b/src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js
@@ -13,7 +13,6 @@
 
 var React = require('react');
 var ReactDOM = require('react-dom');
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 var ReactTestUtils = require('react-dom/test-utils');
 var PropTypes = require('prop-types');
 
@@ -84,1024 +83,1017 @@ describe('ReactDOMFiber', () => {
     expect(called).toEqual(true);
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    it('should render a component returning strings directly from render', () => {
-      const Text = ({value}) => value;
+  it('should render a component returning strings directly from render', () => {
+    const Text = ({value}) => value;
 
-      ReactDOM.render(<Text value="foo" />, container);
-      expect(container.textContent).toEqual('foo');
-    });
+    ReactDOM.render(<Text value="foo" />, container);
+    expect(container.textContent).toEqual('foo');
+  });
 
-    it('should render a component returning numbers directly from render', () => {
-      const Text = ({value}) => value;
+  it('should render a component returning numbers directly from render', () => {
+    const Text = ({value}) => value;
 
-      ReactDOM.render(<Text value={10} />, container);
+    ReactDOM.render(<Text value={10} />, container);
 
-      expect(container.textContent).toEqual('10');
-    });
+    expect(container.textContent).toEqual('10');
+  });
 
-    it('finds the DOM Text node of a string child', () => {
-      class Text extends React.Component {
-        render() {
-          return this.props.value;
-        }
+  it('finds the DOM Text node of a string child', () => {
+    class Text extends React.Component {
+      render() {
+        return this.props.value;
       }
+    }
 
-      let instance = null;
-      ReactDOM.render(
-        <Text value="foo" ref={ref => (instance = ref)} />,
-        container,
-      );
+    let instance = null;
+    ReactDOM.render(
+      <Text value="foo" ref={ref => (instance = ref)} />,
+      container,
+    );
 
-      const textNode = ReactDOM.findDOMNode(instance);
-      expect(textNode).toBe(container.firstChild);
-      expect(textNode.nodeType).toBe(3);
-      expect(textNode.nodeValue).toBe('foo');
-    });
+    const textNode = ReactDOM.findDOMNode(instance);
+    expect(textNode).toBe(container.firstChild);
+    expect(textNode.nodeType).toBe(3);
+    expect(textNode.nodeValue).toBe('foo');
+  });
 
-    it('finds the first child when a component returns a fragment', () => {
-      class Fragment extends React.Component {
-        render() {
-          return [<div key="a" />, <span key="b" />];
-        }
+  it('finds the first child when a component returns a fragment', () => {
+    class Fragment extends React.Component {
+      render() {
+        return [<div key="a" />, <span key="b" />];
       }
+    }
 
-      let instance = null;
-      ReactDOM.render(<Fragment ref={ref => (instance = ref)} />, container);
+    let instance = null;
+    ReactDOM.render(<Fragment ref={ref => (instance = ref)} />, container);
 
-      expect(container.childNodes.length).toBe(2);
+    expect(container.childNodes.length).toBe(2);
 
-      const firstNode = ReactDOM.findDOMNode(instance);
-      expect(firstNode).toBe(container.firstChild);
-      expect(firstNode.tagName).toBe('DIV');
-    });
+    const firstNode = ReactDOM.findDOMNode(instance);
+    expect(firstNode).toBe(container.firstChild);
+    expect(firstNode.tagName).toBe('DIV');
+  });
 
-    it('finds the first child even when fragment is nested', () => {
-      class Wrapper extends React.Component {
-        render() {
-          return this.props.children;
-        }
+  it('finds the first child even when fragment is nested', () => {
+    class Wrapper extends React.Component {
+      render() {
+        return this.props.children;
       }
+    }
 
-      class Fragment extends React.Component {
-        render() {
-          return [<Wrapper key="a"><div /></Wrapper>, <span key="b" />];
-        }
+    class Fragment extends React.Component {
+      render() {
+        return [<Wrapper key="a"><div /></Wrapper>, <span key="b" />];
       }
+    }
 
-      let instance = null;
-      ReactDOM.render(<Fragment ref={ref => (instance = ref)} />, container);
+    let instance = null;
+    ReactDOM.render(<Fragment ref={ref => (instance = ref)} />, container);
 
-      expect(container.childNodes.length).toBe(2);
+    expect(container.childNodes.length).toBe(2);
 
-      const firstNode = ReactDOM.findDOMNode(instance);
-      expect(firstNode).toBe(container.firstChild);
-      expect(firstNode.tagName).toBe('DIV');
-    });
+    const firstNode = ReactDOM.findDOMNode(instance);
+    expect(firstNode).toBe(container.firstChild);
+    expect(firstNode.tagName).toBe('DIV');
+  });
 
-    it('finds the first child even when first child renders null', () => {
-      class NullComponent extends React.Component {
-        render() {
-          return null;
-        }
+  it('finds the first child even when first child renders null', () => {
+    class NullComponent extends React.Component {
+      render() {
+        return null;
       }
+    }
 
-      class Fragment extends React.Component {
-        render() {
-          return [<NullComponent key="a" />, <div key="b" />, <span key="c" />];
-        }
+    class Fragment extends React.Component {
+      render() {
+        return [<NullComponent key="a" />, <div key="b" />, <span key="c" />];
       }
+    }
 
-      let instance = null;
-      ReactDOM.render(<Fragment ref={ref => (instance = ref)} />, container);
+    let instance = null;
+    ReactDOM.render(<Fragment ref={ref => (instance = ref)} />, container);
 
-      expect(container.childNodes.length).toBe(2);
+    expect(container.childNodes.length).toBe(2);
 
-      const firstNode = ReactDOM.findDOMNode(instance);
-      expect(firstNode).toBe(container.firstChild);
-      expect(firstNode.tagName).toBe('DIV');
-    });
-  }
+    const firstNode = ReactDOM.findDOMNode(instance);
+    expect(firstNode).toBe(container.firstChild);
+    expect(firstNode.tagName).toBe('DIV');
+  });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    var svgEls, htmlEls, mathEls;
-    var expectSVG = {ref: el => svgEls.push(el)};
-    var expectHTML = {ref: el => htmlEls.push(el)};
-    var expectMath = {ref: el => mathEls.push(el)};
+  var svgEls, htmlEls, mathEls;
+  var expectSVG = {ref: el => svgEls.push(el)};
+  var expectHTML = {ref: el => htmlEls.push(el)};
+  var expectMath = {ref: el => mathEls.push(el)};
 
-    var usePortal = function(tree) {
-      return ReactDOM.unstable_createPortal(
-        tree,
-        document.createElement('div'),
-      );
-    };
-
-    var assertNamespacesMatch = function(tree) {
-      container = document.createElement('div');
-      svgEls = [];
-      htmlEls = [];
-      mathEls = [];
-
-      ReactDOM.render(tree, container);
-      svgEls.forEach(el => {
-        expect(el.namespaceURI).toBe('http://www.w3.org/2000/svg');
-      });
-      htmlEls.forEach(el => {
-        expect(el.namespaceURI).toBe('http://www.w3.org/1999/xhtml');
-      });
-      mathEls.forEach(el => {
-        expect(el.namespaceURI).toBe('http://www.w3.org/1998/Math/MathML');
-      });
-
-      ReactDOM.unmountComponentAtNode(container);
-      expect(container.innerHTML).toBe('');
-    };
-
-    it('should render one portal', () => {
-      var portalContainer = document.createElement('div');
-
-      ReactDOM.render(
-        <div>
-          {ReactDOM.unstable_createPortal(<div>portal</div>, portalContainer)}
-        </div>,
-        container,
-      );
-      expect(portalContainer.innerHTML).toBe('<div>portal</div>');
-      expect(container.innerHTML).toBe('<div></div>');
+  var usePortal = function(tree) {
+    return ReactDOM.unstable_createPortal(tree, document.createElement('div'));
+  };
 
-      ReactDOM.unmountComponentAtNode(container);
-      expect(portalContainer.innerHTML).toBe('');
-      expect(container.innerHTML).toBe('');
+  var assertNamespacesMatch = function(tree) {
+    container = document.createElement('div');
+    svgEls = [];
+    htmlEls = [];
+    mathEls = [];
+
+    ReactDOM.render(tree, container);
+    svgEls.forEach(el => {
+      expect(el.namespaceURI).toBe('http://www.w3.org/2000/svg');
+    });
+    htmlEls.forEach(el => {
+      expect(el.namespaceURI).toBe('http://www.w3.org/1999/xhtml');
+    });
+    mathEls.forEach(el => {
+      expect(el.namespaceURI).toBe('http://www.w3.org/1998/Math/MathML');
     });
 
-    it('should render many portals', () => {
-      var portalContainer1 = document.createElement('div');
-      var portalContainer2 = document.createElement('div');
+    ReactDOM.unmountComponentAtNode(container);
+    expect(container.innerHTML).toBe('');
+  };
 
-      var ops = [];
-      class Child extends React.Component {
-        componentDidMount() {
-          ops.push(`${this.props.name} componentDidMount`);
-        }
-        componentDidUpdate() {
-          ops.push(`${this.props.name} componentDidUpdate`);
-        }
-        componentWillUnmount() {
-          ops.push(`${this.props.name} componentWillUnmount`);
-        }
-        render() {
-          return <div>{this.props.name}</div>;
-        }
+  it('should render one portal', () => {
+    var portalContainer = document.createElement('div');
+
+    ReactDOM.render(
+      <div>
+        {ReactDOM.unstable_createPortal(<div>portal</div>, portalContainer)}
+      </div>,
+      container,
+    );
+    expect(portalContainer.innerHTML).toBe('<div>portal</div>');
+    expect(container.innerHTML).toBe('<div></div>');
+
+    ReactDOM.unmountComponentAtNode(container);
+    expect(portalContainer.innerHTML).toBe('');
+    expect(container.innerHTML).toBe('');
+  });
+
+  it('should render many portals', () => {
+    var portalContainer1 = document.createElement('div');
+    var portalContainer2 = document.createElement('div');
+
+    var ops = [];
+    class Child extends React.Component {
+      componentDidMount() {
+        ops.push(`${this.props.name} componentDidMount`);
       }
+      componentDidUpdate() {
+        ops.push(`${this.props.name} componentDidUpdate`);
+      }
+      componentWillUnmount() {
+        ops.push(`${this.props.name} componentWillUnmount`);
+      }
+      render() {
+        return <div>{this.props.name}</div>;
+      }
+    }
 
-      class Parent extends React.Component {
-        componentDidMount() {
-          ops.push(`Parent:${this.props.step} componentDidMount`);
-        }
-        componentDidUpdate() {
-          ops.push(`Parent:${this.props.step} componentDidUpdate`);
-        }
-        componentWillUnmount() {
-          ops.push(`Parent:${this.props.step} componentWillUnmount`);
-        }
-        render() {
-          const {step} = this.props;
-          return [
-            <Child key="a" name={`normal[0]:${step}`} />,
+    class Parent extends React.Component {
+      componentDidMount() {
+        ops.push(`Parent:${this.props.step} componentDidMount`);
+      }
+      componentDidUpdate() {
+        ops.push(`Parent:${this.props.step} componentDidUpdate`);
+      }
+      componentWillUnmount() {
+        ops.push(`Parent:${this.props.step} componentWillUnmount`);
+      }
+      render() {
+        const {step} = this.props;
+        return [
+          <Child key="a" name={`normal[0]:${step}`} />,
+          ReactDOM.unstable_createPortal(
+            <Child key="b" name={`portal1[0]:${step}`} />,
+            portalContainer1,
+          ),
+          <Child key="c" name={`normal[1]:${step}`} />,
+          ReactDOM.unstable_createPortal(
+            [
+              <Child key="d" name={`portal2[0]:${step}`} />,
+              <Child key="e" name={`portal2[1]:${step}`} />,
+            ],
+            portalContainer2,
+          ),
+        ];
+      }
+    }
+
+    ReactDOM.render(<Parent step="a" />, container);
+    expect(portalContainer1.innerHTML).toBe('<div>portal1[0]:a</div>');
+    expect(portalContainer2.innerHTML).toBe(
+      '<div>portal2[0]:a</div><div>portal2[1]:a</div>',
+    );
+    expect(container.innerHTML).toBe(
+      '<div>normal[0]:a</div><div>normal[1]:a</div>',
+    );
+    expect(ops).toEqual([
+      'normal[0]:a componentDidMount',
+      'portal1[0]:a componentDidMount',
+      'normal[1]:a componentDidMount',
+      'portal2[0]:a componentDidMount',
+      'portal2[1]:a componentDidMount',
+      'Parent:a componentDidMount',
+    ]);
+
+    ops.length = 0;
+    ReactDOM.render(<Parent step="b" />, container);
+    expect(portalContainer1.innerHTML).toBe('<div>portal1[0]:b</div>');
+    expect(portalContainer2.innerHTML).toBe(
+      '<div>portal2[0]:b</div><div>portal2[1]:b</div>',
+    );
+    expect(container.innerHTML).toBe(
+      '<div>normal[0]:b</div><div>normal[1]:b</div>',
+    );
+    expect(ops).toEqual([
+      'normal[0]:b componentDidUpdate',
+      'portal1[0]:b componentDidUpdate',
+      'normal[1]:b componentDidUpdate',
+      'portal2[0]:b componentDidUpdate',
+      'portal2[1]:b componentDidUpdate',
+      'Parent:b componentDidUpdate',
+    ]);
+
+    ops.length = 0;
+    ReactDOM.unmountComponentAtNode(container);
+    expect(portalContainer1.innerHTML).toBe('');
+    expect(portalContainer2.innerHTML).toBe('');
+    expect(container.innerHTML).toBe('');
+    expect(ops).toEqual([
+      'Parent:b componentWillUnmount',
+      'normal[0]:b componentWillUnmount',
+      'portal1[0]:b componentWillUnmount',
+      'normal[1]:b componentWillUnmount',
+      'portal2[0]:b componentWillUnmount',
+      'portal2[1]:b componentWillUnmount',
+    ]);
+  });
+
+  it('should render nested portals', () => {
+    var portalContainer1 = document.createElement('div');
+    var portalContainer2 = document.createElement('div');
+    var portalContainer3 = document.createElement('div');
+
+    ReactDOM.render(
+      [
+        <div key="a">normal[0]</div>,
+        ReactDOM.unstable_createPortal(
+          [
+            <div key="b">portal1[0]</div>,
             ReactDOM.unstable_createPortal(
-              <Child key="b" name={`portal1[0]:${step}`} />,
-              portalContainer1,
+              <div key="c">portal2[0]</div>,
+              portalContainer2,
             ),
-            <Child key="c" name={`normal[1]:${step}`} />,
             ReactDOM.unstable_createPortal(
-              [
-                <Child key="d" name={`portal2[0]:${step}`} />,
-                <Child key="e" name={`portal2[1]:${step}`} />,
-              ],
-              portalContainer2,
+              <div key="d">portal3[0]</div>,
+              portalContainer3,
             ),
-          ];
-        }
-      }
+            <div key="e">portal1[1]</div>,
+          ],
+          portalContainer1,
+        ),
+        <div key="f">normal[1]</div>,
+      ],
+      container,
+    );
+    expect(portalContainer1.innerHTML).toBe(
+      '<div>portal1[0]</div><div>portal1[1]</div>',
+    );
+    expect(portalContainer2.innerHTML).toBe('<div>portal2[0]</div>');
+    expect(portalContainer3.innerHTML).toBe('<div>portal3[0]</div>');
+    expect(container.innerHTML).toBe(
+      '<div>normal[0]</div><div>normal[1]</div>',
+    );
 
-      ReactDOM.render(<Parent step="a" />, container);
-      expect(portalContainer1.innerHTML).toBe('<div>portal1[0]:a</div>');
-      expect(portalContainer2.innerHTML).toBe(
-        '<div>portal2[0]:a</div><div>portal2[1]:a</div>',
-      );
-      expect(container.innerHTML).toBe(
-        '<div>normal[0]:a</div><div>normal[1]:a</div>',
-      );
-      expect(ops).toEqual([
-        'normal[0]:a componentDidMount',
-        'portal1[0]:a componentDidMount',
-        'normal[1]:a componentDidMount',
-        'portal2[0]:a componentDidMount',
-        'portal2[1]:a componentDidMount',
-        'Parent:a componentDidMount',
-      ]);
-
-      ops.length = 0;
-      ReactDOM.render(<Parent step="b" />, container);
-      expect(portalContainer1.innerHTML).toBe('<div>portal1[0]:b</div>');
-      expect(portalContainer2.innerHTML).toBe(
-        '<div>portal2[0]:b</div><div>portal2[1]:b</div>',
-      );
-      expect(container.innerHTML).toBe(
-        '<div>normal[0]:b</div><div>normal[1]:b</div>',
-      );
-      expect(ops).toEqual([
-        'normal[0]:b componentDidUpdate',
-        'portal1[0]:b componentDidUpdate',
-        'normal[1]:b componentDidUpdate',
-        'portal2[0]:b componentDidUpdate',
-        'portal2[1]:b componentDidUpdate',
-        'Parent:b componentDidUpdate',
-      ]);
-
-      ops.length = 0;
-      ReactDOM.unmountComponentAtNode(container);
-      expect(portalContainer1.innerHTML).toBe('');
-      expect(portalContainer2.innerHTML).toBe('');
-      expect(container.innerHTML).toBe('');
-      expect(ops).toEqual([
-        'Parent:b componentWillUnmount',
-        'normal[0]:b componentWillUnmount',
-        'portal1[0]:b componentWillUnmount',
-        'normal[1]:b componentWillUnmount',
-        'portal2[0]:b componentWillUnmount',
-        'portal2[1]:b componentWillUnmount',
-      ]);
-    });
+    ReactDOM.unmountComponentAtNode(container);
+    expect(portalContainer1.innerHTML).toBe('');
+    expect(portalContainer2.innerHTML).toBe('');
+    expect(portalContainer3.innerHTML).toBe('');
+    expect(container.innerHTML).toBe('');
+  });
 
-    it('should render nested portals', () => {
-      var portalContainer1 = document.createElement('div');
-      var portalContainer2 = document.createElement('div');
-      var portalContainer3 = document.createElement('div');
+  it('should reconcile portal children', () => {
+    var portalContainer = document.createElement('div');
 
-      ReactDOM.render(
-        [
-          <div key="a">normal[0]</div>,
-          ReactDOM.unstable_createPortal(
-            [
-              <div key="b">portal1[0]</div>,
-              ReactDOM.unstable_createPortal(
-                <div key="c">portal2[0]</div>,
-                portalContainer2,
-              ),
-              ReactDOM.unstable_createPortal(
-                <div key="d">portal3[0]</div>,
-                portalContainer3,
-              ),
-              <div key="e">portal1[1]</div>,
-            ],
-            portalContainer1,
-          ),
-          <div key="f">normal[1]</div>,
-        ],
-        container,
-      );
-      expect(portalContainer1.innerHTML).toBe(
-        '<div>portal1[0]</div><div>portal1[1]</div>',
-      );
-      expect(portalContainer2.innerHTML).toBe('<div>portal2[0]</div>');
-      expect(portalContainer3.innerHTML).toBe('<div>portal3[0]</div>');
-      expect(container.innerHTML).toBe(
-        '<div>normal[0]</div><div>normal[1]</div>',
-      );
+    ReactDOM.render(
+      <div>
+        {ReactDOM.unstable_createPortal(<div>portal:1</div>, portalContainer)}
+      </div>,
+      container,
+    );
+    expect(portalContainer.innerHTML).toBe('<div>portal:1</div>');
+    expect(container.innerHTML).toBe('<div></div>');
 
-      ReactDOM.unmountComponentAtNode(container);
-      expect(portalContainer1.innerHTML).toBe('');
-      expect(portalContainer2.innerHTML).toBe('');
-      expect(portalContainer3.innerHTML).toBe('');
-      expect(container.innerHTML).toBe('');
-    });
+    ReactDOM.render(
+      <div>
+        {ReactDOM.unstable_createPortal(<div>portal:2</div>, portalContainer)}
+      </div>,
+      container,
+    );
+    expect(portalContainer.innerHTML).toBe('<div>portal:2</div>');
+    expect(container.innerHTML).toBe('<div></div>');
 
-    it('should reconcile portal children', () => {
-      var portalContainer = document.createElement('div');
+    ReactDOM.render(
+      <div>
+        {ReactDOM.unstable_createPortal(<p>portal:3</p>, portalContainer)}
+      </div>,
+      container,
+    );
+    expect(portalContainer.innerHTML).toBe('<p>portal:3</p>');
+    expect(container.innerHTML).toBe('<div></div>');
 
-      ReactDOM.render(
-        <div>
-          {ReactDOM.unstable_createPortal(<div>portal:1</div>, portalContainer)}
-        </div>,
-        container,
-      );
-      expect(portalContainer.innerHTML).toBe('<div>portal:1</div>');
-      expect(container.innerHTML).toBe('<div></div>');
-
-      ReactDOM.render(
-        <div>
-          {ReactDOM.unstable_createPortal(<div>portal:2</div>, portalContainer)}
-        </div>,
-        container,
-      );
-      expect(portalContainer.innerHTML).toBe('<div>portal:2</div>');
-      expect(container.innerHTML).toBe('<div></div>');
-
-      ReactDOM.render(
-        <div>
-          {ReactDOM.unstable_createPortal(<p>portal:3</p>, portalContainer)}
-        </div>,
-        container,
-      );
-      expect(portalContainer.innerHTML).toBe('<p>portal:3</p>');
-      expect(container.innerHTML).toBe('<div></div>');
-
-      ReactDOM.render(
-        <div>
-          {ReactDOM.unstable_createPortal(['Hi', 'Bye'], portalContainer)}
-        </div>,
-        container,
-      );
-      expect(portalContainer.innerHTML).toBe('HiBye');
-      expect(container.innerHTML).toBe('<div></div>');
-
-      ReactDOM.render(
-        <div>
-          {ReactDOM.unstable_createPortal(['Bye', 'Hi'], portalContainer)}
-        </div>,
-        container,
-      );
-      expect(portalContainer.innerHTML).toBe('ByeHi');
-      expect(container.innerHTML).toBe('<div></div>');
-
-      ReactDOM.render(
-        <div>
-          {ReactDOM.unstable_createPortal(null, portalContainer)}
-        </div>,
-        container,
-      );
-      expect(portalContainer.innerHTML).toBe('');
-      expect(container.innerHTML).toBe('<div></div>');
-    });
+    ReactDOM.render(
+      <div>
+        {ReactDOM.unstable_createPortal(['Hi', 'Bye'], portalContainer)}
+      </div>,
+      container,
+    );
+    expect(portalContainer.innerHTML).toBe('HiBye');
+    expect(container.innerHTML).toBe('<div></div>');
 
-    it('should keep track of namespace across portals (simple)', () => {
-      assertNamespacesMatch(
-        <svg {...expectSVG}>
-          <image {...expectSVG} />
-          {usePortal(<div {...expectHTML} />)}
-          <image {...expectSVG} />
-        </svg>,
-      );
-      assertNamespacesMatch(
-        <math {...expectMath}>
-          <mi {...expectMath} />
-          {usePortal(<div {...expectHTML} />)}
-          <mi {...expectMath} />
-        </math>,
-      );
-      assertNamespacesMatch(
-        <div {...expectHTML}>
-          <p {...expectHTML} />
-          {usePortal(
-            <svg {...expectSVG}>
-              <image {...expectSVG} />
-            </svg>,
-          )}
-          <p {...expectHTML} />
-        </div>,
-      );
-    });
+    ReactDOM.render(
+      <div>
+        {ReactDOM.unstable_createPortal(['Bye', 'Hi'], portalContainer)}
+      </div>,
+      container,
+    );
+    expect(portalContainer.innerHTML).toBe('ByeHi');
+    expect(container.innerHTML).toBe('<div></div>');
 
-    it('should keep track of namespace across portals (medium)', () => {
-      assertNamespacesMatch(
-        <svg {...expectSVG}>
-          <image {...expectSVG} />
-          {usePortal(<div {...expectHTML} />)}
-          <image {...expectSVG} />
-          {usePortal(<div {...expectHTML} />)}
-          <image {...expectSVG} />
-        </svg>,
-      );
-      assertNamespacesMatch(
-        <div {...expectHTML}>
-          <math {...expectMath}>
-            <mi {...expectMath} />
-            {usePortal(
-              <svg {...expectSVG}>
-                <image {...expectSVG} />
-              </svg>,
-            )}
-          </math>
-          <p {...expectHTML} />
-        </div>,
-      );
-      assertNamespacesMatch(
+    ReactDOM.render(
+      <div>
+        {ReactDOM.unstable_createPortal(null, portalContainer)}
+      </div>,
+      container,
+    );
+    expect(portalContainer.innerHTML).toBe('');
+    expect(container.innerHTML).toBe('<div></div>');
+  });
+
+  it('should keep track of namespace across portals (simple)', () => {
+    assertNamespacesMatch(
+      <svg {...expectSVG}>
+        <image {...expectSVG} />
+        {usePortal(<div {...expectHTML} />)}
+        <image {...expectSVG} />
+      </svg>,
+    );
+    assertNamespacesMatch(
+      <math {...expectMath}>
+        <mi {...expectMath} />
+        {usePortal(<div {...expectHTML} />)}
+        <mi {...expectMath} />
+      </math>,
+    );
+    assertNamespacesMatch(
+      <div {...expectHTML}>
+        <p {...expectHTML} />
+        {usePortal(
+          <svg {...expectSVG}>
+            <image {...expectSVG} />
+          </svg>,
+        )}
+        <p {...expectHTML} />
+      </div>,
+    );
+  });
+
+  it('should keep track of namespace across portals (medium)', () => {
+    assertNamespacesMatch(
+      <svg {...expectSVG}>
+        <image {...expectSVG} />
+        {usePortal(<div {...expectHTML} />)}
+        <image {...expectSVG} />
+        {usePortal(<div {...expectHTML} />)}
+        <image {...expectSVG} />
+      </svg>,
+    );
+    assertNamespacesMatch(
+      <div {...expectHTML}>
         <math {...expectMath}>
           <mi {...expectMath} />
           {usePortal(
             <svg {...expectSVG}>
               <image {...expectSVG} />
-              <foreignObject {...expectSVG}>
-                <p {...expectHTML} />
-                <math {...expectMath}>
-                  <mi {...expectMath} />
-                </math>
-                <p {...expectHTML} />
-              </foreignObject>
-              <image {...expectSVG} />
-            </svg>,
-          )}
-          <mi {...expectMath} />
-        </math>,
-      );
-      assertNamespacesMatch(
-        <div {...expectHTML}>
-          {usePortal(
-            <svg {...expectSVG}>
-              {usePortal(<div {...expectHTML} />)}
-              <image {...expectSVG} />
             </svg>,
           )}
-          <p {...expectHTML} />
-        </div>,
-      );
-      assertNamespacesMatch(
-        <svg {...expectSVG}>
+        </math>
+        <p {...expectHTML} />
+      </div>,
+    );
+    assertNamespacesMatch(
+      <math {...expectMath}>
+        <mi {...expectMath} />
+        {usePortal(
+          <svg {...expectSVG}>
+            <image {...expectSVG} />
+            <foreignObject {...expectSVG}>
+              <p {...expectHTML} />
+              <math {...expectMath}>
+                <mi {...expectMath} />
+              </math>
+              <p {...expectHTML} />
+            </foreignObject>
+            <image {...expectSVG} />
+          </svg>,
+        )}
+        <mi {...expectMath} />
+      </math>,
+    );
+    assertNamespacesMatch(
+      <div {...expectHTML}>
+        {usePortal(
           <svg {...expectSVG}>
             {usePortal(<div {...expectHTML} />)}
             <image {...expectSVG} />
-          </svg>
+          </svg>,
+        )}
+        <p {...expectHTML} />
+      </div>,
+    );
+    assertNamespacesMatch(
+      <svg {...expectSVG}>
+        <svg {...expectSVG}>
+          {usePortal(<div {...expectHTML} />)}
           <image {...expectSVG} />
-        </svg>,
-      );
-    });
+        </svg>
+        <image {...expectSVG} />
+      </svg>,
+    );
+  });
 
-    it('should keep track of namespace across portals (complex)', () => {
-      assertNamespacesMatch(
-        <div {...expectHTML}>
-          {usePortal(
-            <svg {...expectSVG}>
-              <image {...expectSVG} />
-            </svg>,
-          )}
-          <p {...expectHTML} />
+  it('should keep track of namespace across portals (complex)', () => {
+    assertNamespacesMatch(
+      <div {...expectHTML}>
+        {usePortal(
           <svg {...expectSVG}>
             <image {...expectSVG} />
-          </svg>
+          </svg>,
+        )}
+        <p {...expectHTML} />
+        <svg {...expectSVG}>
+          <image {...expectSVG} />
+        </svg>
+        <svg {...expectSVG}>
           <svg {...expectSVG}>
-            <svg {...expectSVG}>
-              <image {...expectSVG} />
-            </svg>
             <image {...expectSVG} />
           </svg>
-          <p {...expectHTML} />
-        </div>,
-      );
-      assertNamespacesMatch(
-        <div {...expectHTML}>
+          <image {...expectSVG} />
+        </svg>
+        <p {...expectHTML} />
+      </div>,
+    );
+    assertNamespacesMatch(
+      <div {...expectHTML}>
+        <svg {...expectSVG}>
           <svg {...expectSVG}>
-            <svg {...expectSVG}>
-              <image {...expectSVG} />
-              {usePortal(
+            <image {...expectSVG} />
+            {usePortal(
+              <svg {...expectSVG}>
+                <image {...expectSVG} />
                 <svg {...expectSVG}>
                   <image {...expectSVG} />
-                  <svg {...expectSVG}>
-                    <image {...expectSVG} />
-                  </svg>
-                  <image {...expectSVG} />
-                </svg>,
-              )}
-              <image {...expectSVG} />
-              <foreignObject {...expectSVG}>
-                <p {...expectHTML} />
-                {usePortal(<p {...expectHTML} />)}
-                <p {...expectHTML} />
-              </foreignObject>
-            </svg>
+                </svg>
+                <image {...expectSVG} />
+              </svg>,
+            )}
             <image {...expectSVG} />
-          </svg>
-          <p {...expectHTML} />
-        </div>,
-      );
-      assertNamespacesMatch(
-        <div {...expectHTML}>
-          <svg {...expectSVG}>
             <foreignObject {...expectSVG}>
               <p {...expectHTML} />
-              {usePortal(
-                <svg {...expectSVG}>
-                  <image {...expectSVG} />
-                  <svg {...expectSVG}>
-                    <image {...expectSVG} />
-                    <foreignObject {...expectSVG}>
-                      <p {...expectHTML} />
-                    </foreignObject>
-                    {usePortal(<p {...expectHTML} />)}
-                  </svg>
-                  <image {...expectSVG} />
-                </svg>,
-              )}
+              {usePortal(<p {...expectHTML} />)}
               <p {...expectHTML} />
             </foreignObject>
-            <image {...expectSVG} />
           </svg>
-          <p {...expectHTML} />
-        </div>,
-      );
-    });
-
-    it('should unwind namespaces on uncaught errors', () => {
-      function BrokenRender() {
-        throw new Error('Hello');
-      }
-
-      expect(() => {
-        assertNamespacesMatch(
-          <svg {...expectSVG}>
-            <BrokenRender />
-          </svg>,
-        );
-      }).toThrow('Hello');
-      assertNamespacesMatch(<div {...expectHTML} />);
-    });
-
-    it('should unwind namespaces on caught errors', () => {
-      function BrokenRender() {
-        throw new Error('Hello');
-      }
-
-      class ErrorBoundary extends React.Component {
-        state = {error: null};
-        componentDidCatch(error) {
-          this.setState({error});
-        }
-        render() {
-          if (this.state.error) {
-            return <p {...expectHTML} />;
-          }
-          return this.props.children;
-        }
-      }
-
-      assertNamespacesMatch(
+          <image {...expectSVG} />
+        </svg>
+        <p {...expectHTML} />
+      </div>,
+    );
+    assertNamespacesMatch(
+      <div {...expectHTML}>
         <svg {...expectSVG}>
           <foreignObject {...expectSVG}>
-            <ErrorBoundary>
-              <math {...expectMath}>
-                <BrokenRender />
-              </math>
-            </ErrorBoundary>
+            <p {...expectHTML} />
+            {usePortal(
+              <svg {...expectSVG}>
+                <image {...expectSVG} />
+                <svg {...expectSVG}>
+                  <image {...expectSVG} />
+                  <foreignObject {...expectSVG}>
+                    <p {...expectHTML} />
+                  </foreignObject>
+                  {usePortal(<p {...expectHTML} />)}
+                </svg>
+                <image {...expectSVG} />
+              </svg>,
+            )}
+            <p {...expectHTML} />
           </foreignObject>
           <image {...expectSVG} />
+        </svg>
+        <p {...expectHTML} />
+      </div>,
+    );
+  });
+
+  it('should unwind namespaces on uncaught errors', () => {
+    function BrokenRender() {
+      throw new Error('Hello');
+    }
+
+    expect(() => {
+      assertNamespacesMatch(
+        <svg {...expectSVG}>
+          <BrokenRender />
         </svg>,
       );
-      assertNamespacesMatch(<div {...expectHTML} />);
-    });
+    }).toThrow('Hello');
+    assertNamespacesMatch(<div {...expectHTML} />);
+  });
 
-    it('should unwind namespaces on caught errors in a portal', () => {
-      function BrokenRender() {
-        throw new Error('Hello');
-      }
+  it('should unwind namespaces on caught errors', () => {
+    function BrokenRender() {
+      throw new Error('Hello');
+    }
 
-      class ErrorBoundary extends React.Component {
-        state = {error: null};
-        componentDidCatch(error) {
-          this.setState({error});
-        }
-        render() {
-          if (this.state.error) {
-            return <image {...expectSVG} />;
-          }
-          return this.props.children;
+    class ErrorBoundary extends React.Component {
+      state = {error: null};
+      componentDidCatch(error) {
+        this.setState({error});
+      }
+      render() {
+        if (this.state.error) {
+          return <p {...expectHTML} />;
         }
+        return this.props.children;
       }
+    }
 
-      assertNamespacesMatch(
-        <svg {...expectSVG}>
+    assertNamespacesMatch(
+      <svg {...expectSVG}>
+        <foreignObject {...expectSVG}>
           <ErrorBoundary>
-            {usePortal(
-              <div {...expectHTML}>
-                <math {...expectMath}>
-                  <BrokenRender />)
-                </math>
-              </div>,
-            )}
+            <math {...expectMath}>
+              <BrokenRender />
+            </math>
           </ErrorBoundary>
-          {usePortal(<div {...expectHTML} />)}
-        </svg>,
-      );
-    });
-
-    it('should pass portal context when rendering subtree elsewhere', () => {
-      var portalContainer = document.createElement('div');
+        </foreignObject>
+        <image {...expectSVG} />
+      </svg>,
+    );
+    assertNamespacesMatch(<div {...expectHTML} />);
+  });
 
-      class Component extends React.Component {
-        static contextTypes = {
-          foo: PropTypes.string.isRequired,
-        };
+  it('should unwind namespaces on caught errors in a portal', () => {
+    function BrokenRender() {
+      throw new Error('Hello');
+    }
 
-        render() {
-          return <div>{this.context.foo}</div>;
+    class ErrorBoundary extends React.Component {
+      state = {error: null};
+      componentDidCatch(error) {
+        this.setState({error});
+      }
+      render() {
+        if (this.state.error) {
+          return <image {...expectSVG} />;
         }
+        return this.props.children;
       }
+    }
 
-      class Parent extends React.Component {
-        static childContextTypes = {
-          foo: PropTypes.string.isRequired,
-        };
+    assertNamespacesMatch(
+      <svg {...expectSVG}>
+        <ErrorBoundary>
+          {usePortal(
+            <div {...expectHTML}>
+              <math {...expectMath}>
+                <BrokenRender />)
+              </math>
+            </div>,
+          )}
+        </ErrorBoundary>
+        {usePortal(<div {...expectHTML} />)}
+      </svg>,
+    );
+  });
 
-        getChildContext() {
-          return {
-            foo: 'bar',
-          };
-        }
+  it('should pass portal context when rendering subtree elsewhere', () => {
+    var portalContainer = document.createElement('div');
 
-        render() {
-          return ReactDOM.unstable_createPortal(<Component />, portalContainer);
-        }
-      }
+    class Component extends React.Component {
+      static contextTypes = {
+        foo: PropTypes.string.isRequired,
+      };
 
-      ReactDOM.render(<Parent />, container);
-      expect(container.innerHTML).toBe('');
-      expect(portalContainer.innerHTML).toBe('<div>bar</div>');
-    });
+      render() {
+        return <div>{this.context.foo}</div>;
+      }
+    }
 
-    it('should update portal context if it changes due to setState', () => {
-      var portalContainer = document.createElement('div');
+    class Parent extends React.Component {
+      static childContextTypes = {
+        foo: PropTypes.string.isRequired,
+      };
 
-      class Component extends React.Component {
-        static contextTypes = {
-          foo: PropTypes.string.isRequired,
-          getFoo: PropTypes.func.isRequired,
+      getChildContext() {
+        return {
+          foo: 'bar',
         };
+      }
 
-        render() {
-          return <div>{this.context.foo + '-' + this.context.getFoo()}</div>;
-        }
+      render() {
+        return ReactDOM.unstable_createPortal(<Component />, portalContainer);
       }
+    }
 
-      class Parent extends React.Component {
-        static childContextTypes = {
-          foo: PropTypes.string.isRequired,
-          getFoo: PropTypes.func.isRequired,
-        };
+    ReactDOM.render(<Parent />, container);
+    expect(container.innerHTML).toBe('');
+    expect(portalContainer.innerHTML).toBe('<div>bar</div>');
+  });
 
-        state = {
-          bar: 'initial',
-        };
+  it('should update portal context if it changes due to setState', () => {
+    var portalContainer = document.createElement('div');
 
-        getChildContext() {
-          return {
-            foo: this.state.bar,
-            getFoo: () => this.state.bar,
-          };
-        }
+    class Component extends React.Component {
+      static contextTypes = {
+        foo: PropTypes.string.isRequired,
+        getFoo: PropTypes.func.isRequired,
+      };
 
-        render() {
-          return ReactDOM.unstable_createPortal(<Component />, portalContainer);
-        }
+      render() {
+        return <div>{this.context.foo + '-' + this.context.getFoo()}</div>;
       }
+    }
 
-      var instance = ReactDOM.render(<Parent />, container);
-      expect(portalContainer.innerHTML).toBe('<div>initial-initial</div>');
-      expect(container.innerHTML).toBe('');
-      instance.setState({bar: 'changed'});
-      expect(portalContainer.innerHTML).toBe('<div>changed-changed</div>');
-      expect(container.innerHTML).toBe('');
-    });
+    class Parent extends React.Component {
+      static childContextTypes = {
+        foo: PropTypes.string.isRequired,
+        getFoo: PropTypes.func.isRequired,
+      };
 
-    it('should update portal context if it changes due to re-render', () => {
-      var portalContainer = document.createElement('div');
+      state = {
+        bar: 'initial',
+      };
 
-      class Component extends React.Component {
-        static contextTypes = {
-          foo: PropTypes.string.isRequired,
-          getFoo: PropTypes.func.isRequired,
+      getChildContext() {
+        return {
+          foo: this.state.bar,
+          getFoo: () => this.state.bar,
         };
+      }
 
-        render() {
-          return <div>{this.context.foo + '-' + this.context.getFoo()}</div>;
-        }
+      render() {
+        return ReactDOM.unstable_createPortal(<Component />, portalContainer);
       }
+    }
 
-      class Parent extends React.Component {
-        static childContextTypes = {
-          foo: PropTypes.string.isRequired,
-          getFoo: PropTypes.func.isRequired,
-        };
+    var instance = ReactDOM.render(<Parent />, container);
+    expect(portalContainer.innerHTML).toBe('<div>initial-initial</div>');
+    expect(container.innerHTML).toBe('');
+    instance.setState({bar: 'changed'});
+    expect(portalContainer.innerHTML).toBe('<div>changed-changed</div>');
+    expect(container.innerHTML).toBe('');
+  });
 
-        getChildContext() {
-          return {
-            foo: this.props.bar,
-            getFoo: () => this.props.bar,
-          };
-        }
+  it('should update portal context if it changes due to re-render', () => {
+    var portalContainer = document.createElement('div');
 
-        render() {
-          return ReactDOM.unstable_createPortal(<Component />, portalContainer);
-        }
+    class Component extends React.Component {
+      static contextTypes = {
+        foo: PropTypes.string.isRequired,
+        getFoo: PropTypes.func.isRequired,
+      };
+
+      render() {
+        return <div>{this.context.foo + '-' + this.context.getFoo()}</div>;
       }
+    }
 
-      ReactDOM.render(<Parent bar="initial" />, container);
-      expect(portalContainer.innerHTML).toBe('<div>initial-initial</div>');
-      expect(container.innerHTML).toBe('');
-      ReactDOM.render(<Parent bar="changed" />, container);
-      expect(portalContainer.innerHTML).toBe('<div>changed-changed</div>');
-      expect(container.innerHTML).toBe('');
-    });
+    class Parent extends React.Component {
+      static childContextTypes = {
+        foo: PropTypes.string.isRequired,
+        getFoo: PropTypes.func.isRequired,
+      };
 
-    it('findDOMNode should find dom element after expanding a fragment', () => {
-      class MyNode extends React.Component {
-        render() {
-          return !this.props.flag
-            ? [<div key="a" />]
-            : [<span key="b" />, <div key="a" />];
-        }
+      getChildContext() {
+        return {
+          foo: this.props.bar,
+          getFoo: () => this.props.bar,
+        };
       }
 
-      var myNodeA = ReactDOM.render(<MyNode />, container);
-      var a = ReactDOM.findDOMNode(myNodeA);
-      expect(a.tagName).toBe('DIV');
+      render() {
+        return ReactDOM.unstable_createPortal(<Component />, portalContainer);
+      }
+    }
 
-      var myNodeB = ReactDOM.render(<MyNode flag={true} />, container);
-      expect(myNodeA === myNodeB).toBe(true);
+    ReactDOM.render(<Parent bar="initial" />, container);
+    expect(portalContainer.innerHTML).toBe('<div>initial-initial</div>');
+    expect(container.innerHTML).toBe('');
+    ReactDOM.render(<Parent bar="changed" />, container);
+    expect(portalContainer.innerHTML).toBe('<div>changed-changed</div>');
+    expect(container.innerHTML).toBe('');
+  });
 
-      var b = ReactDOM.findDOMNode(myNodeB);
-      expect(b.tagName).toBe('SPAN');
-    });
+  it('findDOMNode should find dom element after expanding a fragment', () => {
+    class MyNode extends React.Component {
+      render() {
+        return !this.props.flag
+          ? [<div key="a" />]
+          : [<span key="b" />, <div key="a" />];
+      }
+    }
 
-    it('should bubble events from the portal to the parent', () => {
-      var portalContainer = document.createElement('div');
+    var myNodeA = ReactDOM.render(<MyNode />, container);
+    var a = ReactDOM.findDOMNode(myNodeA);
+    expect(a.tagName).toBe('DIV');
 
-      var ops = [];
-      var portal = null;
+    var myNodeB = ReactDOM.render(<MyNode flag={true} />, container);
+    expect(myNodeA === myNodeB).toBe(true);
 
-      ReactDOM.render(
-        <div onClick={() => ops.push('parent clicked')}>
-          {ReactDOM.unstable_createPortal(
-            <div
-              onClick={() => ops.push('portal clicked')}
-              ref={n => (portal = n)}>
-              portal
-            </div>,
-            portalContainer,
-          )}
-        </div>,
-        container,
-      );
+    var b = ReactDOM.findDOMNode(myNodeB);
+    expect(b.tagName).toBe('SPAN');
+  });
 
-      expect(portal.tagName).toBe('DIV');
+  it('should bubble events from the portal to the parent', () => {
+    var portalContainer = document.createElement('div');
 
-      var fakeNativeEvent = {};
-      ReactTestUtils.simulateNativeEventOnNode(
-        'topClick',
-        portal,
-        fakeNativeEvent,
-      );
+    var ops = [];
+    var portal = null;
 
-      expect(ops).toEqual(['portal clicked', 'parent clicked']);
-    });
+    ReactDOM.render(
+      <div onClick={() => ops.push('parent clicked')}>
+        {ReactDOM.unstable_createPortal(
+          <div
+            onClick={() => ops.push('portal clicked')}
+            ref={n => (portal = n)}>
+            portal
+          </div>,
+          portalContainer,
+        )}
+      </div>,
+      container,
+    );
 
-    it('should not onMouseLeave when staying in the portal', () => {
-      var portalContainer = document.createElement('div');
+    expect(portal.tagName).toBe('DIV');
 
-      var ops = [];
-      var firstTarget = null;
-      var secondTarget = null;
-      var thirdTarget = null;
+    var fakeNativeEvent = {};
+    ReactTestUtils.simulateNativeEventOnNode(
+      'topClick',
+      portal,
+      fakeNativeEvent,
+    );
 
-      function simulateMouseMove(from, to) {
-        if (from) {
-          ReactTestUtils.simulateNativeEventOnNode('topMouseOut', from, {
-            target: from,
-            relatedTarget: to,
-          });
-        }
-        if (to) {
-          ReactTestUtils.simulateNativeEventOnNode('topMouseOver', to, {
-            target: to,
-            relatedTarget: from,
-          });
-        }
+    expect(ops).toEqual(['portal clicked', 'parent clicked']);
+  });
+
+  it('should not onMouseLeave when staying in the portal', () => {
+    var portalContainer = document.createElement('div');
+
+    var ops = [];
+    var firstTarget = null;
+    var secondTarget = null;
+    var thirdTarget = null;
+
+    function simulateMouseMove(from, to) {
+      if (from) {
+        ReactTestUtils.simulateNativeEventOnNode('topMouseOut', from, {
+          target: from,
+          relatedTarget: to,
+        });
+      }
+      if (to) {
+        ReactTestUtils.simulateNativeEventOnNode('topMouseOver', to, {
+          target: to,
+          relatedTarget: from,
+        });
       }
+    }
 
-      ReactDOM.render(
-        <div>
-          <div
-            onMouseEnter={() => ops.push('enter parent')}
-            onMouseLeave={() => ops.push('leave parent')}>
-            <div ref={n => (firstTarget = n)} />
-            {ReactDOM.unstable_createPortal(
-              <div
-                onMouseEnter={() => ops.push('enter portal')}
-                onMouseLeave={() => ops.push('leave portal')}
-                ref={n => (secondTarget = n)}>
-                portal
-              </div>,
-              portalContainer,
-            )}
-          </div>
-          <div ref={n => (thirdTarget = n)} />
-        </div>,
-        container,
-      );
+    ReactDOM.render(
+      <div>
+        <div
+          onMouseEnter={() => ops.push('enter parent')}
+          onMouseLeave={() => ops.push('leave parent')}>
+          <div ref={n => (firstTarget = n)} />
+          {ReactDOM.unstable_createPortal(
+            <div
+              onMouseEnter={() => ops.push('enter portal')}
+              onMouseLeave={() => ops.push('leave portal')}
+              ref={n => (secondTarget = n)}>
+              portal
+            </div>,
+            portalContainer,
+          )}
+        </div>
+        <div ref={n => (thirdTarget = n)} />
+      </div>,
+      container,
+    );
 
-      simulateMouseMove(null, firstTarget);
-      expect(ops).toEqual(['enter parent']);
+    simulateMouseMove(null, firstTarget);
+    expect(ops).toEqual(['enter parent']);
 
-      ops = [];
+    ops = [];
 
-      simulateMouseMove(firstTarget, secondTarget);
-      expect(ops).toEqual([
-        // Parent did not invoke leave because we're still inside the portal.
-        'enter portal',
-      ]);
+    simulateMouseMove(firstTarget, secondTarget);
+    expect(ops).toEqual([
+      // Parent did not invoke leave because we're still inside the portal.
+      'enter portal',
+    ]);
 
-      ops = [];
+    ops = [];
 
-      simulateMouseMove(secondTarget, thirdTarget);
-      expect(ops).toEqual([
-        'leave portal',
-        'leave parent', // Only when we leave the portal does onMouseLeave fire.
-      ]);
-    });
+    simulateMouseMove(secondTarget, thirdTarget);
+    expect(ops).toEqual([
+      'leave portal',
+      'leave parent', // Only when we leave the portal does onMouseLeave fire.
+    ]);
+  });
 
-    it('should warn for non-functional event listeners', () => {
-      spyOn(console, 'error');
-      class Example extends React.Component {
-        render() {
-          return <div onClick="woops" />;
-        }
+  it('should warn for non-functional event listeners', () => {
+    spyOn(console, 'error');
+    class Example extends React.Component {
+      render() {
+        return <div onClick="woops" />;
       }
-      ReactDOM.render(<Example />, container);
-      expectDev(console.error.calls.count()).toBe(1);
-      expectDev(
-        normalizeCodeLocInfo(console.error.calls.argsFor(0)[0]),
-      ).toContain(
-        'Expected `onClick` listener to be a function, instead got a value of `string` type.\n' +
-          '    in div (at **)\n' +
-          '    in Example (at **)',
-      );
-    });
+    }
+    ReactDOM.render(<Example />, container);
+    expectDev(console.error.calls.count()).toBe(1);
+    expectDev(
+      normalizeCodeLocInfo(console.error.calls.argsFor(0)[0]),
+    ).toContain(
+      'Expected `onClick` listener to be a function, instead got a value of `string` type.\n' +
+        '    in div (at **)\n' +
+        '    in Example (at **)',
+    );
+  });
 
-    it('should not update event handlers until commit', () => {
-      let ops = [];
-      const handlerA = () => ops.push('A');
-      const handlerB = () => ops.push('B');
+  it('should not update event handlers until commit', () => {
+    let ops = [];
+    const handlerA = () => ops.push('A');
+    const handlerB = () => ops.push('B');
 
-      class Example extends React.Component {
-        state = {flip: false, count: 0};
-        flip() {
-          this.setState({flip: true, count: this.state.count + 1});
-        }
-        tick() {
-          this.setState({count: this.state.count + 1});
-        }
-        render() {
-          const useB = !this.props.forceA && this.state.flip;
-          return <div onClick={useB ? handlerB : handlerA} />;
-        }
+    class Example extends React.Component {
+      state = {flip: false, count: 0};
+      flip() {
+        this.setState({flip: true, count: this.state.count + 1});
       }
-
-      class Click extends React.Component {
-        constructor() {
-          super();
-          click(node);
-        }
-        render() {
-          return null;
-        }
+      tick() {
+        this.setState({count: this.state.count + 1});
+      }
+      render() {
+        const useB = !this.props.forceA && this.state.flip;
+        return <div onClick={useB ? handlerB : handlerA} />;
       }
+    }
 
-      let inst;
-      ReactDOM.render([<Example key="a" ref={n => (inst = n)} />], container);
-      const node = container.firstChild;
-      expect(node.tagName).toEqual('DIV');
-
-      function click(target) {
-        var fakeNativeEvent = {};
-        ReactTestUtils.simulateNativeEventOnNode(
-          'topClick',
-          target,
-          fakeNativeEvent,
-        );
+    class Click extends React.Component {
+      constructor() {
+        super();
+        click(node);
+      }
+      render() {
+        return null;
       }
+    }
 
-      click(node);
+    let inst;
+    ReactDOM.render([<Example key="a" ref={n => (inst = n)} />], container);
+    const node = container.firstChild;
+    expect(node.tagName).toEqual('DIV');
 
-      expect(ops).toEqual(['A']);
-      ops = [];
+    function click(target) {
+      var fakeNativeEvent = {};
+      ReactTestUtils.simulateNativeEventOnNode(
+        'topClick',
+        target,
+        fakeNativeEvent,
+      );
+    }
 
-      // Render with the other event handler.
-      inst.flip();
+    click(node);
 
-      click(node);
+    expect(ops).toEqual(['A']);
+    ops = [];
 
-      expect(ops).toEqual(['B']);
-      ops = [];
+    // Render with the other event handler.
+    inst.flip();
 
-      // Rerender without changing any props.
-      inst.tick();
+    click(node);
 
-      click(node);
+    expect(ops).toEqual(['B']);
+    ops = [];
 
-      expect(ops).toEqual(['B']);
-      ops = [];
+    // Rerender without changing any props.
+    inst.tick();
 
-      // Render a flip back to the A handler. The second component invokes the
-      // click handler during render to simulate a click during an aborted
-      // render. I use this hack because at current time we don't have a way to
-      // test aborted ReactDOM renders.
-      ReactDOM.render(
-        [<Example key="a" forceA={true} />, <Click key="b" />],
-        container,
-      );
+    click(node);
 
-      // Because the new click handler has not yet committed, we should still
-      // invoke B.
-      expect(ops).toEqual(['B']);
-      ops = [];
+    expect(ops).toEqual(['B']);
+    ops = [];
 
-      // Any click that happens after commit, should invoke A.
-      click(node);
-      expect(ops).toEqual(['A']);
-    });
+    // Render a flip back to the A handler. The second component invokes the
+    // click handler during render to simulate a click during an aborted
+    // render. I use this hack because at current time we don't have a way to
+    // test aborted ReactDOM renders.
+    ReactDOM.render(
+      [<Example key="a" forceA={true} />, <Click key="b" />],
+      container,
+    );
 
-    it('should not crash encountering low-priority tree', () => {
-      ReactDOM.render(
-        <div hidden={true}>
-          <div />
-        </div>,
-        container,
-      );
-    });
+    // Because the new click handler has not yet committed, we should still
+    // invoke B.
+    expect(ops).toEqual(['B']);
+    ops = [];
 
-    it('should not warn when rendering into an empty container', () => {
-      spyOn(console, 'error');
-      ReactDOM.render(<div>foo</div>, container);
-      expect(container.innerHTML).toBe('<div>foo</div>');
-      ReactDOM.render(null, container);
-      expect(container.innerHTML).toBe('');
-      expectDev(console.error.calls.count()).toBe(0);
-      ReactDOM.render(<div>bar</div>, container);
-      expect(container.innerHTML).toBe('<div>bar</div>');
-      expectDev(console.error.calls.count()).toBe(0);
-    });
+    // Any click that happens after commit, should invoke A.
+    click(node);
+    expect(ops).toEqual(['A']);
+  });
 
-    it('should warn when replacing a container which was manually updated outside of React', () => {
-      spyOn(console, 'error');
-      // when not messing with the DOM outside of React
-      ReactDOM.render(<div key="1">foo</div>, container);
-      ReactDOM.render(<div key="1">bar</div>, container);
-      expect(container.innerHTML).toBe('<div>bar</div>');
-      // then we mess with the DOM before an update
-      // we know this will error - that is expected right now
-      // It's an error of type 'NotFoundError' with no message
-      expect(() => {
-        container.innerHTML = '<div>MEOW.</div>';
-        ReactDOM.render(<div key="2">baz</div>, container);
-      }).toThrowError();
-      expectDev(console.error.calls.count()).toBe(1);
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'render(...): ' +
-          'It looks like the React-rendered content of this container was ' +
-          'removed without using React. This is not supported and will ' +
-          'cause errors. Instead, call ReactDOM.unmountComponentAtNode ' +
-          'to empty a container.',
-      );
-    });
+  it('should not crash encountering low-priority tree', () => {
+    ReactDOM.render(
+      <div hidden={true}>
+        <div />
+      </div>,
+      container,
+    );
+  });
 
-    it('should warn when doing an update to a container manually updated outside of React', () => {
-      spyOn(console, 'error');
-      // when not messing with the DOM outside of React
-      ReactDOM.render(<div>foo</div>, container);
-      ReactDOM.render(<div>bar</div>, container);
-      expect(container.innerHTML).toBe('<div>bar</div>');
-      // then we mess with the DOM before an update
+  it('should not warn when rendering into an empty container', () => {
+    spyOn(console, 'error');
+    ReactDOM.render(<div>foo</div>, container);
+    expect(container.innerHTML).toBe('<div>foo</div>');
+    ReactDOM.render(null, container);
+    expect(container.innerHTML).toBe('');
+    expectDev(console.error.calls.count()).toBe(0);
+    ReactDOM.render(<div>bar</div>, container);
+    expect(container.innerHTML).toBe('<div>bar</div>');
+    expectDev(console.error.calls.count()).toBe(0);
+  });
+
+  it('should warn when replacing a container which was manually updated outside of React', () => {
+    spyOn(console, 'error');
+    // when not messing with the DOM outside of React
+    ReactDOM.render(<div key="1">foo</div>, container);
+    ReactDOM.render(<div key="1">bar</div>, container);
+    expect(container.innerHTML).toBe('<div>bar</div>');
+    // then we mess with the DOM before an update
+    // we know this will error - that is expected right now
+    // It's an error of type 'NotFoundError' with no message
+    expect(() => {
       container.innerHTML = '<div>MEOW.</div>';
-      ReactDOM.render(<div>baz</div>, container);
-      // silently fails to update
-      expectDev(console.error.calls.count()).toBe(1);
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'render(...): ' +
-          'It looks like the React-rendered content of this container was ' +
-          'removed without using React. This is not supported and will ' +
-          'cause errors. Instead, call ReactDOM.unmountComponentAtNode ' +
-          'to empty a container.',
-      );
-    });
+      ReactDOM.render(<div key="2">baz</div>, container);
+    }).toThrowError();
+    expectDev(console.error.calls.count()).toBe(1);
+    expectDev(console.error.calls.argsFor(0)[0]).toContain(
+      'render(...): ' +
+        'It looks like the React-rendered content of this container was ' +
+        'removed without using React. This is not supported and will ' +
+        'cause errors. Instead, call ReactDOM.unmountComponentAtNode ' +
+        'to empty a container.',
+    );
+  });
 
-    it('should warn when doing an update to a container manually cleared outside of React', () => {
-      spyOn(console, 'error');
-      // when not messing with the DOM outside of React
-      ReactDOM.render(<div>foo</div>, container);
-      ReactDOM.render(<div>bar</div>, container);
-      expect(container.innerHTML).toBe('<div>bar</div>');
-      // then we mess with the DOM before an update
-      container.innerHTML = '';
-      ReactDOM.render(<div>baz</div>, container);
-      // silently fails to update
-      expectDev(console.error.calls.count()).toBe(1);
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'render(...): ' +
-          'It looks like the React-rendered content of this container was ' +
-          'removed without using React. This is not supported and will ' +
-          'cause errors. Instead, call ReactDOM.unmountComponentAtNode ' +
-          'to empty a container.',
-      );
-    });
-  }
+  it('should warn when doing an update to a container manually updated outside of React', () => {
+    spyOn(console, 'error');
+    // when not messing with the DOM outside of React
+    ReactDOM.render(<div>foo</div>, container);
+    ReactDOM.render(<div>bar</div>, container);
+    expect(container.innerHTML).toBe('<div>bar</div>');
+    // then we mess with the DOM before an update
+    container.innerHTML = '<div>MEOW.</div>';
+    ReactDOM.render(<div>baz</div>, container);
+    // silently fails to update
+    expectDev(console.error.calls.count()).toBe(1);
+    expectDev(console.error.calls.argsFor(0)[0]).toContain(
+      'render(...): ' +
+        'It looks like the React-rendered content of this container was ' +
+        'removed without using React. This is not supported and will ' +
+        'cause errors. Instead, call ReactDOM.unmountComponentAtNode ' +
+        'to empty a container.',
+    );
+  });
+
+  it('should warn when doing an update to a container manually cleared outside of React', () => {
+    spyOn(console, 'error');
+    // when not messing with the DOM outside of React
+    ReactDOM.render(<div>foo</div>, container);
+    ReactDOM.render(<div>bar</div>, container);
+    expect(container.innerHTML).toBe('<div>bar</div>');
+    // then we mess with the DOM before an update
+    container.innerHTML = '';
+    ReactDOM.render(<div>baz</div>, container);
+    // silently fails to update
+    expectDev(console.error.calls.count()).toBe(1);
+    expectDev(console.error.calls.argsFor(0)[0]).toContain(
+      'render(...): ' +
+        'It looks like the React-rendered content of this container was ' +
+        'removed without using React. This is not supported and will ' +
+        'cause errors. Instead, call ReactDOM.unmountComponentAtNode ' +
+        'to empty a container.',
+    );
+  });
 });
 
 // disableNewFiberFeatures currently defaults to true in test
diff --git a/src/renderers/dom/fiber/__tests__/ReactDOMFiberAsync-test.js b/src/renderers/dom/fiber/__tests__/ReactDOMFiberAsync-test.js
index 8b1211c43ff..02b05e239c2 100644
--- a/src/renderers/dom/fiber/__tests__/ReactDOMFiberAsync-test.js
+++ b/src/renderers/dom/fiber/__tests__/ReactDOMFiberAsync-test.js
@@ -1,5 +1,4 @@
 var React = require('react');
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 var ReactFeatureFlags = require('ReactFeatureFlags');
 
 var ReactDOM;
@@ -25,260 +24,252 @@ describe('ReactDOMFiberAsync', () => {
     expect(ops).toEqual(['Hi', 'Bye']);
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    it('renders synchronously when feature flag is disabled', () => {
+  it('renders synchronously when feature flag is disabled', () => {
+    ReactDOM.render(<AsyncComponent><div>Hi</div></AsyncComponent>, container);
+    expect(container.textContent).toEqual('Hi');
+
+    ReactDOM.render(<AsyncComponent><div>Bye</div></AsyncComponent>, container);
+    expect(container.textContent).toEqual('Bye');
+  });
+
+  describe('with feature flag enabled', () => {
+    beforeEach(() => {
+      jest.resetModules();
+      ReactFeatureFlags = require('ReactFeatureFlags');
+      container = document.createElement('div');
+      ReactFeatureFlags.enableAsyncSubtreeAPI = true;
+      ReactDOM = require('react-dom');
+    });
+
+    it('AsyncComponent at the root makes the entire tree async', () => {
       ReactDOM.render(
         <AsyncComponent><div>Hi</div></AsyncComponent>,
         container,
       );
+      expect(container.textContent).toEqual('');
+      jest.runAllTimers();
       expect(container.textContent).toEqual('Hi');
 
       ReactDOM.render(
         <AsyncComponent><div>Bye</div></AsyncComponent>,
         container,
       );
+      expect(container.textContent).toEqual('Hi');
+      jest.runAllTimers();
       expect(container.textContent).toEqual('Bye');
     });
 
-    describe('with feature flag enabled', () => {
-      beforeEach(() => {
-        jest.resetModules();
-        ReactFeatureFlags = require('ReactFeatureFlags');
-        container = document.createElement('div');
-        ReactFeatureFlags.enableAsyncSubtreeAPI = true;
-        ReactDOM = require('react-dom');
-      });
-
-      it('AsyncComponent at the root makes the entire tree async', () => {
-        ReactDOM.render(
-          <AsyncComponent><div>Hi</div></AsyncComponent>,
-          container,
-        );
-        expect(container.textContent).toEqual('');
-        jest.runAllTimers();
-        expect(container.textContent).toEqual('Hi');
-
-        ReactDOM.render(
-          <AsyncComponent><div>Bye</div></AsyncComponent>,
-          container,
-        );
-        expect(container.textContent).toEqual('Hi');
-        jest.runAllTimers();
-        expect(container.textContent).toEqual('Bye');
-      });
-
-      it('updates inside an async tree are async by default', () => {
-        let instance;
-        class Component extends React.Component {
-          state = {step: 0};
-          render() {
-            instance = this;
-            return <div>{this.state.step}</div>;
-          }
+    it('updates inside an async tree are async by default', () => {
+      let instance;
+      class Component extends React.Component {
+        state = {step: 0};
+        render() {
+          instance = this;
+          return <div>{this.state.step}</div>;
         }
+      }
 
-        ReactDOM.render(
-          <AsyncComponent><Component /></AsyncComponent>,
-          container,
-        );
-        expect(container.textContent).toEqual('');
-        jest.runAllTimers();
-        expect(container.textContent).toEqual('0');
-
-        instance.setState({step: 1});
-        expect(container.textContent).toEqual('0');
-        jest.runAllTimers();
-        expect(container.textContent).toEqual('1');
-      });
+      ReactDOM.render(
+        <AsyncComponent><Component /></AsyncComponent>,
+        container,
+      );
+      expect(container.textContent).toEqual('');
+      jest.runAllTimers();
+      expect(container.textContent).toEqual('0');
+
+      instance.setState({step: 1});
+      expect(container.textContent).toEqual('0');
+      jest.runAllTimers();
+      expect(container.textContent).toEqual('1');
+    });
 
-      it('AsyncComponent creates an async subtree', () => {
-        let instance;
-        class Component extends React.unstable_AsyncComponent {
-          state = {step: 0};
-          render() {
-            instance = this;
-            return <div>{this.state.step}</div>;
-          }
+    it('AsyncComponent creates an async subtree', () => {
+      let instance;
+      class Component extends React.unstable_AsyncComponent {
+        state = {step: 0};
+        render() {
+          instance = this;
+          return <div>{this.state.step}</div>;
         }
+      }
 
-        ReactDOM.render(<div><Component /></div>, container);
-        jest.runAllTimers();
+      ReactDOM.render(<div><Component /></div>, container);
+      jest.runAllTimers();
 
-        instance.setState({step: 1});
-        expect(container.textContent).toEqual('0');
-        jest.runAllTimers();
-        expect(container.textContent).toEqual('1');
-      });
+      instance.setState({step: 1});
+      expect(container.textContent).toEqual('0');
+      jest.runAllTimers();
+      expect(container.textContent).toEqual('1');
+    });
 
-      it('updates inside an async subtree are async by default', () => {
-        class Component extends React.unstable_AsyncComponent {
-          render() {
-            return <Child />;
-          }
+    it('updates inside an async subtree are async by default', () => {
+      class Component extends React.unstable_AsyncComponent {
+        render() {
+          return <Child />;
         }
-
-        let instance;
-        class Child extends React.Component {
-          state = {step: 0};
-          render() {
-            instance = this;
-            return <div>{this.state.step}</div>;
-          }
+      }
+
+      let instance;
+      class Child extends React.Component {
+        state = {step: 0};
+        render() {
+          instance = this;
+          return <div>{this.state.step}</div>;
         }
+      }
 
-        ReactDOM.render(<div><Component /></div>, container);
-        jest.runAllTimers();
+      ReactDOM.render(<div><Component /></div>, container);
+      jest.runAllTimers();
 
-        instance.setState({step: 1});
-        expect(container.textContent).toEqual('0');
-        jest.runAllTimers();
-        expect(container.textContent).toEqual('1');
-      });
+      instance.setState({step: 1});
+      expect(container.textContent).toEqual('0');
+      jest.runAllTimers();
+      expect(container.textContent).toEqual('1');
+    });
 
-      it('flushSync batches sync updates and flushes them at the end of the batch', () => {
-        let ops = [];
-        let instance;
-
-        class Component extends React.Component {
-          state = {text: ''};
-          push(val) {
-            this.setState(state => ({text: state.text + val}));
-          }
-          componentDidUpdate() {
-            ops.push(this.state.text);
-          }
-          render() {
-            instance = this;
-            return <span>{this.state.text}</span>;
-          }
+    it('flushSync batches sync updates and flushes them at the end of the batch', () => {
+      let ops = [];
+      let instance;
+
+      class Component extends React.Component {
+        state = {text: ''};
+        push(val) {
+          this.setState(state => ({text: state.text + val}));
+        }
+        componentDidUpdate() {
+          ops.push(this.state.text);
         }
+        render() {
+          instance = this;
+          return <span>{this.state.text}</span>;
+        }
+      }
 
-        ReactDOM.render(<Component />, container);
+      ReactDOM.render(<Component />, container);
 
-        instance.push('A');
-        expect(ops).toEqual(['A']);
-        expect(container.textContent).toEqual('A');
+      instance.push('A');
+      expect(ops).toEqual(['A']);
+      expect(container.textContent).toEqual('A');
 
-        ReactDOM.flushSync(() => {
-          instance.push('B');
-          instance.push('C');
-          // Not flushed yet
-          expect(container.textContent).toEqual('A');
-          expect(ops).toEqual(['A']);
-        });
-        expect(container.textContent).toEqual('ABC');
-        expect(ops).toEqual(['A', 'ABC']);
-        instance.push('D');
-        expect(container.textContent).toEqual('ABCD');
-        expect(ops).toEqual(['A', 'ABC', 'ABCD']);
+      ReactDOM.flushSync(() => {
+        instance.push('B');
+        instance.push('C');
+        // Not flushed yet
+        expect(container.textContent).toEqual('A');
+        expect(ops).toEqual(['A']);
       });
+      expect(container.textContent).toEqual('ABC');
+      expect(ops).toEqual(['A', 'ABC']);
+      instance.push('D');
+      expect(container.textContent).toEqual('ABCD');
+      expect(ops).toEqual(['A', 'ABC', 'ABCD']);
+    });
+
+    it('flushSync flushes updates even if nested inside another flushSync', () => {
+      let ops = [];
+      let instance;
 
-      it('flushSync flushes updates even if nested inside another flushSync', () => {
-        let ops = [];
-        let instance;
-
-        class Component extends React.Component {
-          state = {text: ''};
-          push(val) {
-            this.setState(state => ({text: state.text + val}));
-          }
-          componentDidUpdate() {
-            ops.push(this.state.text);
-          }
-          render() {
-            instance = this;
-            return <span>{this.state.text}</span>;
-          }
+      class Component extends React.Component {
+        state = {text: ''};
+        push(val) {
+          this.setState(state => ({text: state.text + val}));
         }
+        componentDidUpdate() {
+          ops.push(this.state.text);
+        }
+        render() {
+          instance = this;
+          return <span>{this.state.text}</span>;
+        }
+      }
 
-        ReactDOM.render(<Component />, container);
+      ReactDOM.render(<Component />, container);
 
-        instance.push('A');
-        expect(ops).toEqual(['A']);
+      instance.push('A');
+      expect(ops).toEqual(['A']);
+      expect(container.textContent).toEqual('A');
+
+      ReactDOM.flushSync(() => {
+        instance.push('B');
+        instance.push('C');
+        // Not flushed yet
         expect(container.textContent).toEqual('A');
+        expect(ops).toEqual(['A']);
 
         ReactDOM.flushSync(() => {
-          instance.push('B');
-          instance.push('C');
-          // Not flushed yet
-          expect(container.textContent).toEqual('A');
-          expect(ops).toEqual(['A']);
-
-          ReactDOM.flushSync(() => {
-            instance.push('D');
-          });
-          // The nested flushSync caused everything to flush.
-          expect(container.textContent).toEqual('ABCD');
-          expect(ops).toEqual(['A', 'ABCD']);
+          instance.push('D');
         });
+        // The nested flushSync caused everything to flush.
         expect(container.textContent).toEqual('ABCD');
         expect(ops).toEqual(['A', 'ABCD']);
       });
+      expect(container.textContent).toEqual('ABCD');
+      expect(ops).toEqual(['A', 'ABCD']);
+    });
 
-      it('flushSync throws if already performing work', () => {
-        class Component extends React.Component {
-          componentDidUpdate() {
-            ReactDOM.flushSync(() => {});
-          }
-          render() {
-            return null;
-          }
+    it('flushSync throws if already performing work', () => {
+      class Component extends React.Component {
+        componentDidUpdate() {
+          ReactDOM.flushSync(() => {});
+        }
+        render() {
+          return null;
         }
+      }
 
-        // Initial mount
-        ReactDOM.render(<Component />, container);
-        // Update
-        expect(() => ReactDOM.render(<Component />, container)).toThrow(
-          'flushSync was called from inside a lifecycle method',
-        );
-      });
+      // Initial mount
+      ReactDOM.render(<Component />, container);
+      // Update
+      expect(() => ReactDOM.render(<Component />, container)).toThrow(
+        'flushSync was called from inside a lifecycle method',
+      );
+    });
+
+    it('flushSync flushes updates before end of the tick', () => {
+      let ops = [];
+      let instance;
 
-      it('flushSync flushes updates before end of the tick', () => {
-        let ops = [];
-        let instance;
-
-        class Component extends React.unstable_AsyncComponent {
-          state = {text: ''};
-          push(val) {
-            this.setState(state => ({text: state.text + val}));
-          }
-          componentDidUpdate() {
-            ops.push(this.state.text);
-          }
-          render() {
-            instance = this;
-            return <span>{this.state.text}</span>;
-          }
+      class Component extends React.unstable_AsyncComponent {
+        state = {text: ''};
+        push(val) {
+          this.setState(state => ({text: state.text + val}));
         }
+        componentDidUpdate() {
+          ops.push(this.state.text);
+        }
+        render() {
+          instance = this;
+          return <span>{this.state.text}</span>;
+        }
+      }
 
-        ReactDOM.render(<Component />, container);
-        jest.runAllTimers();
+      ReactDOM.render(<Component />, container);
+      jest.runAllTimers();
 
-        // Updates are async by default
-        instance.push('A');
-        expect(ops).toEqual([]);
-        expect(container.textContent).toEqual('');
+      // Updates are async by default
+      instance.push('A');
+      expect(ops).toEqual([]);
+      expect(container.textContent).toEqual('');
 
-        ReactDOM.flushSync(() => {
-          instance.push('B');
-          instance.push('C');
-          // Not flushed yet
-          expect(container.textContent).toEqual('');
-          expect(ops).toEqual([]);
-        });
-        // Only the active updates have flushed
-        expect(container.textContent).toEqual('BC');
-        expect(ops).toEqual(['BC']);
-
-        instance.push('D');
-        expect(container.textContent).toEqual('BC');
-        expect(ops).toEqual(['BC']);
-
-        // Flush the async updates
-        jest.runAllTimers();
-        expect(container.textContent).toEqual('BCAD');
-        expect(ops).toEqual(['BC', 'BCAD']);
+      ReactDOM.flushSync(() => {
+        instance.push('B');
+        instance.push('C');
+        // Not flushed yet
+        expect(container.textContent).toEqual('');
+        expect(ops).toEqual([]);
       });
+      // Only the active updates have flushed
+      expect(container.textContent).toEqual('BC');
+      expect(ops).toEqual(['BC']);
+
+      instance.push('D');
+      expect(container.textContent).toEqual('BC');
+      expect(ops).toEqual(['BC']);
+
+      // Flush the async updates
+      jest.runAllTimers();
+      expect(container.textContent).toEqual('BCAD');
+      expect(ops).toEqual(['BC', 'BCAD']);
     });
-  }
+  });
 });
diff --git a/src/renderers/dom/fiber/wrappers/ReactDOMFiberInput.js b/src/renderers/dom/fiber/wrappers/ReactDOMFiberInput.js
index 88d4abb464d..cc4035d1bc8 100644
--- a/src/renderers/dom/fiber/wrappers/ReactDOMFiberInput.js
+++ b/src/renderers/dom/fiber/wrappers/ReactDOMFiberInput.js
@@ -20,17 +20,15 @@ type InputWithWrapperState = HTMLInputElement & {
   },
 };
 
-var DOMPropertyOperations = require('DOMPropertyOperations');
-var ReactControlledValuePropTypes = require('ReactControlledValuePropTypes');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var {getCurrentFiberOwnerName} = require('ReactDebugCurrentFiber');
-
-if (__DEV__) {
-  var {getCurrentFiberStackAddendum} = require('ReactDebugCurrentFiber');
-  var warning = require('fbjs/lib/warning');
-}
-
-var invariant = require('fbjs/lib/invariant');
+import {setValueForProperty} from 'DOMPropertyOperations';
+import {checkPropTypes} from 'ReactControlledValuePropTypes';
+import {getFiberCurrentPropsFromNode} from 'ReactDOMComponentTree';
+import {
+  getCurrentFiberOwnerName,
+  getCurrentFiberStackAddendum,
+} from 'ReactDebugCurrentFiber';
+import warning from 'fbjs/lib/warning';
+import invariant from 'fbjs/lib/invariant';
 
 var didWarnValueDefaultValue = false;
 var didWarnCheckedDefaultChecked = false;
@@ -58,238 +56,229 @@ function isControlled(props) {
  *
  * See http://www.w3.org/TR/2012/WD-html5-20121025/the-input-element.html
  */
-var ReactDOMInput = {
-  getHostProps: function(element: Element, props: Object) {
-    var node = ((element: any): InputWithWrapperState);
-    var value = props.value;
-    var checked = props.checked;
 
-    var hostProps = Object.assign(
-      {
-        // Make sure we set .type before any other properties (setting .value
-        // before .type means .value is lost in IE11 and below)
-        type: undefined,
-        // Make sure we set .step before .value (setting .value before .step
-        // means .value is rounded on mount, based upon step precision)
-        step: undefined,
-        // Make sure we set .min & .max before .value (to ensure proper order
-        // in corner cases such as min or max deriving from value, e.g. Issue #7170)
-        min: undefined,
-        max: undefined,
-      },
-      props,
-      {
-        defaultChecked: undefined,
-        defaultValue: undefined,
-        value: value != null ? value : node._wrapperState.initialValue,
-        checked: checked != null ? checked : node._wrapperState.initialChecked,
-      },
-    );
+export function getHostProps(element: Element, props: Object) {
+  var node = ((element: any): InputWithWrapperState);
+  var value = props.value;
+  var checked = props.checked;
 
-    return hostProps;
-  },
+  var hostProps = Object.assign(
+    {
+      // Make sure we set .type before any other properties (setting .value
+      // before .type means .value is lost in IE11 and below)
+      type: undefined,
+      // Make sure we set .step before .value (setting .value before .step
+      // means .value is rounded on mount, based upon step precision)
+      step: undefined,
+      // Make sure we set .min & .max before .value (to ensure proper order
+      // in corner cases such as min or max deriving from value, e.g. Issue #7170)
+      min: undefined,
+      max: undefined,
+    },
+    props,
+    {
+      defaultChecked: undefined,
+      defaultValue: undefined,
+      value: value != null ? value : node._wrapperState.initialValue,
+      checked: checked != null ? checked : node._wrapperState.initialChecked,
+    },
+  );
 
-  initWrapperState: function(element: Element, props: Object) {
-    if (__DEV__) {
-      ReactControlledValuePropTypes.checkPropTypes(
-        'input',
-        props,
-        getCurrentFiberStackAddendum,
-      );
+  return hostProps;
+}
 
-      if (
-        props.checked !== undefined &&
-        props.defaultChecked !== undefined &&
-        !didWarnCheckedDefaultChecked
-      ) {
-        warning(
-          false,
-          '%s contains an input of type %s with both checked and defaultChecked props. ' +
-            'Input elements must be either controlled or uncontrolled ' +
-            '(specify either the checked prop, or the defaultChecked prop, but not ' +
-            'both). Decide between using a controlled or uncontrolled input ' +
-            'element and remove one of these props. More info: ' +
-            'https://fb.me/react-controlled-components',
-          getCurrentFiberOwnerName() || 'A component',
-          props.type,
-        );
-        didWarnCheckedDefaultChecked = true;
-      }
-      if (
-        props.value !== undefined &&
-        props.defaultValue !== undefined &&
-        !didWarnValueDefaultValue
-      ) {
-        warning(
-          false,
-          '%s contains an input of type %s with both value and defaultValue props. ' +
-            'Input elements must be either controlled or uncontrolled ' +
-            '(specify either the value prop, or the defaultValue prop, but not ' +
-            'both). Decide between using a controlled or uncontrolled input ' +
-            'element and remove one of these props. More info: ' +
-            'https://fb.me/react-controlled-components',
-          getCurrentFiberOwnerName() || 'A component',
-          props.type,
-        );
-        didWarnValueDefaultValue = true;
-      }
+export function initWrapperState(element: Element, props: Object) {
+  if (__DEV__) {
+    checkPropTypes('input', props, getCurrentFiberStackAddendum);
+
+    if (
+      props.checked !== undefined &&
+      props.defaultChecked !== undefined &&
+      !didWarnCheckedDefaultChecked
+    ) {
+      warning(
+        false,
+        '%s contains an input of type %s with both checked and defaultChecked props. ' +
+          'Input elements must be either controlled or uncontrolled ' +
+          '(specify either the checked prop, or the defaultChecked prop, but not ' +
+          'both). Decide between using a controlled or uncontrolled input ' +
+          'element and remove one of these props. More info: ' +
+          'https://fb.me/react-controlled-components',
+        getCurrentFiberOwnerName() || 'A component',
+        props.type,
+      );
+      didWarnCheckedDefaultChecked = true;
+    }
+    if (
+      props.value !== undefined &&
+      props.defaultValue !== undefined &&
+      !didWarnValueDefaultValue
+    ) {
+      warning(
+        false,
+        '%s contains an input of type %s with both value and defaultValue props. ' +
+          'Input elements must be either controlled or uncontrolled ' +
+          '(specify either the value prop, or the defaultValue prop, but not ' +
+          'both). Decide between using a controlled or uncontrolled input ' +
+          'element and remove one of these props. More info: ' +
+          'https://fb.me/react-controlled-components',
+        getCurrentFiberOwnerName() || 'A component',
+        props.type,
+      );
+      didWarnValueDefaultValue = true;
     }
+  }
 
-    var defaultValue = props.defaultValue;
-    var node = ((element: any): InputWithWrapperState);
-    node._wrapperState = {
-      initialChecked: props.checked != null
-        ? props.checked
-        : props.defaultChecked,
-      initialValue: props.value != null ? props.value : defaultValue,
-      controlled: isControlled(props),
-    };
-  },
+  var defaultValue = props.defaultValue;
+  var node = ((element: any): InputWithWrapperState);
+  node._wrapperState = {
+    initialChecked: props.checked != null
+      ? props.checked
+      : props.defaultChecked,
+    initialValue: props.value != null ? props.value : defaultValue,
+    controlled: isControlled(props),
+  };
+}
 
-  updateWrapper: function(element: Element, props: Object) {
-    var node = ((element: any): InputWithWrapperState);
-    if (__DEV__) {
-      var controlled = isControlled(props);
+export function updateWrapper(element: Element, props: Object) {
+  var node = ((element: any): InputWithWrapperState);
+  if (__DEV__) {
+    var controlled = isControlled(props);
 
-      if (
-        !node._wrapperState.controlled &&
-        controlled &&
-        !didWarnUncontrolledToControlled
-      ) {
-        warning(
-          false,
-          'A component is changing an uncontrolled input of type %s to be controlled. ' +
-            'Input elements should not switch from uncontrolled to controlled (or vice versa). ' +
-            'Decide between using a controlled or uncontrolled input ' +
-            'element for the lifetime of the component. More info: https://fb.me/react-controlled-components%s',
-          props.type,
-          getCurrentFiberStackAddendum(),
-        );
-        didWarnUncontrolledToControlled = true;
-      }
-      if (
-        node._wrapperState.controlled &&
-        !controlled &&
-        !didWarnControlledToUncontrolled
-      ) {
-        warning(
-          false,
-          'A component is changing a controlled input of type %s to be uncontrolled. ' +
-            'Input elements should not switch from controlled to uncontrolled (or vice versa). ' +
-            'Decide between using a controlled or uncontrolled input ' +
-            'element for the lifetime of the component. More info: https://fb.me/react-controlled-components%s',
-          props.type,
-          getCurrentFiberStackAddendum(),
-        );
-        didWarnControlledToUncontrolled = true;
-      }
+    if (
+      !node._wrapperState.controlled &&
+      controlled &&
+      !didWarnUncontrolledToControlled
+    ) {
+      warning(
+        false,
+        'A component is changing an uncontrolled input of type %s to be controlled. ' +
+          'Input elements should not switch from uncontrolled to controlled (or vice versa). ' +
+          'Decide between using a controlled or uncontrolled input ' +
+          'element for the lifetime of the component. More info: https://fb.me/react-controlled-components%s',
+        props.type,
+        getCurrentFiberStackAddendum(),
+      );
+      didWarnUncontrolledToControlled = true;
     }
-
-    var checked = props.checked;
-    if (checked != null) {
-      DOMPropertyOperations.setValueForProperty(
-        node,
-        'checked',
-        checked || false,
+    if (
+      node._wrapperState.controlled &&
+      !controlled &&
+      !didWarnControlledToUncontrolled
+    ) {
+      warning(
+        false,
+        'A component is changing a controlled input of type %s to be uncontrolled. ' +
+          'Input elements should not switch from controlled to uncontrolled (or vice versa). ' +
+          'Decide between using a controlled or uncontrolled input ' +
+          'element for the lifetime of the component. More info: https://fb.me/react-controlled-components%s',
+        props.type,
+        getCurrentFiberStackAddendum(),
       );
+      didWarnControlledToUncontrolled = true;
     }
+  }
 
-    var value = props.value;
-    if (value != null) {
-      if (value === 0 && node.value === '') {
-        node.value = '0';
-        // Note: IE9 reports a number inputs as 'text', so check props instead.
-      } else if (props.type === 'number') {
-        // Simulate `input.valueAsNumber`. IE9 does not support it
-        var valueAsNumber = parseFloat(node.value) || 0;
+  var checked = props.checked;
+  if (checked != null) {
+    setValueForProperty(node, 'checked', checked || false);
+  }
 
-        if (
-          // eslint-disable-next-line
-          value != valueAsNumber ||
-          // eslint-disable-next-line
-          (value == valueAsNumber && node.value != value)
-        ) {
-          // Cast `value` to a string to ensure the value is set correctly. While
-          // browsers typically do this as necessary, jsdom doesn't.
-          node.value = '' + value;
-        }
-      } else if (node.value !== '' + value) {
+  var value = props.value;
+  if (value != null) {
+    if (value === 0 && node.value === '') {
+      node.value = '0';
+      // Note: IE9 reports a number inputs as 'text', so check props instead.
+    } else if (props.type === 'number') {
+      // Simulate `input.valueAsNumber`. IE9 does not support it
+      var valueAsNumber = parseFloat(node.value) || 0;
+
+      if (
+        // eslint-disable-next-line
+        value != valueAsNumber ||
+        // eslint-disable-next-line
+        (value == valueAsNumber && node.value != value)
+      ) {
         // Cast `value` to a string to ensure the value is set correctly. While
         // browsers typically do this as necessary, jsdom doesn't.
         node.value = '' + value;
       }
-    } else {
-      if (props.value == null && props.defaultValue != null) {
-        // In Chrome, assigning defaultValue to certain input types triggers input validation.
-        // For number inputs, the display value loses trailing decimal points. For email inputs,
-        // Chrome raises "The specified value <x> is not a valid email address".
-        //
-        // Here we check to see if the defaultValue has actually changed, avoiding these problems
-        // when the user is inputting text
-        //
-        // https://github.com/facebook/react/issues/7253
-        if (node.defaultValue !== '' + props.defaultValue) {
-          node.defaultValue = '' + props.defaultValue;
-        }
-      }
-      if (props.checked == null && props.defaultChecked != null) {
-        node.defaultChecked = !!props.defaultChecked;
+    } else if (node.value !== '' + value) {
+      // Cast `value` to a string to ensure the value is set correctly. While
+      // browsers typically do this as necessary, jsdom doesn't.
+      node.value = '' + value;
+    }
+  } else {
+    if (props.value == null && props.defaultValue != null) {
+      // In Chrome, assigning defaultValue to certain input types triggers input validation.
+      // For number inputs, the display value loses trailing decimal points. For email inputs,
+      // Chrome raises "The specified value <x> is not a valid email address".
+      //
+      // Here we check to see if the defaultValue has actually changed, avoiding these problems
+      // when the user is inputting text
+      //
+      // https://github.com/facebook/react/issues/7253
+      if (node.defaultValue !== '' + props.defaultValue) {
+        node.defaultValue = '' + props.defaultValue;
       }
     }
-  },
+    if (props.checked == null && props.defaultChecked != null) {
+      node.defaultChecked = !!props.defaultChecked;
+    }
+  }
+}
 
-  postMountWrapper: function(element: Element, props: Object) {
-    var node = ((element: any): InputWithWrapperState);
+export function postMountWrapper(element: Element, props: Object) {
+  var node = ((element: any): InputWithWrapperState);
 
-    // Detach value from defaultValue. We won't do anything if we're working on
-    // submit or reset inputs as those values & defaultValues are linked. They
-    // are not resetable nodes so this operation doesn't matter and actually
-    // removes browser-default values (eg "Submit Query") when no value is
-    // provided.
+  // Detach value from defaultValue. We won't do anything if we're working on
+  // submit or reset inputs as those values & defaultValues are linked. They
+  // are not resetable nodes so this operation doesn't matter and actually
+  // removes browser-default values (eg "Submit Query") when no value is
+  // provided.
 
-    switch (props.type) {
-      case 'submit':
-      case 'reset':
-        break;
-      case 'color':
-      case 'date':
-      case 'datetime':
-      case 'datetime-local':
-      case 'month':
-      case 'time':
-      case 'week':
-        // This fixes the no-show issue on iOS Safari and Android Chrome:
-        // https://github.com/facebook/react/issues/7233
-        node.value = '';
-        node.value = node.defaultValue;
-        break;
-      default:
-        node.value = node.value;
-        break;
-    }
+  switch (props.type) {
+    case 'submit':
+    case 'reset':
+      break;
+    case 'color':
+    case 'date':
+    case 'datetime':
+    case 'datetime-local':
+    case 'month':
+    case 'time':
+    case 'week':
+      // This fixes the no-show issue on iOS Safari and Android Chrome:
+      // https://github.com/facebook/react/issues/7233
+      node.value = '';
+      node.value = node.defaultValue;
+      break;
+    default:
+      node.value = node.value;
+      break;
+  }
 
-    // Normally, we'd just do `node.checked = node.checked` upon initial mount, less this bug
-    // this is needed to work around a chrome bug where setting defaultChecked
-    // will sometimes influence the value of checked (even after detachment).
-    // Reference: https://bugs.chromium.org/p/chromium/issues/detail?id=608416
-    // We need to temporarily unset name to avoid disrupting radio button groups.
-    var name = node.name;
-    if (name !== '') {
-      node.name = '';
-    }
-    node.defaultChecked = !node.defaultChecked;
-    node.defaultChecked = !node.defaultChecked;
-    if (name !== '') {
-      node.name = name;
-    }
-  },
+  // Normally, we'd just do `node.checked = node.checked` upon initial mount, less this bug
+  // this is needed to work around a chrome bug where setting defaultChecked
+  // will sometimes influence the value of checked (even after detachment).
+  // Reference: https://bugs.chromium.org/p/chromium/issues/detail?id=608416
+  // We need to temporarily unset name to avoid disrupting radio button groups.
+  var name = node.name;
+  if (name !== '') {
+    node.name = '';
+  }
+  node.defaultChecked = !node.defaultChecked;
+  node.defaultChecked = !node.defaultChecked;
+  if (name !== '') {
+    node.name = name;
+  }
+}
 
-  restoreControlledState: function(element: Element, props: Object) {
-    var node = ((element: any): InputWithWrapperState);
-    ReactDOMInput.updateWrapper(node, props);
-    updateNamedCousins(node, props);
-  },
-};
+export function restoreControlledState(element: Element, props: Object) {
+  var node = ((element: any): InputWithWrapperState);
+  updateWrapper(node, props);
+  updateNamedCousins(node, props);
+}
 
 function updateNamedCousins(rootNode, props) {
   var name = props.name;
@@ -320,9 +309,7 @@ function updateNamedCousins(rootNode, props) {
       // and the same name are rendered into the same form (same as #1939).
       // That's probably okay; we don't support it just as we don't support
       // mixing React radio buttons with non-React ones.
-      var otherProps = ReactDOMComponentTree.getFiberCurrentPropsFromNode(
-        otherNode,
-      );
+      var otherProps = getFiberCurrentPropsFromNode(otherNode);
       invariant(
         otherProps,
         'ReactDOMInput: Mixing React and non-React radio inputs with the ' +
@@ -331,9 +318,7 @@ function updateNamedCousins(rootNode, props) {
       // If this is a controlled radio button group, forcing the input that
       // was previously checked to update will cause it to be come re-checked
       // as appropriate.
-      ReactDOMInput.updateWrapper(otherNode, otherProps);
+      updateWrapper(otherNode, otherProps);
     }
   }
 }
-
-module.exports = ReactDOMInput;
diff --git a/src/renderers/dom/fiber/wrappers/ReactDOMFiberOption.js b/src/renderers/dom/fiber/wrappers/ReactDOMFiberOption.js
index 5dff76a60ae..32aa45f806b 100644
--- a/src/renderers/dom/fiber/wrappers/ReactDOMFiberOption.js
+++ b/src/renderers/dom/fiber/wrappers/ReactDOMFiberOption.js
@@ -12,11 +12,10 @@
 
 'use strict';
 
-var React = require('react');
+import React from 'react';
+import warning from 'fbjs/lib/warning';
 
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+const {Children} = React;
 
 function flattenChildren(children) {
   var content = '';
@@ -25,7 +24,7 @@ function flattenChildren(children) {
   // invalid types are ignored.
   // We can silently skip them because invalid DOM nesting warning
   // catches these cases in Fiber.
-  React.Children.forEach(children, function(child) {
+  Children.forEach(children, function(child) {
     if (child == null) {
       return;
     }
@@ -40,36 +39,33 @@ function flattenChildren(children) {
 /**
  * Implements an <option> host component that warns when `selected` is set.
  */
-var ReactDOMOption = {
-  validateProps: function(element: Element, props: Object) {
-    // TODO (yungsters): Remove support for `selected` in <option>.
-    if (__DEV__) {
-      warning(
-        props.selected == null,
-        'Use the `defaultValue` or `value` props on <select> instead of ' +
-          'setting `selected` on <option>.',
-      );
-    }
-  },
 
-  postMountWrapper: function(element: Element, props: Object) {
-    // value="" should make a value attribute (#6219)
-    if (props.value != null) {
-      element.setAttribute('value', props.value);
-    }
-  },
+export function validateProps(element: Element, props: Object) {
+  // TODO (yungsters): Remove support for `selected` in <option>.
+  if (__DEV__) {
+    warning(
+      props.selected == null,
+      'Use the `defaultValue` or `value` props on <select> instead of ' +
+        'setting `selected` on <option>.',
+    );
+  }
+}
 
-  getHostProps: function(element: Element, props: Object) {
-    var hostProps = Object.assign({children: undefined}, props);
+export function postMountWrapper(element: Element, props: Object) {
+  // value="" should make a value attribute (#6219)
+  if (props.value != null) {
+    element.setAttribute('value', props.value);
+  }
+}
 
-    var content = flattenChildren(props.children);
+export function getHostProps(element: Element, props: Object) {
+  var hostProps = Object.assign({children: undefined}, props);
 
-    if (content) {
-      hostProps.children = content;
-    }
+  var content = flattenChildren(props.children);
 
-    return hostProps;
-  },
-};
+  if (content) {
+    hostProps.children = content;
+  }
 
-module.exports = ReactDOMOption;
+  return hostProps;
+}
diff --git a/src/renderers/dom/fiber/wrappers/ReactDOMFiberSelect.js b/src/renderers/dom/fiber/wrappers/ReactDOMFiberSelect.js
index 6a5599b7072..e5e61ea7a80 100644
--- a/src/renderers/dom/fiber/wrappers/ReactDOMFiberSelect.js
+++ b/src/renderers/dom/fiber/wrappers/ReactDOMFiberSelect.js
@@ -19,13 +19,15 @@ type SelectWithWrapperState = HTMLSelectElement & {
   },
 };
 
-var ReactControlledValuePropTypes = require('ReactControlledValuePropTypes');
-var {getCurrentFiberOwnerName} = require('ReactDebugCurrentFiber');
+import {checkPropTypes} from 'ReactControlledValuePropTypes';
+import {
+  getCurrentFiberOwnerName,
+  getCurrentFiberStackAddendum,
+} from 'ReactDebugCurrentFiber';
+import warning from 'fbjs/lib/warning';
 
 if (__DEV__) {
   var didWarnValueDefaultValue = false;
-  var warning = require('fbjs/lib/warning');
-  var {getCurrentFiberStackAddendum} = require('ReactDebugCurrentFiber');
 }
 
 function getDeclarationErrorAddendum() {
@@ -42,11 +44,7 @@ var valuePropNames = ['value', 'defaultValue'];
  * Validation function for `value` and `defaultValue`.
  */
 function checkSelectPropTypes(props) {
-  ReactControlledValuePropTypes.checkPropTypes(
-    'select',
-    props,
-    getCurrentFiberStackAddendum,
-  );
+  checkPropTypes('select', props, getCurrentFiberStackAddendum);
 
   for (var i = 0; i < valuePropNames.length; i++) {
     var propName = valuePropNames[i];
@@ -128,86 +126,83 @@ function updateOptions(
  * If `defaultValue` is provided, any options with the supplied values will be
  * selected.
  */
-var ReactDOMSelect = {
-  getHostProps: function(element: Element, props: Object) {
-    return Object.assign({}, props, {
-      value: undefined,
-    });
-  },
 
-  initWrapperState: function(element: Element, props: Object) {
-    var node = ((element: any): SelectWithWrapperState);
-    if (__DEV__) {
-      checkSelectPropTypes(props);
-    }
+export function getHostProps(element: Element, props: Object) {
+  return Object.assign({}, props, {
+    value: undefined,
+  });
+}
 
-    var value = props.value;
-    node._wrapperState = {
-      initialValue: value != null ? value : props.defaultValue,
-      wasMultiple: !!props.multiple,
-    };
-
-    if (__DEV__) {
-      if (
-        props.value !== undefined &&
-        props.defaultValue !== undefined &&
-        !didWarnValueDefaultValue
-      ) {
-        warning(
-          false,
-          'Select elements must be either controlled or uncontrolled ' +
-            '(specify either the value prop, or the defaultValue prop, but not ' +
-            'both). Decide between using a controlled or uncontrolled select ' +
-            'element and remove one of these props. More info: ' +
-            'https://fb.me/react-controlled-components',
-        );
-        didWarnValueDefaultValue = true;
-      }
-    }
-  },
+export function initWrapperState(element: Element, props: Object) {
+  var node = ((element: any): SelectWithWrapperState);
+  if (__DEV__) {
+    checkSelectPropTypes(props);
+  }
 
-  postMountWrapper: function(element: Element, props: Object) {
-    var node = ((element: any): SelectWithWrapperState);
-    node.multiple = !!props.multiple;
-    var value = props.value;
-    if (value != null) {
-      updateOptions(node, !!props.multiple, value);
-    } else if (props.defaultValue != null) {
-      updateOptions(node, !!props.multiple, props.defaultValue);
-    }
-  },
+  var value = props.value;
+  node._wrapperState = {
+    initialValue: value != null ? value : props.defaultValue,
+    wasMultiple: !!props.multiple,
+  };
 
-  postUpdateWrapper: function(element: Element, props: Object) {
-    var node = ((element: any): SelectWithWrapperState);
-    // After the initial mount, we control selected-ness manually so don't pass
-    // this value down
-    node._wrapperState.initialValue = undefined;
-
-    var wasMultiple = node._wrapperState.wasMultiple;
-    node._wrapperState.wasMultiple = !!props.multiple;
-
-    var value = props.value;
-    if (value != null) {
-      updateOptions(node, !!props.multiple, value);
-    } else if (wasMultiple !== !!props.multiple) {
-      // For simplicity, reapply `defaultValue` if `multiple` is toggled.
-      if (props.defaultValue != null) {
-        updateOptions(node, !!props.multiple, props.defaultValue);
-      } else {
-        // Revert the select back to its default unselected state.
-        updateOptions(node, !!props.multiple, props.multiple ? [] : '');
-      }
+  if (__DEV__) {
+    if (
+      props.value !== undefined &&
+      props.defaultValue !== undefined &&
+      !didWarnValueDefaultValue
+    ) {
+      warning(
+        false,
+        'Select elements must be either controlled or uncontrolled ' +
+          '(specify either the value prop, or the defaultValue prop, but not ' +
+          'both). Decide between using a controlled or uncontrolled select ' +
+          'element and remove one of these props. More info: ' +
+          'https://fb.me/react-controlled-components',
+      );
+      didWarnValueDefaultValue = true;
     }
-  },
+  }
+}
 
-  restoreControlledState: function(element: Element, props: Object) {
-    var node = ((element: any): SelectWithWrapperState);
-    var value = props.value;
+export function postMountWrapper(element: Element, props: Object) {
+  var node = ((element: any): SelectWithWrapperState);
+  node.multiple = !!props.multiple;
+  var value = props.value;
+  if (value != null) {
+    updateOptions(node, !!props.multiple, value);
+  } else if (props.defaultValue != null) {
+    updateOptions(node, !!props.multiple, props.defaultValue);
+  }
+}
 
-    if (value != null) {
-      updateOptions(node, !!props.multiple, value);
+export function postUpdateWrapper(element: Element, props: Object) {
+  var node = ((element: any): SelectWithWrapperState);
+  // After the initial mount, we control selected-ness manually so don't pass
+  // this value down
+  node._wrapperState.initialValue = undefined;
+
+  var wasMultiple = node._wrapperState.wasMultiple;
+  node._wrapperState.wasMultiple = !!props.multiple;
+
+  var value = props.value;
+  if (value != null) {
+    updateOptions(node, !!props.multiple, value);
+  } else if (wasMultiple !== !!props.multiple) {
+    // For simplicity, reapply `defaultValue` if `multiple` is toggled.
+    if (props.defaultValue != null) {
+      updateOptions(node, !!props.multiple, props.defaultValue);
+    } else {
+      // Revert the select back to its default unselected state.
+      updateOptions(node, !!props.multiple, props.multiple ? [] : '');
     }
-  },
-};
+  }
+}
 
-module.exports = ReactDOMSelect;
+export function restoreControlledState(element: Element, props: Object) {
+  var node = ((element: any): SelectWithWrapperState);
+  var value = props.value;
+
+  if (value != null) {
+    updateOptions(node, !!props.multiple, value);
+  }
+}
diff --git a/src/renderers/dom/fiber/wrappers/ReactDOMFiberTextarea.js b/src/renderers/dom/fiber/wrappers/ReactDOMFiberTextarea.js
index 4a5383c4c3d..84f26c44cc7 100644
--- a/src/renderers/dom/fiber/wrappers/ReactDOMFiberTextarea.js
+++ b/src/renderers/dom/fiber/wrappers/ReactDOMFiberTextarea.js
@@ -18,14 +18,10 @@ type TextAreaWithWrapperState = HTMLTextAreaElement & {
   },
 };
 
-var ReactControlledValuePropTypes = require('ReactControlledValuePropTypes');
-
-var invariant = require('fbjs/lib/invariant');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var {getCurrentFiberStackAddendum} = require('ReactDebugCurrentFiber');
-}
+import {checkPropTypes} from 'ReactControlledValuePropTypes';
+import {getCurrentFiberStackAddendum} from 'ReactDebugCurrentFiber';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
 
 var didWarnValDefaultVal = false;
 
@@ -44,134 +40,127 @@ var didWarnValDefaultVal = false;
  * The rendered element will be initialized with an empty value, the prop
  * `defaultValue` if specified, or the children content (deprecated).
  */
-var ReactDOMTextarea = {
-  getHostProps: function(element: Element, props: Object) {
-    var node = ((element: any): TextAreaWithWrapperState);
-    invariant(
-      props.dangerouslySetInnerHTML == null,
-      '`dangerouslySetInnerHTML` does not make sense on <textarea>.',
-    );
-
-    // Always set children to the same thing. In IE9, the selection range will
-    // get reset if `textContent` is mutated.  We could add a check in setTextContent
-    // to only set the value if/when the value differs from the node value (which would
-    // completely solve this IE9 bug), but Sebastian+Ben seemed to like this solution.
-    // The value can be a boolean or object so that's why it's forced to be a string.
-    var hostProps = Object.assign({}, props, {
-      value: undefined,
-      defaultValue: undefined,
-      children: '' + node._wrapperState.initialValue,
-    });
-
-    return hostProps;
-  },
 
-  initWrapperState: function(element: Element, props: Object) {
-    var node = ((element: any): TextAreaWithWrapperState);
-    if (__DEV__) {
-      ReactControlledValuePropTypes.checkPropTypes(
-        'textarea',
-        props,
-        getCurrentFiberStackAddendum,
+export function getHostProps(element: Element, props: Object) {
+  var node = ((element: any): TextAreaWithWrapperState);
+  invariant(
+    props.dangerouslySetInnerHTML == null,
+    '`dangerouslySetInnerHTML` does not make sense on <textarea>.',
+  );
+
+  // Always set children to the same thing. In IE9, the selection range will
+  // get reset if `textContent` is mutated.  We could add a check in setTextContent
+  // to only set the value if/when the value differs from the node value (which would
+  // completely solve this IE9 bug), but Sebastian+Ben seemed to like this solution.
+  // The value can be a boolean or object so that's why it's forced to be a string.
+  var hostProps = Object.assign({}, props, {
+    value: undefined,
+    defaultValue: undefined,
+    children: '' + node._wrapperState.initialValue,
+  });
+
+  return hostProps;
+}
+
+export function initWrapperState(element: Element, props: Object) {
+  var node = ((element: any): TextAreaWithWrapperState);
+  if (__DEV__) {
+    checkPropTypes('textarea', props, getCurrentFiberStackAddendum);
+    if (
+      props.value !== undefined &&
+      props.defaultValue !== undefined &&
+      !didWarnValDefaultVal
+    ) {
+      warning(
+        false,
+        'Textarea elements must be either controlled or uncontrolled ' +
+          '(specify either the value prop, or the defaultValue prop, but not ' +
+          'both). Decide between using a controlled or uncontrolled textarea ' +
+          'and remove one of these props. More info: ' +
+          'https://fb.me/react-controlled-components',
       );
-      if (
-        props.value !== undefined &&
-        props.defaultValue !== undefined &&
-        !didWarnValDefaultVal
-      ) {
+      didWarnValDefaultVal = true;
+    }
+  }
+
+  var value = props.value;
+  var initialValue = value;
+
+  // Only bother fetching default value if we're going to use it
+  if (value == null) {
+    var defaultValue = props.defaultValue;
+    // TODO (yungsters): Remove support for children content in <textarea>.
+    var children = props.children;
+    if (children != null) {
+      if (__DEV__) {
         warning(
           false,
-          'Textarea elements must be either controlled or uncontrolled ' +
-            '(specify either the value prop, or the defaultValue prop, but not ' +
-            'both). Decide between using a controlled or uncontrolled textarea ' +
-            'and remove one of these props. More info: ' +
-            'https://fb.me/react-controlled-components',
+          'Use the `defaultValue` or `value` props instead of setting ' +
+            'children on <textarea>.',
         );
-        didWarnValDefaultVal = true;
       }
-    }
-
-    var value = props.value;
-    var initialValue = value;
-
-    // Only bother fetching default value if we're going to use it
-    if (value == null) {
-      var defaultValue = props.defaultValue;
-      // TODO (yungsters): Remove support for children content in <textarea>.
-      var children = props.children;
-      if (children != null) {
-        if (__DEV__) {
-          warning(
-            false,
-            'Use the `defaultValue` or `value` props instead of setting ' +
-              'children on <textarea>.',
-          );
-        }
+      invariant(
+        defaultValue == null,
+        'If you supply `defaultValue` on a <textarea>, do not pass children.',
+      );
+      if (Array.isArray(children)) {
         invariant(
-          defaultValue == null,
-          'If you supply `defaultValue` on a <textarea>, do not pass children.',
+          children.length <= 1,
+          '<textarea> can only have at most one child.',
         );
-        if (Array.isArray(children)) {
-          invariant(
-            children.length <= 1,
-            '<textarea> can only have at most one child.',
-          );
-          children = children[0];
-        }
-
-        defaultValue = '' + children;
+        children = children[0];
       }
-      if (defaultValue == null) {
-        defaultValue = '';
-      }
-      initialValue = defaultValue;
-    }
-
-    node._wrapperState = {
-      initialValue: '' + initialValue,
-    };
-  },
 
-  updateWrapper: function(element: Element, props: Object) {
-    var node = ((element: any): TextAreaWithWrapperState);
-    var value = props.value;
-    if (value != null) {
-      // Cast `value` to a string to ensure the value is set correctly. While
-      // browsers typically do this as necessary, jsdom doesn't.
-      var newValue = '' + value;
-
-      // To avoid side effects (such as losing text selection), only set value if changed
-      if (newValue !== node.value) {
-        node.value = newValue;
-      }
-      if (props.defaultValue == null) {
-        node.defaultValue = newValue;
-      }
+      defaultValue = '' + children;
     }
-    if (props.defaultValue != null) {
-      node.defaultValue = props.defaultValue;
+    if (defaultValue == null) {
+      defaultValue = '';
     }
-  },
+    initialValue = defaultValue;
+  }
 
-  postMountWrapper: function(element: Element, props: Object) {
-    var node = ((element: any): TextAreaWithWrapperState);
-    // This is in postMount because we need access to the DOM node, which is not
-    // available until after the component has mounted.
-    var textContent = node.textContent;
-
-    // Only set node.value if textContent is equal to the expected
-    // initial value. In IE10/IE11 there is a bug where the placeholder attribute
-    // will populate textContent as well.
-    // https://developer.microsoft.com/microsoft-edge/platform/issues/101525/
-    if (textContent === node._wrapperState.initialValue) {
-      node.value = textContent;
+  node._wrapperState = {
+    initialValue: '' + initialValue,
+  };
+}
+
+export function updateWrapper(element: Element, props: Object) {
+  var node = ((element: any): TextAreaWithWrapperState);
+  var value = props.value;
+  if (value != null) {
+    // Cast `value` to a string to ensure the value is set correctly. While
+    // browsers typically do this as necessary, jsdom doesn't.
+    var newValue = '' + value;
+
+    // To avoid side effects (such as losing text selection), only set value if changed
+    if (newValue !== node.value) {
+      node.value = newValue;
     }
-  },
+    if (props.defaultValue == null) {
+      node.defaultValue = newValue;
+    }
+  }
+  if (props.defaultValue != null) {
+    node.defaultValue = props.defaultValue;
+  }
+}
 
-  restoreControlledState: function(element: Element, props: Object) {
-    // DOM component is still mounted; update
-    ReactDOMTextarea.updateWrapper(element, props);
-  },
-};
+export function postMountWrapper(element: Element, props: Object) {
+  var node = ((element: any): TextAreaWithWrapperState);
+  // This is in postMount because we need access to the DOM node, which is not
+  // available until after the component has mounted.
+  var textContent = node.textContent;
+
+  // Only set node.value if textContent is equal to the expected
+  // initial value. In IE10/IE11 there is a bug where the placeholder attribute
+  // will populate textContent as well.
+  // https://developer.microsoft.com/microsoft-edge/platform/issues/101525/
+  if (textContent === node._wrapperState.initialValue) {
+    node.value = textContent;
+  }
+}
 
-module.exports = ReactDOMTextarea;
+export function restoreControlledState(element: Element, props: Object) {
+  // DOM component is still mounted; update
+  updateWrapper(element, props);
+}
diff --git a/src/renderers/dom/shared/CSSProperty.js b/src/renderers/dom/shared/CSSProperty.js
index 7a33c3ab61a..b84c89899f9 100644
--- a/src/renderers/dom/shared/CSSProperty.js
+++ b/src/renderers/dom/shared/CSSProperty.js
@@ -14,7 +14,7 @@
 /**
  * CSS properties which accept numbers but are not in units of "px".
  */
-var isUnitlessNumber = {
+export const isUnitlessNumber = {
   animationIterationCount: true,
   borderImageOutset: true,
   borderImageSlice: true,
@@ -93,7 +93,7 @@ Object.keys(isUnitlessNumber).forEach(function(prop) {
  * behave without any problems. Curiously, list-style works too without any
  * special prodding.
  */
-var shorthandPropertyExpansions = {
+export const shorthandPropertyExpansions = {
   background: {
     backgroundAttachment: true,
     backgroundColor: true,
@@ -145,10 +145,3 @@ var shorthandPropertyExpansions = {
     outlineColor: true,
   },
 };
-
-var CSSProperty = {
-  isUnitlessNumber: isUnitlessNumber,
-  shorthandPropertyExpansions: shorthandPropertyExpansions,
-};
-
-module.exports = CSSProperty;
diff --git a/src/renderers/dom/shared/CSSPropertyOperations.js b/src/renderers/dom/shared/CSSPropertyOperations.js
index 7495a2f836c..116a4319c67 100644
--- a/src/renderers/dom/shared/CSSPropertyOperations.js
+++ b/src/renderers/dom/shared/CSSPropertyOperations.js
@@ -11,15 +11,11 @@
 
 'use strict';
 
-var CSSProperty = require('CSSProperty');
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
-
-var dangerousStyleValue = require('dangerousStyleValue');
-
-if (__DEV__) {
-  var hyphenateStyleName = require('fbjs/lib/hyphenateStyleName');
-  var warnValidStyle = require('warnValidStyle');
-}
+import {shorthandPropertyExpansions} from 'CSSProperty';
+import ExecutionEnvironment from 'fbjs/lib/ExecutionEnvironment';
+import dangerousStyleValue from 'dangerousStyleValue';
+import hyphenateStyleName from 'fbjs/lib/hyphenateStyleName';
+import warnValidStyle from 'warnValidStyle';
 
 var hasShorthandPropertyBug = false;
 if (ExecutionEnvironment.canUseDOM) {
@@ -35,86 +31,82 @@ if (ExecutionEnvironment.canUseDOM) {
 /**
  * Operations for dealing with CSS properties.
  */
-var CSSPropertyOperations = {
-  /**
-   * This creates a string that is expected to be equivalent to the style
-   * attribute generated by server-side rendering. It by-passes warnings and
-   * security checks so it's not safe to use this value for anything other than
-   * comparison. It is only used in DEV for SSR validation.
-   */
-  createDangerousStringForStyles: function(styles) {
-    if (__DEV__) {
-      var serialized = '';
-      var delimiter = '';
-      for (var styleName in styles) {
-        if (!styles.hasOwnProperty(styleName)) {
-          continue;
-        }
-        var styleValue = styles[styleName];
-        if (styleValue != null) {
-          var isCustomProperty = styleName.indexOf('--') === 0;
-          serialized += delimiter + hyphenateStyleName(styleName) + ':';
-          serialized += dangerousStyleValue(
-            styleName,
-            styleValue,
-            isCustomProperty,
-          );
 
-          delimiter = ';';
-        }
-      }
-      return serialized || null;
-    }
-  },
-
-  /**
-   * Sets the value for multiple styles on a node.  If a value is specified as
-   * '' (empty string), the corresponding style property will be unset.
-   *
-   * @param {DOMElement} node
-   * @param {object} styles
-   * @param {ReactDOMComponent} component
-   */
-  setValueForStyles: function(node, styles, component) {
-    var style = node.style;
+/**
+ * This creates a string that is expected to be equivalent to the style
+ * attribute generated by server-side rendering. It by-passes warnings and
+ * security checks so it's not safe to use this value for anything other than
+ * comparison. It is only used in DEV for SSR validation.
+ */
+export function createDangerousStringForStyles(styles) {
+  if (__DEV__) {
+    var serialized = '';
+    var delimiter = '';
     for (var styleName in styles) {
       if (!styles.hasOwnProperty(styleName)) {
         continue;
       }
-      var isCustomProperty = styleName.indexOf('--') === 0;
-      if (__DEV__) {
-        if (!isCustomProperty) {
-          warnValidStyle(styleName, styles[styleName], component);
-        }
+      var styleValue = styles[styleName];
+      if (styleValue != null) {
+        var isCustomProperty = styleName.indexOf('--') === 0;
+        serialized += delimiter + hyphenateStyleName(styleName) + ':';
+        serialized += dangerousStyleValue(
+          styleName,
+          styleValue,
+          isCustomProperty,
+        );
+
+        delimiter = ';';
       }
-      var styleValue = dangerousStyleValue(
-        styleName,
-        styles[styleName],
-        isCustomProperty,
-      );
-      if (styleName === 'float') {
-        styleName = 'cssFloat';
+    }
+    return serialized || null;
+  }
+}
+
+/**
+ * Sets the value for multiple styles on a node.  If a value is specified as
+ * '' (empty string), the corresponding style property will be unset.
+ *
+ * @param {DOMElement} node
+ * @param {object} styles
+ * @param {ReactDOMComponent} component
+ */
+export function setValueForStyles(node, styles, component) {
+  var style = node.style;
+  for (var styleName in styles) {
+    if (!styles.hasOwnProperty(styleName)) {
+      continue;
+    }
+    var isCustomProperty = styleName.indexOf('--') === 0;
+    if (__DEV__) {
+      if (!isCustomProperty) {
+        warnValidStyle(styleName, styles[styleName], component);
       }
-      if (isCustomProperty) {
-        style.setProperty(styleName, styleValue);
-      } else if (styleValue) {
-        style[styleName] = styleValue;
-      } else {
-        var expansion =
-          hasShorthandPropertyBug &&
-          CSSProperty.shorthandPropertyExpansions[styleName];
-        if (expansion) {
-          // Shorthand property that IE8 won't like unsetting, so unset each
-          // component to placate it
-          for (var individualStyleName in expansion) {
-            style[individualStyleName] = '';
-          }
-        } else {
-          style[styleName] = '';
+    }
+    var styleValue = dangerousStyleValue(
+      styleName,
+      styles[styleName],
+      isCustomProperty,
+    );
+    if (styleName === 'float') {
+      styleName = 'cssFloat';
+    }
+    if (isCustomProperty) {
+      style.setProperty(styleName, styleValue);
+    } else if (styleValue) {
+      style[styleName] = styleValue;
+    } else {
+      var expansion =
+        hasShorthandPropertyBug && shorthandPropertyExpansions[styleName];
+      if (expansion) {
+        // Shorthand property that IE8 won't like unsetting, so unset each
+        // component to placate it
+        for (var individualStyleName in expansion) {
+          style[individualStyleName] = '';
         }
+      } else {
+        style[styleName] = '';
       }
     }
-  },
-};
-
-module.exports = CSSPropertyOperations;
+  }
+}
diff --git a/src/renderers/dom/shared/DOMMarkupOperations.js b/src/renderers/dom/shared/DOMMarkupOperations.js
index 9323f718277..e1e616f7afc 100644
--- a/src/renderers/dom/shared/DOMMarkupOperations.js
+++ b/src/renderers/dom/shared/DOMMarkupOperations.js
@@ -11,22 +11,21 @@
 
 'use strict';
 
-var DOMProperty = require('DOMProperty');
-
-var quoteAttributeValueForBrowser = require('quoteAttributeValueForBrowser');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import {
+  ATTRIBUTE_NAME_CHAR,
+  ATTRIBUTE_NAME_START_CHAR,
+  ID_ATTRIBUTE_NAME,
+  ROOT_ATTRIBUTE_NAME,
+  getPropertyInfo,
+  shouldSetAttribute,
+} from 'DOMProperty';
+import quoteAttributeValueForBrowser from 'quoteAttributeValueForBrowser';
+import warning from 'fbjs/lib/warning';
 
 // isAttributeNameSafe() is currently duplicated in DOMPropertyOperations.
 // TODO: Find a better place for this.
 var VALID_ATTRIBUTE_NAME_REGEX = new RegExp(
-  '^[' +
-    DOMProperty.ATTRIBUTE_NAME_START_CHAR +
-    '][' +
-    DOMProperty.ATTRIBUTE_NAME_CHAR +
-    ']*$',
+  '^[' + ATTRIBUTE_NAME_START_CHAR + '][' + ATTRIBUTE_NAME_CHAR + ']*$',
 );
 var illegalAttributeNameCache = {};
 var validatedAttributeNameCache = {};
@@ -63,66 +62,61 @@ function shouldIgnoreValue(propertyInfo, value) {
 /**
  * Operations for dealing with DOM properties.
  */
-var DOMMarkupOperations = {
-  /**
-   * Creates markup for the ID property.
-   *
-   * @param {string} id Unescaped ID.
-   * @return {string} Markup string.
-   */
-  createMarkupForID: function(id) {
-    return (
-      DOMProperty.ID_ATTRIBUTE_NAME + '=' + quoteAttributeValueForBrowser(id)
-    );
-  },
 
-  createMarkupForRoot: function() {
-    return DOMProperty.ROOT_ATTRIBUTE_NAME + '=""';
-  },
+/**
+ * Creates markup for the ID property.
+ *
+ * @param {string} id Unescaped ID.
+ * @return {string} Markup string.
+ */
+export function createMarkupForID(id) {
+  return ID_ATTRIBUTE_NAME + '=' + quoteAttributeValueForBrowser(id);
+}
 
-  /**
-   * Creates markup for a property.
-   *
-   * @param {string} name
-   * @param {*} value
-   * @return {?string} Markup string, or null if the property was invalid.
-   */
-  createMarkupForProperty: function(name, value) {
-    var propertyInfo = DOMProperty.getPropertyInfo(name);
-    if (propertyInfo) {
-      if (shouldIgnoreValue(propertyInfo, value)) {
-        return '';
-      }
-      var attributeName = propertyInfo.attributeName;
-      if (
-        propertyInfo.hasBooleanValue ||
-        (propertyInfo.hasOverloadedBooleanValue && value === true)
-      ) {
-        return attributeName + '=""';
-      }
-      return attributeName + '=' + quoteAttributeValueForBrowser(value);
-    } else if (DOMProperty.shouldSetAttribute(name, value)) {
-      if (value == null) {
-        return '';
-      }
-      return name + '=' + quoteAttributeValueForBrowser(value);
-    }
-    return null;
-  },
+export function createMarkupForRoot() {
+  return ROOT_ATTRIBUTE_NAME + '=""';
+}
 
-  /**
-   * Creates markup for a custom property.
-   *
-   * @param {string} name
-   * @param {*} value
-   * @return {string} Markup string, or empty string if the property was invalid.
-   */
-  createMarkupForCustomAttribute: function(name, value) {
-    if (!isAttributeNameSafe(name) || value == null) {
+/**
+ * Creates markup for a property.
+ *
+ * @param {string} name
+ * @param {*} value
+ * @return {?string} Markup string, or null if the property was invalid.
+ */
+export function createMarkupForProperty(name, value) {
+  var propertyInfo = getPropertyInfo(name);
+  if (propertyInfo) {
+    if (shouldIgnoreValue(propertyInfo, value)) {
+      return '';
+    }
+    var attributeName = propertyInfo.attributeName;
+    if (
+      propertyInfo.hasBooleanValue ||
+      (propertyInfo.hasOverloadedBooleanValue && value === true)
+    ) {
+      return attributeName + '=""';
+    }
+    return attributeName + '=' + quoteAttributeValueForBrowser(value);
+  } else if (shouldSetAttribute(name, value)) {
+    if (value == null) {
       return '';
     }
     return name + '=' + quoteAttributeValueForBrowser(value);
-  },
-};
+  }
+  return null;
+}
 
-module.exports = DOMMarkupOperations;
+/**
+ * Creates markup for a custom property.
+ *
+ * @param {string} name
+ * @param {*} value
+ * @return {string} Markup string, or empty string if the property was invalid.
+ */
+export function createMarkupForCustomAttribute(name, value) {
+  if (!isAttributeNameSafe(name) || value == null) {
+    return '';
+  }
+  return name + '=' + quoteAttributeValueForBrowser(value);
+}
diff --git a/src/renderers/dom/shared/DOMNamespaces.js b/src/renderers/dom/shared/DOMNamespaces.js
index 05129b1c903..418dc4b6b61 100644
--- a/src/renderers/dom/shared/DOMNamespaces.js
+++ b/src/renderers/dom/shared/DOMNamespaces.js
@@ -15,14 +15,14 @@ const HTML_NAMESPACE = 'http://www.w3.org/1999/xhtml';
 const MATH_NAMESPACE = 'http://www.w3.org/1998/Math/MathML';
 const SVG_NAMESPACE = 'http://www.w3.org/2000/svg';
 
-const Namespaces = {
+export const Namespaces = {
   html: HTML_NAMESPACE,
   mathml: MATH_NAMESPACE,
   svg: SVG_NAMESPACE,
 };
 
 // Assumes there is no parent namespace.
-function getIntrinsicNamespace(type: string): string {
+export function getIntrinsicNamespace(type: string): string {
   switch (type) {
     case 'svg':
       return SVG_NAMESPACE;
@@ -33,7 +33,7 @@ function getIntrinsicNamespace(type: string): string {
   }
 }
 
-function getChildNamespace(
+export function getChildNamespace(
   parentNamespace: string | null,
   type: string,
 ): string {
@@ -48,7 +48,3 @@ function getChildNamespace(
   // By default, pass namespace below.
   return parentNamespace;
 }
-
-exports.Namespaces = Namespaces;
-exports.getIntrinsicNamespace = getIntrinsicNamespace;
-exports.getChildNamespace = getChildNamespace;
diff --git a/src/renderers/dom/shared/DOMProperty.js b/src/renderers/dom/shared/DOMProperty.js
index d6ddf9c3b3a..73261451752 100644
--- a/src/renderers/dom/shared/DOMProperty.js
+++ b/src/renderers/dom/shared/DOMProperty.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var invariant = require('fbjs/lib/invariant');
+import invariant from 'fbjs/lib/invariant';
 
 // These attributes should be all lowercase to allow for
 // case insensitive checks
@@ -32,42 +32,41 @@ function checkMask(value, bitmask) {
   return (value & bitmask) === bitmask;
 }
 
-var DOMPropertyInjection = {
-  /**
-   * Mapping from normalized, camelcased property names to a configuration that
-   * specifies how the associated DOM property should be accessed or rendered.
-   */
-  MUST_USE_PROPERTY: 0x1,
-  HAS_BOOLEAN_VALUE: 0x4,
-  HAS_NUMERIC_VALUE: 0x8,
-  HAS_POSITIVE_NUMERIC_VALUE: 0x10 | 0x8,
-  HAS_OVERLOADED_BOOLEAN_VALUE: 0x20,
-
-  /**
-   * Inject some specialized knowledge about the DOM. This takes a config object
-   * with the following properties:
-   *
-   * Properties: object mapping DOM property name to one of the
-   * DOMPropertyInjection constants or null. If your attribute isn't in here,
-   * it won't get written to the DOM.
-   *
-   * DOMAttributeNames: object mapping React attribute name to the DOM
-   * attribute name. Attribute names not specified use the **lowercase**
-   * normalized name.
-   *
-   * DOMAttributeNamespaces: object mapping React attribute name to the DOM
-   * attribute namespace URL. (Attribute names not specified use no namespace.)
-   *
-   * DOMPropertyNames: similar to DOMAttributeNames but for DOM properties.
-   * Property names not specified use the normalized name.
-   *
-   * DOMMutationMethods: Properties that require special mutation methods. If
-   * `value` is undefined, the mutation method should unset the property.
-   *
-   * @param {object} domPropertyConfig the config as described above.
-   */
-  injectDOMPropertyConfig: function(domPropertyConfig) {
-    var Injection = DOMPropertyInjection;
+/**
+ * Mapping from normalized, camelcased property names to a configuration that
+ * specifies how the associated DOM property should be accessed or rendered.
+ */
+export const MUST_USE_PROPERTY = 0x1;
+export const HAS_BOOLEAN_VALUE = 0x4;
+export const HAS_NUMERIC_VALUE = 0x8;
+export const HAS_POSITIVE_NUMERIC_VALUE = 0x10 | 0x8;
+export const HAS_OVERLOADED_BOOLEAN_VALUE = 0x20;
+
+/**
+ * Inject some specialized knowledge about the DOM. This takes a config object
+ * with the following properties:
+ *
+ * Properties: object mapping DOM property name to one of the
+ * constants above or null. If your attribute isn't in here,
+ * it won't get written to the DOM.
+ *
+ * DOMAttributeNames: object mapping React attribute name to the DOM
+ * attribute name. Attribute names not specified use the **lowercase**
+ * normalized name.
+ *
+ * DOMAttributeNamespaces: object mapping React attribute name to the DOM
+ * attribute namespace URL. (Attribute names not specified use no namespace.)
+ *
+ * DOMPropertyNames: similar to DOMAttributeNames but for DOM properties.
+ * Property names not specified use the normalized name.
+ *
+ * DOMMutationMethods: Properties that require special mutation methods. If
+ * `value` is undefined, the mutation method should unset the property.
+ *
+ * @param {object} domPropertyConfig the config as described above.
+ */
+export const injection = {
+  injectDOMPropertyConfig(domPropertyConfig) {
     var Properties = domPropertyConfig.Properties || {};
     var DOMAttributeNamespaces = domPropertyConfig.DOMAttributeNamespaces || {};
     var DOMAttributeNames = domPropertyConfig.DOMAttributeNames || {};
@@ -75,7 +74,7 @@ var DOMPropertyInjection = {
 
     for (var propName in Properties) {
       invariant(
-        !DOMProperty.properties.hasOwnProperty(propName),
+        !properties.hasOwnProperty(propName),
         "injectDOMPropertyConfig(...): You're trying to inject DOM property " +
           "'%s' which has already been injected. You may be accidentally " +
           'injecting the same DOM property config twice, or you may be ' +
@@ -92,16 +91,16 @@ var DOMPropertyInjection = {
         propertyName: propName,
         mutationMethod: null,
 
-        mustUseProperty: checkMask(propConfig, Injection.MUST_USE_PROPERTY),
-        hasBooleanValue: checkMask(propConfig, Injection.HAS_BOOLEAN_VALUE),
-        hasNumericValue: checkMask(propConfig, Injection.HAS_NUMERIC_VALUE),
+        mustUseProperty: checkMask(propConfig, MUST_USE_PROPERTY),
+        hasBooleanValue: checkMask(propConfig, HAS_BOOLEAN_VALUE),
+        hasNumericValue: checkMask(propConfig, HAS_NUMERIC_VALUE),
         hasPositiveNumericValue: checkMask(
           propConfig,
-          Injection.HAS_POSITIVE_NUMERIC_VALUE,
+          HAS_POSITIVE_NUMERIC_VALUE,
         ),
         hasOverloadedBooleanValue: checkMask(
           propConfig,
-          Injection.HAS_OVERLOADED_BOOLEAN_VALUE,
+          HAS_OVERLOADED_BOOLEAN_VALUE,
         ),
       };
       invariant(
@@ -132,16 +131,11 @@ var DOMPropertyInjection = {
       // without case-sensitivity. This allows the whitelist to pick up
       // `allowfullscreen`, which should be written using the property configuration
       // for `allowFullscreen`
-      DOMProperty.properties[propName] = propertyInfo;
+      properties[propName] = propertyInfo;
     }
   },
 };
 
-/* eslint-disable max-len */
-var ATTRIBUTE_NAME_START_CHAR =
-  ':A-Z_a-z\\u00C0-\\u00D6\\u00D8-\\u00F6\\u00F8-\\u02FF\\u0370-\\u037D\\u037F-\\u1FFF\\u200C-\\u200D\\u2070-\\u218F\\u2C00-\\u2FEF\\u3001-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFFD';
-/* eslint-enable max-len */
-
 /**
  * DOMProperty exports lookup objects that can be used like functions:
  *
@@ -155,15 +149,17 @@ var ATTRIBUTE_NAME_START_CHAR =
  * @see http://jsperf.com/key-exists
  * @see http://jsperf.com/key-missing
  */
-var DOMProperty = {
-  ID_ATTRIBUTE_NAME: 'data-reactid',
-  ROOT_ATTRIBUTE_NAME: 'data-reactroot',
 
-  ATTRIBUTE_NAME_START_CHAR: ATTRIBUTE_NAME_START_CHAR,
-  ATTRIBUTE_NAME_CHAR: ATTRIBUTE_NAME_START_CHAR +
-    '\\-.0-9\\u00B7\\u0300-\\u036F\\u203F-\\u2040',
+export const ID_ATTRIBUTE_NAME = 'data-reactid';
+export const ROOT_ATTRIBUTE_NAME = 'data-reactroot';
+/* eslint-disable max-len */
+export const ATTRIBUTE_NAME_START_CHAR =
+  ':A-Z_a-z\\u00C0-\\u00D6\\u00D8-\\u00F6\\u00F8-\\u02FF\\u0370-\\u037D\\u037F-\\u1FFF\\u200C-\\u200D\\u2070-\\u218F\\u2C00-\\u2FEF\\u3001-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFFD';
+/* eslint-enable max-len */
+export const ATTRIBUTE_NAME_CHAR =
+  ATTRIBUTE_NAME_START_CHAR + '\\-.0-9\\u00B7\\u0300-\\u036F\\u203F-\\u2040';
 
-  /**
+/**
    * Map from property "standard name" to an object with info about how to set
    * the property in the DOM. Each object contains:
    *
@@ -191,64 +187,57 @@ var DOMProperty = {
    *   Removed when strictly equal to false; present without a value when
    *   strictly equal to true; present with a value otherwise.
    */
-  properties: {},
+export const properties = {};
 
-  /**
+/**
    * Checks whether a property name is a writeable attribute.
    * @method
    */
-  shouldSetAttribute: function(name, value) {
-    if (DOMProperty.isReservedProp(name)) {
-      return false;
-    }
+export function shouldSetAttribute(name, value) {
+  if (isReservedProp(name)) {
+    return false;
+  }
 
-    if (value === null) {
-      return true;
-    }
+  if (value === null) {
+    return true;
+  }
 
-    var lowerCased = name.toLowerCase();
+  var lowerCased = name.toLowerCase();
 
-    var propertyInfo = DOMProperty.properties[name];
+  var propertyInfo = properties[name];
 
-    switch (typeof value) {
-      case 'boolean':
-        if (propertyInfo) {
-          return true;
-        }
-        var prefix = lowerCased.slice(0, 5);
-        return prefix === 'data-' || prefix === 'aria-';
-      case 'undefined':
-      case 'number':
-      case 'string':
-        return true;
-      case 'object':
+  switch (typeof value) {
+    case 'boolean':
+      if (propertyInfo) {
         return true;
-      default:
-        // function, symbol
-        return false;
-    }
-  },
-
-  getPropertyInfo(name) {
-    return DOMProperty.properties.hasOwnProperty(name)
-      ? DOMProperty.properties[name]
-      : null;
-  },
-
-  /**
-   * Checks to see if a property name is within the list of properties
-   * reserved for internal React operations. These properties should
-   * not be set on an HTML element.
-   *
-   * @private
-   * @param {string} name
-   * @return {boolean} If the name is within reserved props
-   */
-  isReservedProp(name) {
-    return RESERVED_PROPS.hasOwnProperty(name.toLowerCase());
-  },
+      }
+      var prefix = lowerCased.slice(0, 5);
+      return prefix === 'data-' || prefix === 'aria-';
+    case 'undefined':
+    case 'number':
+    case 'string':
+      return true;
+    case 'object':
+      return true;
+    default:
+      // function, symbol
+      return false;
+  }
+}
 
-  injection: DOMPropertyInjection,
-};
+export function getPropertyInfo(name) {
+  return properties.hasOwnProperty(name) ? properties[name] : null;
+}
 
-module.exports = DOMProperty;
+/**
+ * Checks to see if a property name is within the list of properties
+ * reserved for internal React operations. These properties should
+ * not be set on an HTML element.
+ *
+ * @private
+ * @param {string} name
+ * @return {boolean} If the name is within reserved props
+ */
+export function isReservedProp(name) {
+  return RESERVED_PROPS.hasOwnProperty(name.toLowerCase());
+}
diff --git a/src/renderers/dom/shared/DOMPropertyOperations.js b/src/renderers/dom/shared/DOMPropertyOperations.js
index 96dead745ba..5f8b266861d 100644
--- a/src/renderers/dom/shared/DOMPropertyOperations.js
+++ b/src/renderers/dom/shared/DOMPropertyOperations.js
@@ -11,22 +11,20 @@
 
 'use strict';
 
-var DOMProperty = require('DOMProperty');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactInstrumentation = require('ReactInstrumentation');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import {
+  ATTRIBUTE_NAME_START_CHAR,
+  ATTRIBUTE_NAME_CHAR,
+  ID_ATTRIBUTE_NAME,
+  ROOT_ATTRIBUTE_NAME,
+  getPropertyInfo,
+  shouldSetAttribute,
+} from 'DOMProperty';
+import warning from 'fbjs/lib/warning';
 
 // isAttributeNameSafe() is currently duplicated in DOMMarkupOperations.
 // TODO: Find a better place for this.
 var VALID_ATTRIBUTE_NAME_REGEX = new RegExp(
-  '^[' +
-    DOMProperty.ATTRIBUTE_NAME_START_CHAR +
-    '][' +
-    DOMProperty.ATTRIBUTE_NAME_CHAR +
-    ']*$',
+  '^[' + ATTRIBUTE_NAME_START_CHAR + '][' + ATTRIBUTE_NAME_CHAR + ']*$',
 );
 var illegalAttributeNameCache = {};
 var validatedAttributeNameCache = {};
@@ -63,226 +61,198 @@ function shouldIgnoreValue(propertyInfo, value) {
 /**
  * Operations for dealing with DOM properties.
  */
-var DOMPropertyOperations = {
-  setAttributeForID: function(node, id) {
-    node.setAttribute(DOMProperty.ID_ATTRIBUTE_NAME, id);
-  },
 
-  setAttributeForRoot: function(node) {
-    node.setAttribute(DOMProperty.ROOT_ATTRIBUTE_NAME, '');
-  },
+export function setAttributeForID(node, id) {
+  node.setAttribute(ID_ATTRIBUTE_NAME, id);
+}
 
-  /**
-   * Get the value for a property on a node. Only used in DEV for SSR validation.
-   * The "expected" argument is used as a hint of what the expected value is.
-   * Some properties have multiple equivalent values.
-   */
-  getValueForProperty: function(node, name, expected) {
-    if (__DEV__) {
-      var propertyInfo = DOMProperty.getPropertyInfo(name);
-      if (propertyInfo) {
-        var mutationMethod = propertyInfo.mutationMethod;
-        if (mutationMethod || propertyInfo.mustUseProperty) {
-          return node[propertyInfo.propertyName];
-        } else {
-          var attributeName = propertyInfo.attributeName;
+export function setAttributeForRoot(node) {
+  node.setAttribute(ROOT_ATTRIBUTE_NAME, '');
+}
+
+/**
+ * Get the value for a property on a node. Only used in DEV for SSR validation.
+ * The "expected" argument is used as a hint of what the expected value is.
+ * Some properties have multiple equivalent values.
+ */
+export function getValueForProperty(node, name, expected) {
+  if (__DEV__) {
+    var propertyInfo = getPropertyInfo(name);
+    if (propertyInfo) {
+      var mutationMethod = propertyInfo.mutationMethod;
+      if (mutationMethod || propertyInfo.mustUseProperty) {
+        return node[propertyInfo.propertyName];
+      } else {
+        var attributeName = propertyInfo.attributeName;
 
-          var stringValue = null;
+        var stringValue = null;
 
-          if (propertyInfo.hasOverloadedBooleanValue) {
-            if (node.hasAttribute(attributeName)) {
-              var value = node.getAttribute(attributeName);
-              if (value === '') {
-                return true;
-              }
-              if (shouldIgnoreValue(propertyInfo, expected)) {
-                return value;
-              }
-              if (value === '' + expected) {
-                return expected;
-              }
-              return value;
+        if (propertyInfo.hasOverloadedBooleanValue) {
+          if (node.hasAttribute(attributeName)) {
+            var value = node.getAttribute(attributeName);
+            if (value === '') {
+              return true;
             }
-          } else if (node.hasAttribute(attributeName)) {
             if (shouldIgnoreValue(propertyInfo, expected)) {
-              // We had an attribute but shouldn't have had one, so read it
-              // for the error message.
-              return node.getAttribute(attributeName);
+              return value;
             }
-            if (propertyInfo.hasBooleanValue) {
-              // If this was a boolean, it doesn't matter what the value is
-              // the fact that we have it is the same as the expected.
+            if (value === '' + expected) {
               return expected;
             }
-            // Even if this property uses a namespace we use getAttribute
-            // because we assume its namespaced name is the same as our config.
-            // To use getAttributeNS we need the local name which we don't have
-            // in our config atm.
-            stringValue = node.getAttribute(attributeName);
+            return value;
           }
-
+        } else if (node.hasAttribute(attributeName)) {
           if (shouldIgnoreValue(propertyInfo, expected)) {
-            return stringValue === null ? expected : stringValue;
-          } else if (stringValue === '' + expected) {
+            // We had an attribute but shouldn't have had one, so read it
+            // for the error message.
+            return node.getAttribute(attributeName);
+          }
+          if (propertyInfo.hasBooleanValue) {
+            // If this was a boolean, it doesn't matter what the value is
+            // the fact that we have it is the same as the expected.
             return expected;
-          } else {
-            return stringValue;
           }
+          // Even if this property uses a namespace we use getAttribute
+          // because we assume its namespaced name is the same as our config.
+          // To use getAttributeNS we need the local name which we don't have
+          // in our config atm.
+          stringValue = node.getAttribute(attributeName);
         }
-      }
-    }
-  },
-
-  /**
-   * Get the value for a attribute on a node. Only used in DEV for SSR validation.
-   * The third argument is used as a hint of what the expected value is. Some
-   * attributes have multiple equivalent values.
-   */
-  getValueForAttribute: function(node, name, expected) {
-    if (__DEV__) {
-      if (!isAttributeNameSafe(name)) {
-        return;
-      }
-      if (!node.hasAttribute(name)) {
-        return expected === undefined ? undefined : null;
-      }
-      var value = node.getAttribute(name);
-      if (value === '' + expected) {
-        return expected;
-      }
-      return value;
-    }
-  },
-
-  /**
-   * Sets the value for a property on a node.
-   *
-   * @param {DOMElement} node
-   * @param {string} name
-   * @param {*} value
-   */
-  setValueForProperty: function(node, name, value) {
-    var propertyInfo = DOMProperty.getPropertyInfo(name);
 
-    if (propertyInfo && DOMProperty.shouldSetAttribute(name, value)) {
-      var mutationMethod = propertyInfo.mutationMethod;
-      if (mutationMethod) {
-        mutationMethod(node, value);
-      } else if (shouldIgnoreValue(propertyInfo, value)) {
-        DOMPropertyOperations.deleteValueForProperty(node, name);
-        return;
-      } else if (propertyInfo.mustUseProperty) {
-        // Contrary to `setAttribute`, object properties are properly
-        // `toString`ed by IE8/9.
-        node[propertyInfo.propertyName] = value;
-      } else {
-        var attributeName = propertyInfo.attributeName;
-        var namespace = propertyInfo.attributeNamespace;
-        // `setAttribute` with objects becomes only `[object]` in IE8/9,
-        // ('' + value) makes it output the correct toString()-value.
-        if (namespace) {
-          node.setAttributeNS(namespace, attributeName, '' + value);
-        } else if (
-          propertyInfo.hasBooleanValue ||
-          (propertyInfo.hasOverloadedBooleanValue && value === true)
-        ) {
-          node.setAttribute(attributeName, '');
+        if (shouldIgnoreValue(propertyInfo, expected)) {
+          return stringValue === null ? expected : stringValue;
+        } else if (stringValue === '' + expected) {
+          return expected;
         } else {
-          node.setAttribute(attributeName, '' + value);
+          return stringValue;
         }
       }
-    } else {
-      DOMPropertyOperations.setValueForAttribute(
-        node,
-        name,
-        DOMProperty.shouldSetAttribute(name, value) ? value : null,
-      );
-      return;
     }
+  }
+}
 
-    if (__DEV__) {
-      var payload = {};
-      payload[name] = value;
-      ReactInstrumentation.debugTool.onHostOperation({
-        instanceID: ReactDOMComponentTree.getInstanceFromNode(node)._debugID,
-        type: 'update attribute',
-        payload: payload,
-      });
-    }
-  },
-
-  setValueForAttribute: function(node, name, value) {
+/**
+ * Get the value for a attribute on a node. Only used in DEV for SSR validation.
+ * The third argument is used as a hint of what the expected value is. Some
+ * attributes have multiple equivalent values.
+ */
+export function getValueForAttribute(node, name, expected) {
+  if (__DEV__) {
     if (!isAttributeNameSafe(name)) {
       return;
     }
-    if (value == null) {
-      node.removeAttribute(name);
-    } else {
-      node.setAttribute(name, '' + value);
+    if (!node.hasAttribute(name)) {
+      return expected === undefined ? undefined : null;
     }
+    var value = node.getAttribute(name);
+    if (value === '' + expected) {
+      return expected;
+    }
+    return value;
+  }
+}
+
+/**
+ * Sets the value for a property on a node.
+ *
+ * @param {DOMElement} node
+ * @param {string} name
+ * @param {*} value
+ */
+export function setValueForProperty(node, name, value) {
+  var propertyInfo = getPropertyInfo(name);
 
-    if (__DEV__) {
-      var payload = {};
-      payload[name] = value;
-      ReactInstrumentation.debugTool.onHostOperation({
-        instanceID: ReactDOMComponentTree.getInstanceFromNode(node)._debugID,
-        type: 'update attribute',
-        payload: payload,
-      });
+  if (propertyInfo && shouldSetAttribute(name, value)) {
+    var mutationMethod = propertyInfo.mutationMethod;
+    if (mutationMethod) {
+      mutationMethod(node, value);
+    } else if (shouldIgnoreValue(propertyInfo, value)) {
+      deleteValueForProperty(node, name);
+      return;
+    } else if (propertyInfo.mustUseProperty) {
+      // Contrary to `setAttribute`, object properties are properly
+      // `toString`ed by IE8/9.
+      node[propertyInfo.propertyName] = value;
+    } else {
+      var attributeName = propertyInfo.attributeName;
+      var namespace = propertyInfo.attributeNamespace;
+      // `setAttribute` with objects becomes only `[object]` in IE8/9,
+      // ('' + value) makes it output the correct toString()-value.
+      if (namespace) {
+        node.setAttributeNS(namespace, attributeName, '' + value);
+      } else if (
+        propertyInfo.hasBooleanValue ||
+        (propertyInfo.hasOverloadedBooleanValue && value === true)
+      ) {
+        node.setAttribute(attributeName, '');
+      } else {
+        node.setAttribute(attributeName, '' + value);
+      }
     }
-  },
+  } else {
+    setValueForAttribute(
+      node,
+      name,
+      shouldSetAttribute(name, value) ? value : null,
+    );
+    return;
+  }
 
-  /**
-   * Deletes an attributes from a node.
-   *
-   * @param {DOMElement} node
-   * @param {string} name
-   */
-  deleteValueForAttribute: function(node, name) {
+  if (__DEV__) {
+    var payload = {};
+    payload[name] = value;
+  }
+}
+
+export function setValueForAttribute(node, name, value) {
+  if (!isAttributeNameSafe(name)) {
+    return;
+  }
+  if (value == null) {
     node.removeAttribute(name);
-    if (__DEV__) {
-      ReactInstrumentation.debugTool.onHostOperation({
-        instanceID: ReactDOMComponentTree.getInstanceFromNode(node)._debugID,
-        type: 'remove attribute',
-        payload: name,
-      });
-    }
-  },
+  } else {
+    node.setAttribute(name, '' + value);
+  }
 
-  /**
-   * Deletes the value for a property on a node.
-   *
-   * @param {DOMElement} node
-   * @param {string} name
-   */
-  deleteValueForProperty: function(node, name) {
-    var propertyInfo = DOMProperty.getPropertyInfo(name);
-    if (propertyInfo) {
-      var mutationMethod = propertyInfo.mutationMethod;
-      if (mutationMethod) {
-        mutationMethod(node, undefined);
-      } else if (propertyInfo.mustUseProperty) {
-        var propName = propertyInfo.propertyName;
-        if (propertyInfo.hasBooleanValue) {
-          node[propName] = false;
-        } else {
-          node[propName] = '';
-        }
+  if (__DEV__) {
+    var payload = {};
+    payload[name] = value;
+  }
+}
+
+/**
+ * Deletes an attributes from a node.
+ *
+ * @param {DOMElement} node
+ * @param {string} name
+ */
+export function deleteValueForAttribute(node, name) {
+  node.removeAttribute(name);
+}
+
+/**
+ * Deletes the value for a property on a node.
+ *
+ * @param {DOMElement} node
+ * @param {string} name
+ */
+export function deleteValueForProperty(node, name) {
+  var propertyInfo = getPropertyInfo(name);
+  if (propertyInfo) {
+    var mutationMethod = propertyInfo.mutationMethod;
+    if (mutationMethod) {
+      mutationMethod(node, undefined);
+    } else if (propertyInfo.mustUseProperty) {
+      var propName = propertyInfo.propertyName;
+      if (propertyInfo.hasBooleanValue) {
+        node[propName] = false;
       } else {
-        node.removeAttribute(propertyInfo.attributeName);
+        node[propName] = '';
       }
     } else {
-      node.removeAttribute(name);
-    }
-
-    if (__DEV__) {
-      ReactInstrumentation.debugTool.onHostOperation({
-        instanceID: ReactDOMComponentTree.getInstanceFromNode(node)._debugID,
-        type: 'remove attribute',
-        payload: name,
-      });
+      node.removeAttribute(propertyInfo.attributeName);
     }
-  },
-};
-
-module.exports = DOMPropertyOperations;
+  } else {
+    node.removeAttribute(name);
+  }
+}
diff --git a/src/renderers/dom/shared/HTMLDOMPropertyConfig.js b/src/renderers/dom/shared/HTMLDOMPropertyConfig.js
index ed3808c7f7d..5f953f95b7c 100644
--- a/src/renderers/dom/shared/HTMLDOMPropertyConfig.js
+++ b/src/renderers/dom/shared/HTMLDOMPropertyConfig.js
@@ -11,15 +11,13 @@
 
 'use strict';
 
-var DOMProperty = require('DOMProperty');
-
-var MUST_USE_PROPERTY = DOMProperty.injection.MUST_USE_PROPERTY;
-var HAS_BOOLEAN_VALUE = DOMProperty.injection.HAS_BOOLEAN_VALUE;
-var HAS_NUMERIC_VALUE = DOMProperty.injection.HAS_NUMERIC_VALUE;
-var HAS_POSITIVE_NUMERIC_VALUE =
-  DOMProperty.injection.HAS_POSITIVE_NUMERIC_VALUE;
-var HAS_OVERLOADED_BOOLEAN_VALUE =
-  DOMProperty.injection.HAS_OVERLOADED_BOOLEAN_VALUE;
+import {
+  MUST_USE_PROPERTY,
+  HAS_BOOLEAN_VALUE,
+  HAS_NUMERIC_VALUE,
+  HAS_POSITIVE_NUMERIC_VALUE,
+  HAS_OVERLOADED_BOOLEAN_VALUE,
+} from 'DOMProperty';
 
 var HTMLDOMPropertyConfig = {
   // When adding attributes to this list, be sure to also add them to
@@ -128,4 +126,4 @@ var HTMLDOMPropertyConfig = {
   },
 };
 
-module.exports = HTMLDOMPropertyConfig;
+export default HTMLDOMPropertyConfig;
diff --git a/src/renderers/dom/shared/HTMLNodeType.js b/src/renderers/dom/shared/HTMLNodeType.js
index 35566be1732..5c0e84d8554 100644
--- a/src/renderers/dom/shared/HTMLNodeType.js
+++ b/src/renderers/dom/shared/HTMLNodeType.js
@@ -14,13 +14,8 @@
 /**
  * HTML nodeType values that represent the type of the node
  */
-
-var HTMLNodeType = {
-  ELEMENT_NODE: 1,
-  TEXT_NODE: 3,
-  COMMENT_NODE: 8,
-  DOCUMENT_NODE: 9,
-  DOCUMENT_FRAGMENT_NODE: 11,
-};
-
-module.exports = HTMLNodeType;
+export const ELEMENT_NODE = 1;
+export const TEXT_NODE = 3;
+export const COMMENT_NODE = 8;
+export const DOCUMENT_NODE = 9;
+export const DOCUMENT_FRAGMENT_NODE = 11;
diff --git a/src/renderers/dom/shared/ReactBrowserEventEmitter.js b/src/renderers/dom/shared/ReactBrowserEventEmitter.js
index 1c2661b57f9..6bed5ea28c3 100644
--- a/src/renderers/dom/shared/ReactBrowserEventEmitter.js
+++ b/src/renderers/dom/shared/ReactBrowserEventEmitter.js
@@ -11,12 +11,16 @@
 
 'use strict';
 
-var EventPluginRegistry = require('EventPluginRegistry');
-var ReactDOMEventListener = require('ReactDOMEventListener');
-var ReactEventEmitterMixin = require('ReactEventEmitterMixin');
-
-var isEventSupported = require('isEventSupported');
-var {topLevelTypes} = require('BrowserEventConstants');
+import {registrationNameDependencies} from 'EventPluginRegistry';
+import {
+  setEnabled as setEventListenerEnabled,
+  isEnabled as isEventListenerEnabled,
+  trapBubbledEvent,
+  trapCapturedEvent,
+} from 'ReactDOMEventListener';
+import {handleTopLevel} from 'ReactEventEmitterMixin';
+import isEventSupported from 'isEventSupported';
+import {topLevelTypes} from 'BrowserEventConstants';
 
 /**
  * Summary of `ReactBrowserEventEmitter` event handling:
@@ -92,153 +96,101 @@ function getListeningForDocument(mountAt) {
   return alreadyListeningTo[mountAt[topListenersIDKey]];
 }
 
-var ReactBrowserEventEmitter = Object.assign({}, ReactEventEmitterMixin, {
-  /**
-   * Sets whether or not any created callbacks should be enabled.
-   *
-   * @param {boolean} enabled True if callbacks should be enabled.
-   */
-  setEnabled: function(enabled) {
-    if (ReactDOMEventListener) {
-      ReactDOMEventListener.setEnabled(enabled);
-    }
-  },
-
-  /**
-   * @return {boolean} True if callbacks are enabled.
-   */
-  isEnabled: function() {
-    return !!(ReactDOMEventListener && ReactDOMEventListener.isEnabled());
-  },
+export {handleTopLevel};
 
-  /**
-   * We listen for bubbled touch events on the document object.
-   *
-   * Firefox v8.01 (and possibly others) exhibited strange behavior when
-   * mounting `onmousemove` events at some node that was not the document
-   * element. The symptoms were that if your mouse is not moving over something
-   * contained within that mount point (for example on the background) the
-   * top-level listeners for `onmousemove` won't be called. However, if you
-   * register the `mousemove` on the document object, then it will of course
-   * catch all `mousemove`s. This along with iOS quirks, justifies restricting
-   * top-level listeners to the document object only, at least for these
-   * movement types of events and possibly all events.
-   *
-   * @see http://www.quirksmode.org/blog/archives/2010/09/click_event_del.html
-   *
-   * Also, `keyup`/`keypress`/`keydown` do not bubble to the window on IE, but
-   * they bubble to document.
-   *
-   * @param {string} registrationName Name of listener (e.g. `onClick`).
-   * @param {object} contentDocumentHandle Document which owns the container
-   */
-  listenTo: function(registrationName, contentDocumentHandle) {
-    var mountAt = contentDocumentHandle;
-    var isListening = getListeningForDocument(mountAt);
-    var dependencies =
-      EventPluginRegistry.registrationNameDependencies[registrationName];
+/**
+ * Sets whether or not any created callbacks should be enabled.
+ *
+ * @param {boolean} enabled True if callbacks should be enabled.
+ */
+export function setEnabled(enabled) {
+  setEventListenerEnabled(enabled);
+}
 
-    for (var i = 0; i < dependencies.length; i++) {
-      var dependency = dependencies[i];
-      if (
-        !(isListening.hasOwnProperty(dependency) && isListening[dependency])
-      ) {
-        if (dependency === 'topWheel') {
-          if (isEventSupported('wheel')) {
-            ReactDOMEventListener.trapBubbledEvent(
-              'topWheel',
-              'wheel',
-              mountAt,
-            );
-          } else if (isEventSupported('mousewheel')) {
-            ReactDOMEventListener.trapBubbledEvent(
-              'topWheel',
-              'mousewheel',
-              mountAt,
-            );
-          } else {
-            // Firefox needs to capture a different mouse scroll event.
-            // @see http://www.quirksmode.org/dom/events/tests/scroll.html
-            ReactDOMEventListener.trapBubbledEvent(
-              'topWheel',
-              'DOMMouseScroll',
-              mountAt,
-            );
-          }
-        } else if (dependency === 'topScroll') {
-          ReactDOMEventListener.trapCapturedEvent(
-            'topScroll',
-            'scroll',
-            mountAt,
-          );
-        } else if (dependency === 'topFocus' || dependency === 'topBlur') {
-          ReactDOMEventListener.trapCapturedEvent('topFocus', 'focus', mountAt);
-          ReactDOMEventListener.trapCapturedEvent('topBlur', 'blur', mountAt);
+/**
+ * @return {boolean} True if callbacks are enabled.
+ */
+export function isEnabled() {
+  return !!isEventListenerEnabled();
+}
 
-          // to make sure blur and focus event listeners are only attached once
-          isListening.topBlur = true;
-          isListening.topFocus = true;
-        } else if (dependency === 'topCancel') {
-          if (isEventSupported('cancel', true)) {
-            ReactDOMEventListener.trapCapturedEvent(
-              'topCancel',
-              'cancel',
-              mountAt,
-            );
-          }
-          isListening.topCancel = true;
-        } else if (dependency === 'topClose') {
-          if (isEventSupported('close', true)) {
-            ReactDOMEventListener.trapCapturedEvent(
-              'topClose',
-              'close',
-              mountAt,
-            );
-          }
-          isListening.topClose = true;
-        } else if (topLevelTypes.hasOwnProperty(dependency)) {
-          ReactDOMEventListener.trapBubbledEvent(
-            dependency,
-            topLevelTypes[dependency],
-            mountAt,
-          );
+/**
+ * We listen for bubbled touch events on the document object.
+ *
+ * Firefox v8.01 (and possibly others) exhibited strange behavior when
+ * mounting `onmousemove` events at some node that was not the document
+ * element. The symptoms were that if your mouse is not moving over something
+ * contained within that mount point (for example on the background) the
+ * top-level listeners for `onmousemove` won't be called. However, if you
+ * register the `mousemove` on the document object, then it will of course
+ * catch all `mousemove`s. This along with iOS quirks, justifies restricting
+ * top-level listeners to the document object only, at least for these
+ * movement types of events and possibly all events.
+ *
+ * @see http://www.quirksmode.org/blog/archives/2010/09/click_event_del.html
+ *
+ * Also, `keyup`/`keypress`/`keydown` do not bubble to the window on IE, but
+ * they bubble to document.
+ *
+ * @param {string} registrationName Name of listener (e.g. `onClick`).
+ * @param {object} contentDocumentHandle Document which owns the container
+ */
+export function listenTo(registrationName, contentDocumentHandle) {
+  var mountAt = contentDocumentHandle;
+  var isListening = getListeningForDocument(mountAt);
+  var dependencies = registrationNameDependencies[registrationName];
+
+  for (var i = 0; i < dependencies.length; i++) {
+    var dependency = dependencies[i];
+    if (!(isListening.hasOwnProperty(dependency) && isListening[dependency])) {
+      if (dependency === 'topWheel') {
+        if (isEventSupported('wheel')) {
+          trapBubbledEvent('topWheel', 'wheel', mountAt);
+        } else if (isEventSupported('mousewheel')) {
+          trapBubbledEvent('topWheel', 'mousewheel', mountAt);
+        } else {
+          // Firefox needs to capture a different mouse scroll event.
+          // @see http://www.quirksmode.org/dom/events/tests/scroll.html
+          trapBubbledEvent('topWheel', 'DOMMouseScroll', mountAt);
         }
-
-        isListening[dependency] = true;
+      } else if (dependency === 'topScroll') {
+        trapCapturedEvent('topScroll', 'scroll', mountAt);
+      } else if (dependency === 'topFocus' || dependency === 'topBlur') {
+        trapCapturedEvent('topFocus', 'focus', mountAt);
+        trapCapturedEvent('topBlur', 'blur', mountAt);
+
+        // to make sure blur and focus event listeners are only attached once
+        isListening.topBlur = true;
+        isListening.topFocus = true;
+      } else if (dependency === 'topCancel') {
+        if (isEventSupported('cancel', true)) {
+          trapCapturedEvent('topCancel', 'cancel', mountAt);
+        }
+        isListening.topCancel = true;
+      } else if (dependency === 'topClose') {
+        if (isEventSupported('close', true)) {
+          trapCapturedEvent('topClose', 'close', mountAt);
+        }
+        isListening.topClose = true;
+      } else if (topLevelTypes.hasOwnProperty(dependency)) {
+        trapBubbledEvent(dependency, topLevelTypes[dependency], mountAt);
       }
-    }
-  },
 
-  isListeningToAllDependencies: function(registrationName, mountAt) {
-    var isListening = getListeningForDocument(mountAt);
-    var dependencies =
-      EventPluginRegistry.registrationNameDependencies[registrationName];
-    for (var i = 0; i < dependencies.length; i++) {
-      var dependency = dependencies[i];
-      if (
-        !(isListening.hasOwnProperty(dependency) && isListening[dependency])
-      ) {
-        return false;
-      }
+      isListening[dependency] = true;
     }
-    return true;
-  },
-
-  trapBubbledEvent: function(topLevelType, handlerBaseName, handle) {
-    return ReactDOMEventListener.trapBubbledEvent(
-      topLevelType,
-      handlerBaseName,
-      handle,
-    );
-  },
+  }
+}
 
-  trapCapturedEvent: function(topLevelType, handlerBaseName, handle) {
-    return ReactDOMEventListener.trapCapturedEvent(
-      topLevelType,
-      handlerBaseName,
-      handle,
-    );
-  },
-});
+export function isListeningToAllDependencies(registrationName, mountAt) {
+  var isListening = getListeningForDocument(mountAt);
+  var dependencies = registrationNameDependencies[registrationName];
+  for (var i = 0; i < dependencies.length; i++) {
+    var dependency = dependencies[i];
+    if (!(isListening.hasOwnProperty(dependency) && isListening[dependency])) {
+      return false;
+    }
+  }
+  return true;
+}
 
-module.exports = ReactBrowserEventEmitter;
+export {trapBubbledEvent, trapCapturedEvent};
diff --git a/src/renderers/dom/shared/ReactDOMClientInjection.js b/src/renderers/dom/shared/ReactDOMClientInjection.js
index dc929517f41..f763c455008 100644
--- a/src/renderers/dom/shared/ReactDOMClientInjection.js
+++ b/src/renderers/dom/shared/ReactDOMClientInjection.js
@@ -11,36 +11,34 @@
 
 'use strict';
 
-var BeforeInputEventPlugin = require('BeforeInputEventPlugin');
-var ChangeEventPlugin = require('ChangeEventPlugin');
-var DOMEventPluginOrder = require('DOMEventPluginOrder');
-var EnterLeaveEventPlugin = require('EnterLeaveEventPlugin');
-var EventPluginHub = require('EventPluginHub');
-var EventPluginUtils = require('EventPluginUtils');
-var ReactBrowserEventEmitter = require('ReactBrowserEventEmitter');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactDOMEventListener = require('ReactDOMEventListener');
-var SelectEventPlugin = require('SelectEventPlugin');
-var SimpleEventPlugin = require('SimpleEventPlugin');
+import BeforeInputEventPlugin from 'BeforeInputEventPlugin';
+import ChangeEventPlugin from 'ChangeEventPlugin';
+import DOMEventPluginOrder from 'DOMEventPluginOrder';
+import EnterLeaveEventPlugin from 'EnterLeaveEventPlugin';
+import {injection as EventPluginRegistryInjection} from 'EventPluginRegistry';
+import {injection as EventPluginUtilsInjection} from 'EventPluginUtils';
+import {handleTopLevel} from 'ReactBrowserEventEmitter';
+import * as ReactDOMComponentTree from 'ReactDOMComponentTree';
+import {setHandleTopLevel} from 'ReactDOMEventListener';
+import SelectEventPlugin from 'SelectEventPlugin';
+import SimpleEventPlugin from 'SimpleEventPlugin';
 
-ReactDOMEventListener.setHandleTopLevel(
-  ReactBrowserEventEmitter.handleTopLevel,
-);
+setHandleTopLevel(handleTopLevel);
 
 /**
  * Inject modules for resolving DOM hierarchy and plugin ordering.
  */
-EventPluginHub.injection.injectEventPluginOrder(DOMEventPluginOrder);
-EventPluginUtils.injection.injectComponentTree(ReactDOMComponentTree);
+EventPluginRegistryInjection.injectEventPluginOrder(DOMEventPluginOrder);
+EventPluginUtilsInjection.injectComponentTree(ReactDOMComponentTree);
 
 /**
  * Some important event plugins included by default (without having to require
  * them).
  */
-EventPluginHub.injection.injectEventPluginsByName({
-  SimpleEventPlugin: SimpleEventPlugin,
-  EnterLeaveEventPlugin: EnterLeaveEventPlugin,
-  ChangeEventPlugin: ChangeEventPlugin,
-  SelectEventPlugin: SelectEventPlugin,
-  BeforeInputEventPlugin: BeforeInputEventPlugin,
+EventPluginRegistryInjection.injectEventPluginsByName({
+  SimpleEventPlugin,
+  EnterLeaveEventPlugin,
+  ChangeEventPlugin,
+  SelectEventPlugin,
+  BeforeInputEventPlugin,
 });
diff --git a/src/renderers/dom/shared/ReactDOMComponentFlags.js b/src/renderers/dom/shared/ReactDOMComponentFlags.js
deleted file mode 100644
index f3da64af145..00000000000
--- a/src/renderers/dom/shared/ReactDOMComponentFlags.js
+++ /dev/null
@@ -1,18 +0,0 @@
-/**
- * Copyright 2015-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMComponentFlags
- */
-
-'use strict';
-
-var ReactDOMComponentFlags = {
-  hasCachedChildNodes: 1 << 0,
-};
-
-module.exports = ReactDOMComponentFlags;
diff --git a/src/renderers/dom/shared/ReactDOMComponentTree.js b/src/renderers/dom/shared/ReactDOMComponentTree.js
index 700ffb68118..e3884fe5772 100644
--- a/src/renderers/dom/shared/ReactDOMComponentTree.js
+++ b/src/renderers/dom/shared/ReactDOMComponentTree.js
@@ -11,121 +11,22 @@
 
 'use strict';
 
-var DOMProperty = require('DOMProperty');
-var ReactDOMComponentFlags = require('ReactDOMComponentFlags');
-var {HostComponent, HostText} = require('ReactTypeOfWork');
-var {ELEMENT_NODE, COMMENT_NODE} = require('HTMLNodeType');
-
-var invariant = require('fbjs/lib/invariant');
-
-var ATTR_NAME = DOMProperty.ID_ATTRIBUTE_NAME;
-var Flags = ReactDOMComponentFlags;
+import {HostComponent, HostText} from 'ReactTypeOfWork';
+import invariant from 'fbjs/lib/invariant';
 
 var randomKey = Math.random().toString(36).slice(2);
-
 var internalInstanceKey = '__reactInternalInstance$' + randomKey;
-
 var internalEventHandlersKey = '__reactEventHandlers$' + randomKey;
 
-/**
- * Check if a given node should be cached.
- */
-function shouldPrecacheNode(node, nodeID) {
-  return (
-    (node.nodeType === ELEMENT_NODE &&
-      node.getAttribute(ATTR_NAME) === '' + nodeID) ||
-    (node.nodeType === COMMENT_NODE &&
-      node.nodeValue === ' react-text: ' + nodeID + ' ') ||
-    (node.nodeType === COMMENT_NODE &&
-      node.nodeValue === ' react-empty: ' + nodeID + ' ')
-  );
-}
-
-/**
- * Drill down (through composites and empty components) until we get a host or
- * host text component.
- *
- * This is pretty polymorphic but unavoidable with the current structure we have
- * for `_renderedChildren`.
- */
-function getRenderedHostOrTextFromComponent(component) {
-  var rendered;
-  while ((rendered = component._renderedComponent)) {
-    component = rendered;
-  }
-  return component;
-}
-
-/**
- * Populate `_hostNode` on the rendered host/text component with the given
- * DOM node. The passed `inst` can be a composite.
- */
-function precacheNode(inst, node) {
-  var hostInst = getRenderedHostOrTextFromComponent(inst);
-  hostInst._hostNode = node;
-  node[internalInstanceKey] = hostInst;
-}
-
-function precacheFiberNode(hostInst, node) {
+export function precacheFiberNode(hostInst, node) {
   node[internalInstanceKey] = hostInst;
 }
 
-function uncacheNode(inst) {
-  var node = inst._hostNode;
-  if (node) {
-    delete node[internalInstanceKey];
-    inst._hostNode = null;
-  }
-}
-
-/**
- * Populate `_hostNode` on each child of `inst`, assuming that the children
- * match up with the DOM (element) children of `node`.
- *
- * We cache entire levels at once to avoid an n^2 problem where we access the
- * children of a node sequentially and have to walk from the start to our target
- * node every time.
- *
- * Since we update `_renderedChildren` and the actual DOM at (slightly)
- * different times, we could race here and see a newer `_renderedChildren` than
- * the DOM nodes we see. To avoid this, ReactMultiChild calls
- * `prepareToManageChildren` before we change `_renderedChildren`, at which
- * time the container's child nodes are always cached (until it unmounts).
- */
-function precacheChildNodes(inst, node) {
-  if (inst._flags & Flags.hasCachedChildNodes) {
-    return;
-  }
-  var children = inst._renderedChildren;
-  var childNode = node.firstChild;
-  outer: for (var name in children) {
-    if (!children.hasOwnProperty(name)) {
-      continue;
-    }
-    var childInst = children[name];
-    var childID = getRenderedHostOrTextFromComponent(childInst)._domID;
-    if (childID === 0) {
-      // We're currently unmounting this child in ReactMultiChild; skip it.
-      continue;
-    }
-    // We assume the child nodes are in the same order as the child instances.
-    for (; childNode !== null; childNode = childNode.nextSibling) {
-      if (shouldPrecacheNode(childNode, childID)) {
-        precacheNode(childInst, childNode);
-        continue outer;
-      }
-    }
-    // We reached the end of the DOM children without finding an ID match.
-    invariant(false, 'Unable to find element with ID %s.', childID);
-  }
-  inst._flags |= Flags.hasCachedChildNodes;
-}
-
 /**
  * Given a DOM node, return the closest ReactDOMComponent or
  * ReactDOMTextComponent instance ancestor.
  */
-function getClosestInstanceFromNode(node) {
+export function getClosestInstanceFromNode(node) {
   if (node[internalInstanceKey]) {
     return node[internalInstanceKey];
   }
@@ -151,9 +52,6 @@ function getClosestInstanceFromNode(node) {
   }
   for (; node && (inst = node[internalInstanceKey]); node = parents.pop()) {
     closest = inst;
-    if (parents.length) {
-      precacheChildNodes(inst, node);
-    }
   }
 
   return closest;
@@ -163,30 +61,23 @@ function getClosestInstanceFromNode(node) {
  * Given a DOM node, return the ReactDOMComponent or ReactDOMTextComponent
  * instance, or null if the node was not rendered by this React.
  */
-function getInstanceFromNode(node) {
+export function getInstanceFromNode(node) {
   var inst = node[internalInstanceKey];
   if (inst) {
     if (inst.tag === HostComponent || inst.tag === HostText) {
       return inst;
-    } else if (inst._hostNode === node) {
-      return inst;
     } else {
       return null;
     }
   }
-  inst = getClosestInstanceFromNode(node);
-  if (inst != null && inst._hostNode === node) {
-    return inst;
-  } else {
-    return null;
-  }
+  return null;
 }
 
 /**
  * Given a ReactDOMComponent or ReactDOMTextComponent, return the corresponding
  * DOM node.
  */
-function getNodeFromInstance(inst) {
+export function getNodeFromInstance(inst) {
   if (inst.tag === HostComponent || inst.tag === HostText) {
     // In Fiber this, is just the state node right now. We assume it will be
     // a host component or host text.
@@ -195,53 +86,13 @@ function getNodeFromInstance(inst) {
 
   // Without this first invariant, passing a non-DOM-component triggers the next
   // invariant for a missing parent, which is super confusing.
-  invariant(
-    inst._hostNode !== undefined,
-    'getNodeFromInstance: Invalid argument.',
-  );
-
-  if (inst._hostNode) {
-    return inst._hostNode;
-  }
-
-  // Walk up the tree until we find an ancestor whose DOM node we have cached.
-  var parents = [];
-  while (!inst._hostNode) {
-    parents.push(inst);
-    invariant(
-      inst._hostParent,
-      'React DOM tree root should always have a node reference.',
-    );
-    inst = inst._hostParent;
-  }
-
-  // Now parents contains each ancestor that does *not* have a cached native
-  // node, and `inst` is the deepest ancestor that does.
-  for (; parents.length; inst = parents.pop()) {
-    precacheChildNodes(inst, inst._hostNode);
-  }
-
-  return inst._hostNode;
+  invariant(false, 'getNodeFromInstance: Invalid argument.');
 }
 
-function getFiberCurrentPropsFromNode(node) {
+export function getFiberCurrentPropsFromNode(node) {
   return node[internalEventHandlersKey] || null;
 }
 
-function updateFiberProps(node, props) {
+export function updateFiberProps(node, props) {
   node[internalEventHandlersKey] = props;
 }
-
-var ReactDOMComponentTree = {
-  getClosestInstanceFromNode: getClosestInstanceFromNode,
-  getInstanceFromNode: getInstanceFromNode,
-  getNodeFromInstance: getNodeFromInstance,
-  precacheChildNodes: precacheChildNodes,
-  precacheNode: precacheNode,
-  uncacheNode: uncacheNode,
-  precacheFiberNode: precacheFiberNode,
-  getFiberCurrentPropsFromNode,
-  updateFiberProps,
-};
-
-module.exports = ReactDOMComponentTree;
diff --git a/src/renderers/dom/shared/ReactDOMEventListener.js b/src/renderers/dom/shared/ReactDOMEventListener.js
index 671588b6817..5e1011a130c 100644
--- a/src/renderers/dom/shared/ReactDOMEventListener.js
+++ b/src/renderers/dom/shared/ReactDOMEventListener.js
@@ -11,15 +11,12 @@
 
 'use strict';
 
-var EventListener = require('fbjs/lib/EventListener');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactFiberTreeReflection = require('ReactFiberTreeReflection');
-var ReactGenericBatching = require('ReactGenericBatching');
-var ReactTypeOfWork = require('ReactTypeOfWork');
-
-var getEventTarget = require('getEventTarget');
-
-var {HostRoot} = ReactTypeOfWork;
+import EventListener from 'fbjs/lib/EventListener';
+import {getClosestInstanceFromNode} from 'ReactDOMComponentTree';
+import {isFiberMounted} from 'ReactFiberTreeReflection';
+import {batchedUpdates} from 'ReactGenericBatching';
+import {HostRoot} from 'ReactTypeOfWork';
+import getEventTarget from 'getEventTarget';
 
 var CALLBACK_BOOKKEEPING_POOL_SIZE = 10;
 var callbackBookkeepingPool = [];
@@ -33,22 +30,14 @@ function findRootContainerNode(inst) {
   // TODO: It may be a good idea to cache this to prevent unnecessary DOM
   // traversal, but caching is difficult to do correctly without using a
   // mutation observer to listen for all DOM changes.
-  if (typeof inst.tag === 'number') {
-    while (inst.return) {
-      inst = inst.return;
-    }
-    if (inst.tag !== HostRoot) {
-      // This can happen if we're in a detached tree.
-      return null;
-    }
-    return inst.stateNode.containerInfo;
-  } else {
-    while (inst._hostParent) {
-      inst = inst._hostParent;
-    }
-    var rootNode = ReactDOMComponentTree.getNodeFromInstance(inst);
-    return rootNode.parentNode;
+  while (inst.return) {
+    inst = inst.return;
   }
+  if (inst.tag !== HostRoot) {
+    // This can happen if we're in a detached tree.
+    return null;
+  }
+  return inst.stateNode.containerInfo;
 }
 
 // Used to store ancestor hierarchy in top level callback
@@ -96,12 +85,12 @@ function handleTopLevelImpl(bookKeeping) {
       break;
     }
     bookKeeping.ancestors.push(ancestor);
-    ancestor = ReactDOMComponentTree.getClosestInstanceFromNode(root);
+    ancestor = getClosestInstanceFromNode(root);
   } while (ancestor);
 
   for (var i = 0; i < bookKeeping.ancestors.length; i++) {
     targetInst = bookKeeping.ancestors[i];
-    ReactDOMEventListener._handleTopLevel(
+    _handleTopLevel(
       bookKeeping.topLevelType,
       targetInst,
       bookKeeping.nativeEvent,
@@ -110,99 +99,93 @@ function handleTopLevelImpl(bookKeeping) {
   }
 }
 
-var ReactDOMEventListener = {
-  _enabled: true,
-  _handleTopLevel: null,
-
-  setHandleTopLevel: function(handleTopLevel) {
-    ReactDOMEventListener._handleTopLevel = handleTopLevel;
-  },
-
-  setEnabled: function(enabled) {
-    ReactDOMEventListener._enabled = !!enabled;
-  },
-
-  isEnabled: function() {
-    return ReactDOMEventListener._enabled;
-  },
-
-  /**
-   * Traps top-level events by using event bubbling.
-   *
-   * @param {string} topLevelType Record from `BrowserEventConstants`.
-   * @param {string} handlerBaseName Event name (e.g. "click").
-   * @param {object} element Element on which to attach listener.
-   * @return {?object} An object with a remove function which will forcefully
-   *                  remove the listener.
-   * @internal
-   */
-  trapBubbledEvent: function(topLevelType, handlerBaseName, element) {
-    if (!element) {
-      return null;
-    }
-    return EventListener.listen(
-      element,
-      handlerBaseName,
-      ReactDOMEventListener.dispatchEvent.bind(null, topLevelType),
-    );
-  },
-
-  /**
-   * Traps a top-level event by using event capturing.
-   *
-   * @param {string} topLevelType Record from `BrowserEventConstants`.
-   * @param {string} handlerBaseName Event name (e.g. "click").
-   * @param {object} element Element on which to attach listener.
-   * @return {?object} An object with a remove function which will forcefully
-   *                  remove the listener.
-   * @internal
-   */
-  trapCapturedEvent: function(topLevelType, handlerBaseName, element) {
-    if (!element) {
-      return null;
-    }
-    return EventListener.capture(
-      element,
-      handlerBaseName,
-      ReactDOMEventListener.dispatchEvent.bind(null, topLevelType),
-    );
-  },
+let _enabled = true;
+let _handleTopLevel = null;
 
-  dispatchEvent: function(topLevelType, nativeEvent) {
-    if (!ReactDOMEventListener._enabled) {
-      return;
-    }
+export function setHandleTopLevel(handleTopLevel) {
+  _handleTopLevel = handleTopLevel;
+}
 
-    var nativeEventTarget = getEventTarget(nativeEvent);
-    var targetInst = ReactDOMComponentTree.getClosestInstanceFromNode(
-      nativeEventTarget,
-    );
-    if (
-      targetInst !== null &&
-      typeof targetInst.tag === 'number' &&
-      !ReactFiberTreeReflection.isFiberMounted(targetInst)
-    ) {
-      // If we get an event (ex: img onload) before committing that
-      // component's mount, ignore it for now (that is, treat it as if it was an
-      // event on a non-React tree). We might also consider queueing events and
-      // dispatching them after the mount.
-      targetInst = null;
-    }
+export function setEnabled(enabled) {
+  _enabled = !!enabled;
+}
 
-    var bookKeeping = getTopLevelCallbackBookKeeping(
-      topLevelType,
-      nativeEvent,
-      targetInst,
-    );
+export function isEnabled() {
+  return _enabled;
+}
 
-    try {
-      // Event queue being processed in the same cycle allows
-      // `preventDefault`.
-      ReactGenericBatching.batchedUpdates(handleTopLevelImpl, bookKeeping);
-    } finally {
-      releaseTopLevelCallbackBookKeeping(bookKeeping);
-    }
-  },
-};
+/**
+ * Traps top-level events by using event bubbling.
+ *
+ * @param {string} topLevelType Record from `BrowserEventConstants`.
+ * @param {string} handlerBaseName Event name (e.g. "click").
+ * @param {object} element Element on which to attach listener.
+ * @return {?object} An object with a remove function which will forcefully
+ *                  remove the listener.
+ * @internal
+ */
+export function trapBubbledEvent(topLevelType, handlerBaseName, element) {
+  if (!element) {
+    return null;
+  }
+  return EventListener.listen(
+    element,
+    handlerBaseName,
+    dispatchEvent.bind(null, topLevelType),
+  );
+}
+
+/**
+ * Traps a top-level event by using event capturing.
+ *
+ * @param {string} topLevelType Record from `BrowserEventConstants`.
+ * @param {string} handlerBaseName Event name (e.g. "click").
+ * @param {object} element Element on which to attach listener.
+ * @return {?object} An object with a remove function which will forcefully
+ *                  remove the listener.
+ * @internal
+ */
+export function trapCapturedEvent(topLevelType, handlerBaseName, element) {
+  if (!element) {
+    return null;
+  }
+  return EventListener.capture(
+    element,
+    handlerBaseName,
+    dispatchEvent.bind(null, topLevelType),
+  );
+}
 
-module.exports = ReactDOMEventListener;
+export function dispatchEvent(topLevelType, nativeEvent) {
+  if (!_enabled) {
+    return;
+  }
+
+  var nativeEventTarget = getEventTarget(nativeEvent);
+  var targetInst = getClosestInstanceFromNode(nativeEventTarget);
+  if (
+    targetInst !== null &&
+    typeof targetInst.tag === 'number' &&
+    !isFiberMounted(targetInst)
+  ) {
+    // If we get an event (ex: img onload) before committing that
+    // component's mount, ignore it for now (that is, treat it as if it was an
+    // event on a non-React tree). We might also consider queueing events and
+    // dispatching them after the mount.
+    targetInst = null;
+  }
+
+  var bookKeeping = getTopLevelCallbackBookKeeping(
+    topLevelType,
+    nativeEvent,
+    targetInst,
+  );
+
+  try {
+    // Event queue being processed in the same cycle allows
+    // `preventDefault`.
+    batchedUpdates(handleTopLevelImpl, bookKeeping);
+  } finally {
+    releaseTopLevelCallbackBookKeeping(bookKeeping);
+  }
+}
diff --git a/src/renderers/dom/shared/ReactDOMFeatureFlags.js b/src/renderers/dom/shared/ReactDOMFeatureFlags.js
index bb24b4a12fd..ef69915134c 100644
--- a/src/renderers/dom/shared/ReactDOMFeatureFlags.js
+++ b/src/renderers/dom/shared/ReactDOMFeatureFlags.js
@@ -13,7 +13,6 @@
 
 var ReactDOMFeatureFlags = {
   fiberAsyncScheduling: false,
-  useFiber: true,
 };
 
-module.exports = ReactDOMFeatureFlags;
+export default ReactDOMFeatureFlags;
diff --git a/src/renderers/dom/shared/ReactDOMInjection.js b/src/renderers/dom/shared/ReactDOMInjection.js
index a14c7cc2d62..7fd6efd8331 100644
--- a/src/renderers/dom/shared/ReactDOMInjection.js
+++ b/src/renderers/dom/shared/ReactDOMInjection.js
@@ -11,9 +11,9 @@
 
 'use strict';
 
-var DOMProperty = require('DOMProperty');
-var HTMLDOMPropertyConfig = require('HTMLDOMPropertyConfig');
-var SVGDOMPropertyConfig = require('SVGDOMPropertyConfig');
+import {injection as DOMPropertyInjection} from 'DOMProperty';
+import HTMLDOMPropertyConfig from 'HTMLDOMPropertyConfig';
+import SVGDOMPropertyConfig from 'SVGDOMPropertyConfig';
 
-DOMProperty.injection.injectDOMPropertyConfig(HTMLDOMPropertyConfig);
-DOMProperty.injection.injectDOMPropertyConfig(SVGDOMPropertyConfig);
+DOMPropertyInjection.injectDOMPropertyConfig(HTMLDOMPropertyConfig);
+DOMPropertyInjection.injectDOMPropertyConfig(SVGDOMPropertyConfig);
diff --git a/src/renderers/dom/shared/ReactDOMSelection.js b/src/renderers/dom/shared/ReactDOMSelection.js
index 4aaa9e86dd8..ab94e18ed73 100644
--- a/src/renderers/dom/shared/ReactDOMSelection.js
+++ b/src/renderers/dom/shared/ReactDOMSelection.js
@@ -11,8 +11,8 @@
 
 'use strict';
 
-var getNodeForCharacterOffset = require('getNodeForCharacterOffset');
-var getTextContentAccessor = require('getTextContentAccessor');
+import getNodeForCharacterOffset from 'getNodeForCharacterOffset';
+import getTextContentAccessor from 'getTextContentAccessor';
 
 /**
  * While `isCollapsed` is available on the Selection object and `collapsed`
@@ -27,7 +27,7 @@ function isCollapsed(anchorNode, anchorOffset, focusNode, focusOffset) {
  * @param {DOMElement} node
  * @return {?object}
  */
-function getModernOffsets(node) {
+export function getOffsets(node) {
   var selection = window.getSelection && window.getSelection();
 
   if (!selection || selection.rangeCount === 0) {
@@ -107,7 +107,7 @@ function getModernOffsets(node) {
  * @param {DOMElement|DOMTextNode} node
  * @param {object} offsets
  */
-function setModernOffsets(node, offsets) {
+export function setOffsets(node, offsets) {
   if (!window.getSelection) {
     return;
   }
@@ -142,18 +142,3 @@ function setModernOffsets(node, offsets) {
     }
   }
 }
-
-var ReactDOMSelection = {
-  /**
-   * @param {DOMElement} node
-   */
-  getOffsets: getModernOffsets,
-
-  /**
-   * @param {DOMElement|DOMTextNode} node
-   * @param {object} offsets
-   */
-  setOffsets: setModernOffsets,
-};
-
-module.exports = ReactDOMSelection;
diff --git a/src/renderers/dom/shared/ReactDOMUnstableNativeDependenciesEntry.js b/src/renderers/dom/shared/ReactDOMUnstableNativeDependenciesEntry.js
index a716d81d300..2c8605af499 100644
--- a/src/renderers/dom/shared/ReactDOMUnstableNativeDependenciesEntry.js
+++ b/src/renderers/dom/shared/ReactDOMUnstableNativeDependenciesEntry.js
@@ -9,12 +9,12 @@
  * @providesModule ReactDOMUnstableNativeDependenciesEntry
  */
 
-const EventPluginUtils = require('EventPluginUtils');
-const ResponderEventPlugin = require('ResponderEventPlugin');
-const ResponderTouchHistoryStore = require('ResponderTouchHistoryStore');
+import {injection as EventPluginUtilsInjection} from 'EventPluginUtils';
+import ResponderEventPlugin from 'ResponderEventPlugin';
+import ResponderTouchHistoryStore from 'ResponderTouchHistoryStore';
 
 const ReactDOMUnstableNativeDependencies = {
-  injectComponentTree: EventPluginUtils.injection.injectComponentTree,
+  injectComponentTree: EventPluginUtilsInjection.injectComponentTree,
   ResponderEventPlugin,
   ResponderTouchHistoryStore,
 };
@@ -24,6 +24,8 @@ const ReactDOM = require('react-dom');
 const {
   ReactDOMComponentTree,
 } = ReactDOM.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED;
-ReactDOMUnstableNativeDependencies.injectComponentTree(ReactDOMComponentTree);
+EventPluginUtilsInjection.injectComponentTree(ReactDOMComponentTree);
 
-module.exports = ReactDOMUnstableNativeDependencies;
+// TODO: this fixes Rollup build but probably breaks Jest.
+// Need to figure something out.
+export default ReactDOMUnstableNativeDependencies;
diff --git a/src/renderers/dom/shared/ReactInputSelection.js b/src/renderers/dom/shared/ReactInputSelection.js
index 427e71f88a7..f4cefe5f54d 100644
--- a/src/renderers/dom/shared/ReactInputSelection.js
+++ b/src/renderers/dom/shared/ReactInputSelection.js
@@ -11,12 +11,12 @@
 
 'use strict';
 
-var ReactDOMSelection = require('ReactDOMSelection');
-var {ELEMENT_NODE} = require('HTMLNodeType');
+import {getOffsets, setOffsets} from 'ReactDOMSelection';
+import {ELEMENT_NODE} from 'HTMLNodeType';
 
-var containsNode = require('fbjs/lib/containsNode');
-var focusNode = require('fbjs/lib/focusNode');
-var getActiveElement = require('fbjs/lib/getActiveElement');
+import containsNode from 'fbjs/lib/containsNode';
+import focusNode from 'fbjs/lib/focusNode';
+import getActiveElement from 'fbjs/lib/getActiveElement';
 
 function isInDocument(node) {
   return containsNode(document.documentElement, node);
@@ -28,107 +28,104 @@ function isInDocument(node) {
  * assume buttons have range selections allowed).
  * Input selection module for React.
  */
-var ReactInputSelection = {
-  hasSelectionCapabilities: function(elem) {
-    var nodeName = elem && elem.nodeName && elem.nodeName.toLowerCase();
-    return (
-      nodeName &&
-      ((nodeName === 'input' && elem.type === 'text') ||
-        nodeName === 'textarea' ||
-        elem.contentEditable === 'true')
-    );
-  },
-
-  getSelectionInformation: function() {
-    var focusedElem = getActiveElement();
-    return {
-      focusedElem: focusedElem,
-      selectionRange: ReactInputSelection.hasSelectionCapabilities(focusedElem)
-        ? ReactInputSelection.getSelection(focusedElem)
-        : null,
-    };
-  },
-
-  /**
-   * @restoreSelection: If any selection information was potentially lost,
-   * restore it. This is useful when performing operations that could remove dom
-   * nodes and place them back in, resulting in focus being lost.
-   */
-  restoreSelection: function(priorSelectionInformation) {
-    var curFocusedElem = getActiveElement();
-    var priorFocusedElem = priorSelectionInformation.focusedElem;
-    var priorSelectionRange = priorSelectionInformation.selectionRange;
-    if (curFocusedElem !== priorFocusedElem && isInDocument(priorFocusedElem)) {
-      if (ReactInputSelection.hasSelectionCapabilities(priorFocusedElem)) {
-        ReactInputSelection.setSelection(priorFocusedElem, priorSelectionRange);
-      }
 
-      // Focusing a node can change the scroll position, which is undesirable
-      const ancestors = [];
-      let ancestor = priorFocusedElem;
-      while ((ancestor = ancestor.parentNode)) {
-        if (ancestor.nodeType === ELEMENT_NODE) {
-          ancestors.push({
-            element: ancestor,
-            left: ancestor.scrollLeft,
-            top: ancestor.scrollTop,
-          });
-        }
-      }
+export function hasSelectionCapabilities(elem) {
+  var nodeName = elem && elem.nodeName && elem.nodeName.toLowerCase();
+  return (
+    nodeName &&
+    ((nodeName === 'input' && elem.type === 'text') ||
+      nodeName === 'textarea' ||
+      elem.contentEditable === 'true')
+  );
+}
 
-      focusNode(priorFocusedElem);
+export function getSelectionInformation() {
+  var focusedElem = getActiveElement();
+  return {
+    focusedElem: focusedElem,
+    selectionRange: hasSelectionCapabilities(focusedElem)
+      ? getSelection(focusedElem)
+      : null,
+  };
+}
 
-      for (let i = 0; i < ancestors.length; i++) {
-        const info = ancestors[i];
-        info.element.scrollLeft = info.left;
-        info.element.scrollTop = info.top;
-      }
-    }
-  },
-
-  /**
-   * @getSelection: Gets the selection bounds of a focused textarea, input or
-   * contentEditable node.
-   * -@input: Look up selection bounds of this input
-   * -@return {start: selectionStart, end: selectionEnd}
-   */
-  getSelection: function(input) {
-    var selection;
-
-    if ('selectionStart' in input) {
-      // Modern browser with input or textarea.
-      selection = {
-        start: input.selectionStart,
-        end: input.selectionEnd,
-      };
-    } else {
-      // Content editable or old IE textarea.
-      selection = ReactDOMSelection.getOffsets(input);
+/**
+ * @restoreSelection: If any selection information was potentially lost,
+ * restore it. This is useful when performing operations that could remove dom
+ * nodes and place them back in, resulting in focus being lost.
+ */
+export function restoreSelection(priorSelectionInformation) {
+  var curFocusedElem = getActiveElement();
+  var priorFocusedElem = priorSelectionInformation.focusedElem;
+  var priorSelectionRange = priorSelectionInformation.selectionRange;
+  if (curFocusedElem !== priorFocusedElem && isInDocument(priorFocusedElem)) {
+    if (hasSelectionCapabilities(priorFocusedElem)) {
+      setSelection(priorFocusedElem, priorSelectionRange);
     }
 
-    return selection || {start: 0, end: 0};
-  },
-
-  /**
-   * @setSelection: Sets the selection bounds of a textarea or input and focuses
-   * the input.
-   * -@input     Set selection bounds of this input or textarea
-   * -@offsets   Object of same form that is returned from get*
-   */
-  setSelection: function(input, offsets) {
-    var start = offsets.start;
-    var end = offsets.end;
-    if (end === undefined) {
-      end = start;
+    // Focusing a node can change the scroll position, which is undesirable
+    const ancestors = [];
+    let ancestor = priorFocusedElem;
+    while ((ancestor = ancestor.parentNode)) {
+      if (ancestor.nodeType === ELEMENT_NODE) {
+        ancestors.push({
+          element: ancestor,
+          left: ancestor.scrollLeft,
+          top: ancestor.scrollTop,
+        });
+      }
     }
 
-    if ('selectionStart' in input) {
-      input.selectionStart = start;
-      input.selectionEnd = Math.min(end, input.value.length);
-    } else {
-      ReactDOMSelection.setOffsets(input, offsets);
+    focusNode(priorFocusedElem);
+
+    for (let i = 0; i < ancestors.length; i++) {
+      const info = ancestors[i];
+      info.element.scrollLeft = info.left;
+      info.element.scrollTop = info.top;
     }
-  },
-};
+  }
+}
+
+/**
+ * @getSelection: Gets the selection bounds of a focused textarea, input or
+ * contentEditable node.
+ * -@input: Look up selection bounds of this input
+ * -@return {start: selectionStart, end: selectionEnd}
+ */
+export function getSelection(input) {
+  var selection;
+
+  if ('selectionStart' in input) {
+    // Modern browser with input or textarea.
+    selection = {
+      start: input.selectionStart,
+      end: input.selectionEnd,
+    };
+  } else {
+    // Content editable or old IE textarea.
+    selection = getOffsets(input);
+  }
 
-module.exports = ReactInputSelection;
+  return selection || {start: 0, end: 0};
+}
+
+/**
+ * @setSelection: Sets the selection bounds of a textarea or input and focuses
+ * the input.
+ * -@input     Set selection bounds of this input or textarea
+ * -@offsets   Object of same form that is returned from get*
+ */
+export function setSelection(input, offsets) {
+  var start = offsets.start;
+  var end = offsets.end;
+  if (end === undefined) {
+    end = start;
+  }
+
+  if ('selectionStart' in input) {
+    input.selectionStart = start;
+    input.selectionEnd = Math.min(end, input.value.length);
+  } else {
+    setOffsets(input, offsets);
+  }
+}
diff --git a/src/renderers/dom/shared/SVGDOMPropertyConfig.js b/src/renderers/dom/shared/SVGDOMPropertyConfig.js
index 46db12aa425..fb865af570b 100644
--- a/src/renderers/dom/shared/SVGDOMPropertyConfig.js
+++ b/src/renderers/dom/shared/SVGDOMPropertyConfig.js
@@ -147,4 +147,4 @@ ATTRS.forEach(original => {
   SVGDOMPropertyConfig.DOMAttributeNames[reactName] = original;
 });
 
-module.exports = SVGDOMPropertyConfig;
+export default SVGDOMPropertyConfig;
diff --git a/src/renderers/dom/shared/__tests__/ReactBrowserEventEmitter-test.js b/src/renderers/dom/shared/__tests__/ReactBrowserEventEmitter-test.js
index 6239a6ac112..e921cfcadf2 100644
--- a/src/renderers/dom/shared/__tests__/ReactBrowserEventEmitter-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactBrowserEventEmitter-test.js
@@ -135,7 +135,7 @@ describe('ReactBrowserEventEmitter', () => {
 
     idCallOrder = [];
     tapMoveThreshold = TapEventPlugin.tapMoveThreshold;
-    EventPluginHub.injection.injectEventPluginsByName({
+    EventPluginRegistry.injection.injectEventPluginsByName({
       TapEventPlugin: TapEventPlugin,
     });
   });
diff --git a/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js b/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js
index 981c9d3ed2b..ad1823c6110 100644
--- a/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js
@@ -17,7 +17,6 @@ describe('ReactDOMComponent', () => {
   var ReactDOM;
   var ReactDOMServer;
   var inputValueTracking;
-  var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 
   function normalizeCodeLocInfo(str) {
     return str && str.replace(/\(at .+?:\d+\)/g, '(at **)');
@@ -27,7 +26,6 @@ describe('ReactDOMComponent', () => {
     jest.resetModules();
     React = require('react');
     ReactDOM = require('react-dom');
-    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
     ReactDOMServer = require('react-dom/server');
     ReactTestUtils = require('react-dom/test-utils');
     // TODO: can we express this test with only public API?
@@ -861,9 +859,7 @@ describe('ReactDOMComponent', () => {
         '<hasOwnProperty /> is using uppercase HTML',
       );
       expectDev(console.error.calls.argsFor(3)[0]).toContain(
-        ReactDOMFeatureFlags.useFiber
-          ? 'The tag <hasOwnProperty> is unrecognized in this browser'
-          : 'The tag <hasownproperty> is unrecognized in this browser',
+        'The tag <hasOwnProperty> is unrecognized in this browser',
       );
     });
 
@@ -1244,36 +1240,6 @@ describe('ReactDOMComponent', () => {
   });
 
   describe('unmountComponent', () => {
-    // Fiber does not have a clean-up phase for host components; relies on GC
-    if (!ReactDOMFeatureFlags.useFiber) {
-      it('should clean up input value tracking', () => {
-        var container = document.createElement('div');
-        var node = ReactDOM.render(
-          <input type="text" defaultValue="foo" />,
-          container,
-        );
-        var tracker = inputValueTracking._getTrackerFromNode(node);
-
-        spyOn(tracker, 'stopTracking');
-
-        ReactDOM.unmountComponentAtNode(container);
-
-        expect(tracker.stopTracking.calls.count()).toBe(1);
-      });
-
-      it('should clean up input textarea tracking', () => {
-        var container = document.createElement('div');
-        var node = ReactDOM.render(<textarea defaultValue="foo" />, container);
-        var tracker = inputValueTracking._getTrackerFromNode(node);
-
-        spyOn(tracker, 'stopTracking');
-
-        ReactDOM.unmountComponentAtNode(container);
-
-        expect(tracker.stopTracking.calls.count()).toBe(1);
-      });
-    }
-
     it('unmounts children before unsetting DOM node info', () => {
       class Inner extends React.Component {
         render() {
@@ -1323,15 +1289,12 @@ describe('ReactDOMComponent', () => {
       spyOn(console, 'error');
       ReactTestUtils.renderIntoDocument(<div><tr /><tr /></div>);
 
-      var addendum = ReactDOMFeatureFlags.useFiber
-        ? '\n    in tr (at **)' + '\n    in div (at **)'
-        : ' See div > tr.';
-
       expectDev(console.error.calls.count()).toBe(1);
       expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
         'Warning: validateDOMNesting(...): <tr> cannot appear as a child of ' +
           '<div>.' +
-          addendum,
+          '\n    in tr (at **)' +
+          '\n    in div (at **)',
       );
     });
 
@@ -1340,16 +1303,13 @@ describe('ReactDOMComponent', () => {
       var p = document.createElement('p');
       ReactDOM.render(<span><p /></span>, p);
 
-      var addendum = ReactDOMFeatureFlags.useFiber
-        ? // There is no outer `p` here because root container is not part of the stack.
-          '\n    in p (at **)' + '\n    in span (at **)'
-        : ' See p > ... > p.';
-
       expectDev(console.error.calls.count()).toBe(1);
       expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
         'Warning: validateDOMNesting(...): <p> cannot appear as a descendant ' +
           'of <p>.' +
-          addendum,
+          // There is no outer `p` here because root container is not part of the stack.
+          '\n    in p (at **)' +
+          '\n    in span (at **)',
       );
     });
 
@@ -1371,39 +1331,31 @@ describe('ReactDOMComponent', () => {
       ReactTestUtils.renderIntoDocument(<Foo />);
       expectDev(console.error.calls.count()).toBe(3);
 
-      var addendum1 = ReactDOMFeatureFlags.useFiber
-        ? '\n    in tr (at **)' +
-            '\n    in Row (at **)' +
-            '\n    in table (at **)' +
-            '\n    in Foo (at **)'
-        : ' See Foo > table > Row > tr.';
       expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
         'Warning: validateDOMNesting(...): <tr> cannot appear as a child of ' +
           '<table>. Add a <tbody> to your code to match the DOM tree generated ' +
           'by the browser.' +
-          addendum1,
+          '\n    in tr (at **)' +
+          '\n    in Row (at **)' +
+          '\n    in table (at **)' +
+          '\n    in Foo (at **)',
       );
 
-      var addendum2 = ReactDOMFeatureFlags.useFiber
-        ? '\n    in tr (at **)' +
-            '\n    in Row (at **)' +
-            '\n    in table (at **)' +
-            '\n    in Foo (at **)'
-        : ' See Row > tr > #text.';
       expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(1)[0])).toBe(
         'Warning: validateDOMNesting(...): Text nodes cannot appear as a ' +
           'child of <tr>.' +
-          addendum2,
+          '\n    in tr (at **)' +
+          '\n    in Row (at **)' +
+          '\n    in table (at **)' +
+          '\n    in Foo (at **)',
       );
 
-      var addendum3 = ReactDOMFeatureFlags.useFiber
-        ? '\n    in table (at **)' + '\n    in Foo (at **)'
-        : ' See Foo > table > #text.';
       expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(2)[0])).toBe(
         'Warning: validateDOMNesting(...): Whitespace text nodes cannot ' +
           "appear as a child of <table>. Make sure you don't have any extra " +
           'whitespace between tags on each line of your source code.' +
-          addendum3,
+          '\n    in table (at **)' +
+          '\n    in Foo (at **)',
       );
     });
 
@@ -1439,13 +1391,11 @@ describe('ReactDOMComponent', () => {
       expectDev(
         normalizeCodeLocInfo(console.error.calls.argsFor(0)[0]),
       ).toContain(
-        ReactDOMFeatureFlags.useFiber
-          ? '\n    in tr (at **)' +
-              '\n    in Row (at **)' +
-              '\n    in FancyRow (at **)' +
-              '\n    in table (at **)' +
-              '\n    in Viz1 (at **)'
-          : 'See Viz1 > table > FancyRow > Row > tr.',
+        '\n    in tr (at **)' +
+          '\n    in Row (at **)' +
+          '\n    in FancyRow (at **)' +
+          '\n    in table (at **)' +
+          '\n    in Viz1 (at **)',
       );
 
       function Viz2() {
@@ -1459,15 +1409,13 @@ describe('ReactDOMComponent', () => {
       expectDev(
         normalizeCodeLocInfo(console.error.calls.argsFor(1)[0]),
       ).toContain(
-        ReactDOMFeatureFlags.useFiber
-          ? '\n    in tr (at **)' +
-              '\n    in Row (at **)' +
-              '\n    in FancyRow (at **)' +
-              '\n    in table (at **)' +
-              '\n    in Table (at **)' +
-              '\n    in FancyTable (at **)' +
-              '\n    in Viz2 (at **)'
-          : 'See Viz2 > FancyTable > Table > table > FancyRow > Row > tr.',
+        '\n    in tr (at **)' +
+          '\n    in Row (at **)' +
+          '\n    in FancyRow (at **)' +
+          '\n    in table (at **)' +
+          '\n    in Table (at **)' +
+          '\n    in FancyTable (at **)' +
+          '\n    in Viz2 (at **)',
       );
 
       ReactTestUtils.renderIntoDocument(<FancyTable><FancyRow /></FancyTable>);
@@ -1475,14 +1423,12 @@ describe('ReactDOMComponent', () => {
       expectDev(
         normalizeCodeLocInfo(console.error.calls.argsFor(2)[0]),
       ).toContain(
-        ReactDOMFeatureFlags.useFiber
-          ? '\n    in tr (at **)' +
-              '\n    in Row (at **)' +
-              '\n    in FancyRow (at **)' +
-              '\n    in table (at **)' +
-              '\n    in Table (at **)' +
-              '\n    in FancyTable (at **)'
-          : 'See FancyTable > Table > table > FancyRow > Row > tr.',
+        '\n    in tr (at **)' +
+          '\n    in Row (at **)' +
+          '\n    in FancyRow (at **)' +
+          '\n    in table (at **)' +
+          '\n    in Table (at **)' +
+          '\n    in FancyTable (at **)',
       );
 
       ReactTestUtils.renderIntoDocument(<table><FancyRow /></table>);
@@ -1490,12 +1436,10 @@ describe('ReactDOMComponent', () => {
       expectDev(
         normalizeCodeLocInfo(console.error.calls.argsFor(3)[0]),
       ).toContain(
-        ReactDOMFeatureFlags.useFiber
-          ? '\n    in tr (at **)' +
-              '\n    in Row (at **)' +
-              '\n    in FancyRow (at **)' +
-              '\n    in table (at **)'
-          : 'See table > FancyRow > Row > tr.',
+        '\n    in tr (at **)' +
+          '\n    in Row (at **)' +
+          '\n    in FancyRow (at **)' +
+          '\n    in table (at **)',
       );
 
       ReactTestUtils.renderIntoDocument(<FancyTable><tr /></FancyTable>);
@@ -1503,12 +1447,10 @@ describe('ReactDOMComponent', () => {
       expectDev(
         normalizeCodeLocInfo(console.error.calls.argsFor(4)[0]),
       ).toContain(
-        ReactDOMFeatureFlags.useFiber
-          ? '\n    in tr (at **)' +
-              '\n    in table (at **)' +
-              '\n    in Table (at **)' +
-              '\n    in FancyTable (at **)'
-          : 'See FancyTable > Table > table > tr.',
+        '\n    in tr (at **)' +
+          '\n    in table (at **)' +
+          '\n    in Table (at **)' +
+          '\n    in FancyTable (at **)',
       );
 
       class Link extends React.Component {
@@ -1522,13 +1464,11 @@ describe('ReactDOMComponent', () => {
       expectDev(
         normalizeCodeLocInfo(console.error.calls.argsFor(5)[0]),
       ).toContain(
-        ReactDOMFeatureFlags.useFiber
-          ? '\n    in a (at **)' +
-              '\n    in Link (at **)' +
-              '\n    in div (at **)' +
-              '\n    in a (at **)' +
-              '\n    in Link (at **)'
-          : 'See Link > a > ... > Link > a.',
+        '\n    in a (at **)' +
+          '\n    in Link (at **)' +
+          '\n    in div (at **)' +
+          '\n    in a (at **)' +
+          '\n    in Link (at **)',
       );
     });
 
diff --git a/src/renderers/dom/shared/__tests__/ReactDOMComponentTree-test.js b/src/renderers/dom/shared/__tests__/ReactDOMComponentTree-test.js
index fd1b463d5f0..2873d0b2f70 100644
--- a/src/renderers/dom/shared/__tests__/ReactDOMComponentTree-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactDOMComponentTree-test.js
@@ -11,8 +11,6 @@
 
 'use strict';
 
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-
 describe('ReactDOMComponentTree', () => {
   var React;
   var ReactDOM;
@@ -23,25 +21,15 @@ describe('ReactDOMComponentTree', () => {
     var container = document.createElement('div');
     // Force server-rendering path:
     container.innerHTML = ReactDOMServer.renderToString(elt);
-    if (ReactDOMFeatureFlags.useFiber) {
-      return ReactDOM.hydrate(elt, container);
-    } else {
-      return ReactDOM.render(elt, container);
-    }
+    return ReactDOM.hydrate(elt, container);
   }
 
   function getTypeOf(instance) {
-    if (typeof instance.tag === 'number') {
-      return instance.type;
-    }
-    return instance._currentElement.type;
+    return instance.type;
   }
 
   function getTextOf(instance) {
-    if (typeof instance.tag === 'number') {
-      return instance.memoizedProps;
-    }
-    return instance._stringText;
+    return instance.memoizedProps;
   }
 
   beforeEach(() => {
diff --git a/src/renderers/dom/shared/__tests__/ReactDOMServerIntegration-test.js b/src/renderers/dom/shared/__tests__/ReactDOMServerIntegration-test.js
index 2f5cd7034c2..c6a936091df 100644
--- a/src/renderers/dom/shared/__tests__/ReactDOMServerIntegration-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactDOMServerIntegration-test.js
@@ -11,8 +11,6 @@
 
 'use strict';
 
-let ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-
 let ExecutionEnvironment;
 let PropTypes;
 let React;
@@ -23,7 +21,6 @@ let ReactTestUtils;
 const stream = require('stream');
 
 const TEXT_NODE_TYPE = 3;
-const COMMENT_NODE_TYPE = 8;
 
 // Helper functions for rendering tests
 // ====================================
@@ -31,7 +28,7 @@ const COMMENT_NODE_TYPE = 8;
 // promisified version of ReactDOM.render()
 function asyncReactDOMRender(reactElement, domElement, forceHydrate) {
   return new Promise(resolve => {
-    if (forceHydrate && ReactDOMFeatureFlags.useFiber) {
+    if (forceHydrate) {
       ReactDOM.hydrate(reactElement, domElement);
     } else {
       ReactDOM.render(reactElement, domElement);
@@ -215,9 +212,7 @@ const clientRenderOnBadMarkup = async (element, errorCount = 0) => {
 // as that will not work in the server string scenario.
 function itRenders(desc, testFn) {
   it(`renders ${desc} with server string render`, () => testFn(serverRender));
-  if (ReactDOMFeatureFlags.useFiber) {
-    it(`renders ${desc} with server stream render`, () => testFn(streamRender));
-  }
+  it(`renders ${desc} with server stream render`, () => testFn(streamRender));
   itClientRenders(desc, testFn);
 }
 
@@ -327,7 +322,6 @@ function resetModules() {
   PropTypes = require('prop-types');
   React = require('react');
   ReactDOM = require('react-dom');
-  ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
   ReactTestUtils = require('react-dom/test-utils');
 
   // Now we reset the modules again to load the server renderer.
@@ -362,97 +356,95 @@ describe('ReactDOMServerIntegration', () => {
       expect(e.firstChild.tagName).toBe('BR');
     });
 
-    if (ReactDOMFeatureFlags.useFiber) {
-      itRenders('a string', async render => {
-        let e = await render('Hello');
-        expect(e.nodeType).toBe(3);
-        expect(e.nodeValue).toMatch('Hello');
-      });
+    itRenders('a string', async render => {
+      let e = await render('Hello');
+      expect(e.nodeType).toBe(3);
+      expect(e.nodeValue).toMatch('Hello');
+    });
 
-      itRenders('a number', async render => {
-        let e = await render(42);
-        expect(e.nodeType).toBe(3);
-        expect(e.nodeValue).toMatch('42');
-      });
+    itRenders('a number', async render => {
+      let e = await render(42);
+      expect(e.nodeType).toBe(3);
+      expect(e.nodeValue).toMatch('42');
+    });
 
-      itRenders('an array with one child', async render => {
-        let e = await render([<div key={1}>text1</div>]);
-        let parent = e.parentNode;
-        expect(parent.childNodes[0].tagName).toBe('DIV');
-      });
+    itRenders('an array with one child', async render => {
+      let e = await render([<div key={1}>text1</div>]);
+      let parent = e.parentNode;
+      expect(parent.childNodes[0].tagName).toBe('DIV');
+    });
 
-      itRenders('an array with several children', async render => {
-        let Header = props => {
-          return <p>header</p>;
-        };
-        let Footer = props => {
-          return [<h2 key={1}>footer</h2>, <h3 key={2}>about</h3>];
-        };
-        let e = await render([
-          <div key={1}>text1</div>,
-          <span key={2}>text2</span>,
-          <Header key={3} />,
-          <Footer key={4} />,
-        ]);
-        let parent = e.parentNode;
-        expect(parent.childNodes[0].tagName).toBe('DIV');
-        expect(parent.childNodes[1].tagName).toBe('SPAN');
-        expect(parent.childNodes[2].tagName).toBe('P');
-        expect(parent.childNodes[3].tagName).toBe('H2');
-        expect(parent.childNodes[4].tagName).toBe('H3');
-      });
-
-      itRenders('a nested array', async render => {
-        let e = await render([
-          [<div key={1}>text1</div>],
-          <span key={1}>text2</span>,
-          [[[null, <p key={1} />], false]],
-        ]);
-        let parent = e.parentNode;
-        expect(parent.childNodes[0].tagName).toBe('DIV');
-        expect(parent.childNodes[1].tagName).toBe('SPAN');
-        expect(parent.childNodes[2].tagName).toBe('P');
-      });
-
-      itRenders('an iterable', async render => {
-        const threeDivIterable = {
-          '@@iterator': function() {
-            var i = 0;
-            return {
-              next: function() {
-                if (i++ < 3) {
-                  return {value: <div key={i} />, done: false};
-                } else {
-                  return {value: undefined, done: true};
-                }
-              },
-            };
-          },
-        };
-        let e = await render(threeDivIterable);
-        let parent = e.parentNode;
-        expect(parent.childNodes.length).toBe(3);
-        expect(parent.childNodes[0].tagName).toBe('DIV');
-        expect(parent.childNodes[1].tagName).toBe('DIV');
-        expect(parent.childNodes[2].tagName).toBe('DIV');
-      });
+    itRenders('an array with several children', async render => {
+      let Header = props => {
+        return <p>header</p>;
+      };
+      let Footer = props => {
+        return [<h2 key={1}>footer</h2>, <h3 key={2}>about</h3>];
+      };
+      let e = await render([
+        <div key={1}>text1</div>,
+        <span key={2}>text2</span>,
+        <Header key={3} />,
+        <Footer key={4} />,
+      ]);
+      let parent = e.parentNode;
+      expect(parent.childNodes[0].tagName).toBe('DIV');
+      expect(parent.childNodes[1].tagName).toBe('SPAN');
+      expect(parent.childNodes[2].tagName).toBe('P');
+      expect(parent.childNodes[3].tagName).toBe('H2');
+      expect(parent.childNodes[4].tagName).toBe('H3');
+    });
 
-      itRenders('emptyish values', async render => {
-        let e = await render(0);
-        expect(e.nodeType).toBe(TEXT_NODE_TYPE);
-        expect(e.nodeValue).toMatch('0');
+    itRenders('a nested array', async render => {
+      let e = await render([
+        [<div key={1}>text1</div>],
+        <span key={1}>text2</span>,
+        [[[null, <p key={1} />], false]],
+      ]);
+      let parent = e.parentNode;
+      expect(parent.childNodes[0].tagName).toBe('DIV');
+      expect(parent.childNodes[1].tagName).toBe('SPAN');
+      expect(parent.childNodes[2].tagName).toBe('P');
+    });
 
-        // Empty string is special because client renders a node
-        // but server returns empty HTML. So we compare parent text.
-        expect((await render(<div>{''}</div>)).textContent).toBe('');
+    itRenders('an iterable', async render => {
+      const threeDivIterable = {
+        '@@iterator': function() {
+          var i = 0;
+          return {
+            next: function() {
+              if (i++ < 3) {
+                return {value: <div key={i} />, done: false};
+              } else {
+                return {value: undefined, done: true};
+              }
+            },
+          };
+        },
+      };
+      let e = await render(threeDivIterable);
+      let parent = e.parentNode;
+      expect(parent.childNodes.length).toBe(3);
+      expect(parent.childNodes[0].tagName).toBe('DIV');
+      expect(parent.childNodes[1].tagName).toBe('DIV');
+      expect(parent.childNodes[2].tagName).toBe('DIV');
+    });
 
-        expect(await render([])).toBe(null);
-        expect(await render(false)).toBe(null);
-        expect(await render(true)).toBe(null);
-        expect(await render(undefined)).toBe(null);
-        expect(await render([[[false]], undefined])).toBe(null);
-      });
-    }
+    itRenders('emptyish values', async render => {
+      let e = await render(0);
+      expect(e.nodeType).toBe(TEXT_NODE_TYPE);
+      expect(e.nodeValue).toMatch('0');
+
+      // Empty string is special because client renders a node
+      // but server returns empty HTML. So we compare parent text.
+      expect((await render(<div>{''}</div>)).textContent).toBe('');
+
+      expect(await render([])).toBe(null);
+      expect(await render(false)).toBe(null);
+      expect(await render(true)).toBe(null);
+      expect(await render(undefined)).toBe(null);
+      expect(await render([[[false]], undefined])).toBe(null);
+    });
   });
 
   describe('property to attribute mapping', function() {
@@ -976,23 +968,7 @@ describe('ReactDOMServerIntegration', () => {
     }
 
     function expectTextNode(node, text) {
-      if (ReactDOMFeatureFlags.useFiber) {
-        // with Fiber, a React text node is just a DOM text node.
-        expectNode(node, TEXT_NODE_TYPE, text);
-      } else {
-        // with Stack, a React text node is a DOM text node surrounded by
-        // react-text comment nodes.
-        expectNode(node, COMMENT_NODE_TYPE, / react-text: [0-9]+ /);
-        if (text.length > 0) {
-          node = node.nextSibling;
-          expectNode(node, TEXT_NODE_TYPE, text);
-        }
-        expectNode(node.nextSibling, COMMENT_NODE_TYPE, / \/react-text /);
-      }
-    }
-
-    function expectEmptyNode(node) {
-      expectNode(node, COMMENT_NODE_TYPE, / react-empty: [0-9]+ /);
+      expectNode(node, TEXT_NODE_TYPE, text);
     }
 
     describe('text children', function() {
@@ -1017,74 +993,45 @@ describe('ReactDOMServerIntegration', () => {
 
       itRenders('a div with multiple empty text children', async render => {
         const e = await render(<div>{''}{''}{''}</div>);
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there are just three separate text node children,
-          // each of which is blank.
-          if (render === serverRender || render === streamRender) {
-            // For plain server markup result we should have no text nodes if
-            // they're all empty.
-            expect(e.childNodes.length).toBe(0);
-            expect(e.textContent).toBe('');
-          } else {
-            expect(e.childNodes.length).toBe(3);
-            expectTextNode(e.childNodes[0], '');
-            expectTextNode(e.childNodes[1], '');
-            expectTextNode(e.childNodes[2], '');
-          }
+        if (render === serverRender || render === streamRender) {
+          // For plain server markup result we should have no text nodes if
+          // they're all empty.
+          expect(e.childNodes.length).toBe(0);
+          expect(e.textContent).toBe('');
         } else {
-          // with Stack, there are six react-text comment nodes.
-          expect(e.childNodes.length).toBe(6);
+          expect(e.childNodes.length).toBe(3);
           expectTextNode(e.childNodes[0], '');
+          expectTextNode(e.childNodes[1], '');
           expectTextNode(e.childNodes[2], '');
-          expectTextNode(e.childNodes[4], '');
         }
       });
 
       itRenders('a div with multiple whitespace children', async render => {
         const e = await render(<div>{' '}{' '}{' '}</div>);
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there are normally just three text nodes
-          if (
-            render === serverRender ||
-            render === clientRenderOnServerString ||
-            render === streamRender
-          ) {
-            // For plain server markup result we have comments between.
-            // If we're able to hydrate, they remain.
-            expect(e.childNodes.length).toBe(5);
-            expectTextNode(e.childNodes[0], ' ');
-            expectTextNode(e.childNodes[2], ' ');
-            expectTextNode(e.childNodes[4], ' ');
-          } else {
-            expect(e.childNodes.length).toBe(3);
-            expectTextNode(e.childNodes[0], ' ');
-            expectTextNode(e.childNodes[1], ' ');
-            expectTextNode(e.childNodes[2], ' ');
-          }
+        if (
+          render === serverRender ||
+          render === clientRenderOnServerString ||
+          render === streamRender
+        ) {
+          // For plain server markup result we have comments between.
+          // If we're able to hydrate, they remain.
+          expect(e.childNodes.length).toBe(5);
+          expectTextNode(e.childNodes[0], ' ');
+          expectTextNode(e.childNodes[2], ' ');
+          expectTextNode(e.childNodes[4], ' ');
         } else {
-          // with Stack, each of the text nodes is surrounded by react-text
-          // comment nodes, making 9 nodes in total.
-          expect(e.childNodes.length).toBe(9);
+          expect(e.childNodes.length).toBe(3);
           expectTextNode(e.childNodes[0], ' ');
-          expectTextNode(e.childNodes[3], ' ');
-          expectTextNode(e.childNodes[6], ' ');
+          expectTextNode(e.childNodes[1], ' ');
+          expectTextNode(e.childNodes[2], ' ');
         }
       });
 
       itRenders('a div with text sibling to a node', async render => {
         const e = await render(<div>Text<span>More Text</span></div>);
         let spanNode;
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there are only two children, the "Text" text node and
-          // the span element.
-          expect(e.childNodes.length).toBe(2);
-          spanNode = e.childNodes[1];
-        } else {
-          // with Stack, there are four children, a "Text" text node surrounded
-          // by react-text comment nodes, and the span element.
-          expect(e.childNodes.length).toBe(4);
-          spanNode = e.childNodes[3];
-        }
+        expect(e.childNodes.length).toBe(2);
+        spanNode = e.childNodes[1];
         expectTextNode(e.childNodes[0], 'Text');
         expect(spanNode.tagName).toBe('SPAN');
         expect(spanNode.childNodes.length).toBe(1);
@@ -1107,72 +1054,44 @@ describe('ReactDOMServerIntegration', () => {
 
       itRenders('a leading blank child with a text sibling', async render => {
         const e = await render(<div>{''}foo</div>);
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there are just two text nodes.
-          if (render === serverRender || render === streamRender) {
-            expect(e.childNodes.length).toBe(1);
-            expectTextNode(e.childNodes[0], 'foo');
-          } else {
-            expect(e.childNodes.length).toBe(2);
-            expectTextNode(e.childNodes[0], '');
-            expectTextNode(e.childNodes[1], 'foo');
-          }
+        if (render === serverRender || render === streamRender) {
+          expect(e.childNodes.length).toBe(1);
+          expectTextNode(e.childNodes[0], 'foo');
         } else {
-          // with Stack, there are five nodes: two react-text comment nodes
-          // without any text between them, and the text node foo surrounded
-          // by react-text comment nodes.
-          expect(e.childNodes.length).toBe(5);
+          expect(e.childNodes.length).toBe(2);
           expectTextNode(e.childNodes[0], '');
-          expectTextNode(e.childNodes[2], 'foo');
+          expectTextNode(e.childNodes[1], 'foo');
         }
       });
 
       itRenders('a trailing blank child with a text sibling', async render => {
         const e = await render(<div>foo{''}</div>);
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there are just two text nodes.
-          if (render === serverRender || render === streamRender) {
-            expect(e.childNodes.length).toBe(1);
-            expectTextNode(e.childNodes[0], 'foo');
-          } else {
-            expect(e.childNodes.length).toBe(2);
-            expectTextNode(e.childNodes[0], 'foo');
-            expectTextNode(e.childNodes[1], '');
-          }
+        // with Fiber, there are just two text nodes.
+        if (render === serverRender || render === streamRender) {
+          expect(e.childNodes.length).toBe(1);
+          expectTextNode(e.childNodes[0], 'foo');
         } else {
-          // with Stack, there are five nodes: the text node foo surrounded
-          // by react-text comment nodes, and two react-text comment nodes
-          // without any text between them.
-          expect(e.childNodes.length).toBe(5);
+          expect(e.childNodes.length).toBe(2);
           expectTextNode(e.childNodes[0], 'foo');
-          expectTextNode(e.childNodes[3], '');
+          expectTextNode(e.childNodes[1], '');
         }
       });
 
       itRenders('an element with two text children', async render => {
         const e = await render(<div>{'foo'}{'bar'}</div>);
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there are just two text nodes.
-          if (
-            render === serverRender ||
-            render === clientRenderOnServerString ||
-            render === streamRender
-          ) {
-            // In the server render output there's a comment between them.
-            expect(e.childNodes.length).toBe(3);
-            expectTextNode(e.childNodes[0], 'foo');
-            expectTextNode(e.childNodes[2], 'bar');
-          } else {
-            expect(e.childNodes.length).toBe(2);
-            expectTextNode(e.childNodes[0], 'foo');
-            expectTextNode(e.childNodes[1], 'bar');
-          }
+        if (
+          render === serverRender ||
+          render === clientRenderOnServerString ||
+          render === streamRender
+        ) {
+          // In the server render output there's a comment between them.
+          expect(e.childNodes.length).toBe(3);
+          expectTextNode(e.childNodes[0], 'foo');
+          expectTextNode(e.childNodes[2], 'bar');
         } else {
-          // with Stack, there are six nodes: two text nodes, each surrounded
-          // by react-text comment nodes.
-          expect(e.childNodes.length).toBe(6);
+          expect(e.childNodes.length).toBe(2);
           expectTextNode(e.childNodes[0], 'foo');
-          expectTextNode(e.childNodes[3], 'bar');
+          expectTextNode(e.childNodes[1], 'bar');
         }
       });
     });
@@ -1191,28 +1110,20 @@ describe('ReactDOMServerIntegration', () => {
 
       itRenders('an element with number and text children', async render => {
         const e = await render(<div>{'foo'}{40}</div>);
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there are just two text nodes.
-          if (
-            render === serverRender ||
-            render === clientRenderOnServerString ||
-            render === streamRender
-          ) {
-            // In the server markup there's a comment between.
-            expect(e.childNodes.length).toBe(3);
-            expectTextNode(e.childNodes[0], 'foo');
-            expectTextNode(e.childNodes[2], '40');
-          } else {
-            expect(e.childNodes.length).toBe(2);
-            expectTextNode(e.childNodes[0], 'foo');
-            expectTextNode(e.childNodes[1], '40');
-          }
+        // with Fiber, there are just two text nodes.
+        if (
+          render === serverRender ||
+          render === clientRenderOnServerString ||
+          render === streamRender
+        ) {
+          // In the server markup there's a comment between.
+          expect(e.childNodes.length).toBe(3);
+          expectTextNode(e.childNodes[0], 'foo');
+          expectTextNode(e.childNodes[2], '40');
         } else {
-          // with Stack, there are six nodes: two text nodes, each surrounded
-          // by react-text comment nodes.
-          expect(e.childNodes.length).toBe(6);
+          expect(e.childNodes.length).toBe(2);
           expectTextNode(e.childNodes[0], 'foo');
-          expectTextNode(e.childNodes[3], '40');
+          expectTextNode(e.childNodes[1], '40');
         }
       });
     });
@@ -1236,54 +1147,25 @@ describe('ReactDOMServerIntegration', () => {
       itRenders('a null component children as empty', async render => {
         const NullComponent = () => null;
         const e = await render(<div><NullComponent /></div>);
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, an empty component results in no markup.
-          expect(e.childNodes.length).toBe(0);
-        } else {
-          // with Stack, an empty component results in one react-empty comment
-          // node.
-          expect(e.childNodes.length).toBe(1);
-          expectEmptyNode(e.firstChild);
-        }
+        expect(e.childNodes.length).toBe(0);
       });
 
       itRenders('null children as blank', async render => {
         const e = await render(<div>{null}foo</div>);
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there is just one text node.
-          expect(e.childNodes.length).toBe(1);
-          expectTextNode(e.childNodes[0], 'foo');
-        } else {
-          // with Stack, there's a text node surronded by react-text comment nodes.
-          expect(e.childNodes.length).toBe(3);
-          expectTextNode(e.childNodes[0], 'foo');
-        }
+        expect(e.childNodes.length).toBe(1);
+        expectTextNode(e.childNodes[0], 'foo');
       });
 
       itRenders('false children as blank', async render => {
         const e = await render(<div>{false}foo</div>);
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there is just one text node.
-          expect(e.childNodes.length).toBe(1);
-          expectTextNode(e.childNodes[0], 'foo');
-        } else {
-          // with Stack, there's a text node surronded by react-text comment nodes.
-          expect(e.childNodes.length).toBe(3);
-          expectTextNode(e.childNodes[0], 'foo');
-        }
+        expect(e.childNodes.length).toBe(1);
+        expectTextNode(e.childNodes[0], 'foo');
       });
 
       itRenders('null and false children together as blank', async render => {
         const e = await render(<div>{false}{null}foo{null}{false}</div>);
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there is just one text node.
-          expect(e.childNodes.length).toBe(1);
-          expectTextNode(e.childNodes[0], 'foo');
-        } else {
-          // with Stack, there's a text node surronded by react-text comment nodes.
-          expect(e.childNodes.length).toBe(3);
-          expectTextNode(e.childNodes[0], 'foo');
-        }
+        expect(e.childNodes.length).toBe(1);
+        expectTextNode(e.childNodes[0], 'foo');
       });
 
       itRenders('only null and false children as blank', async render => {
@@ -1488,21 +1370,10 @@ describe('ReactDOMServerIntegration', () => {
           );
           expect(e.id).toBe('parent');
           let child1, child2, textNode;
-          if (ReactDOMFeatureFlags.useFiber) {
-            // with Fiber, there are three children: the child1 element, a
-            // single space text node, and the child2 element.
-            expect(e.childNodes.length).toBe(3);
-            child1 = e.childNodes[0];
-            textNode = e.childNodes[1];
-            child2 = e.childNodes[2];
-          } else {
-            // with Stack, there are five children: the child1 element, a single
-            // space surrounded by react-text comments, and the child2 element.
-            expect(e.childNodes.length).toBe(5);
-            child1 = e.childNodes[0];
-            textNode = e.childNodes[1];
-            child2 = e.childNodes[4];
-          }
+          expect(e.childNodes.length).toBe(3);
+          child1 = e.childNodes[0];
+          textNode = e.childNodes[1];
+          child2 = e.childNodes[2];
           expect(child1.id).toBe('child1');
           expect(child1.childNodes.length).toBe(0);
           expectTextNode(textNode, ' ');
@@ -1517,22 +1388,10 @@ describe('ReactDOMServerIntegration', () => {
           // prettier-ignore
           const e = await render(<div id="parent">  <div id="child" />   </div>); // eslint-disable-line no-multi-spaces
           let textNode1, child, textNode2;
-          if (ReactDOMFeatureFlags.useFiber) {
-            // with Fiber, there are three children: a one-space text node, the
-            // child element, and a two-space text node.
-            expect(e.childNodes.length).toBe(3);
-            textNode1 = e.childNodes[0];
-            child = e.childNodes[1];
-            textNode2 = e.childNodes[2];
-          } else {
-            // with Stack, there are 7 children: a one-space text node surrounded
-            // by react-text comments, the child element, and a two-space text node
-            // surrounded by react-text comments.
-            expect(e.childNodes.length).toBe(7);
-            textNode1 = e.childNodes[0];
-            child = e.childNodes[3];
-            textNode2 = e.childNodes[4];
-          }
+          expect(e.childNodes.length).toBe(3);
+          textNode1 = e.childNodes[0];
+          child = e.childNodes[1];
+          textNode2 = e.childNodes[2];
           expect(e.id).toBe('parent');
           expectTextNode(textNode1, '  ');
           expect(child.id).toBe('child');
@@ -1541,33 +1400,31 @@ describe('ReactDOMServerIntegration', () => {
         },
       );
 
-      if (ReactDOMFeatureFlags.useFiber) {
-        itRenders('a composite with multiple children', async render => {
-          const Component = props => props.children;
-          const e = await render(
-            <Component>{['a', 'b', [undefined], [[false, 'c']]]}</Component>,
-          );
+      itRenders('a composite with multiple children', async render => {
+        const Component = props => props.children;
+        const e = await render(
+          <Component>{['a', 'b', [undefined], [[false, 'c']]]}</Component>,
+        );
 
-          let parent = e.parentNode;
-          if (
-            render === serverRender ||
-            render === clientRenderOnServerString ||
-            render === streamRender
-          ) {
-            // For plain server markup result we have comments between.
-            // If we're able to hydrate, they remain.
-            expect(parent.childNodes.length).toBe(5);
-            expectTextNode(parent.childNodes[0], 'a');
-            expectTextNode(parent.childNodes[2], 'b');
-            expectTextNode(parent.childNodes[4], 'c');
-          } else {
-            expect(parent.childNodes.length).toBe(3);
-            expectTextNode(parent.childNodes[0], 'a');
-            expectTextNode(parent.childNodes[1], 'b');
-            expectTextNode(parent.childNodes[2], 'c');
-          }
-        });
-      }
+        let parent = e.parentNode;
+        if (
+          render === serverRender ||
+          render === clientRenderOnServerString ||
+          render === streamRender
+        ) {
+          // For plain server markup result we have comments between.
+          // If we're able to hydrate, they remain.
+          expect(parent.childNodes.length).toBe(5);
+          expectTextNode(parent.childNodes[0], 'a');
+          expectTextNode(parent.childNodes[2], 'b');
+          expectTextNode(parent.childNodes[4], 'c');
+        } else {
+          expect(parent.childNodes.length).toBe(3);
+          expectTextNode(parent.childNodes[0], 'a');
+          expectTextNode(parent.childNodes[1], 'b');
+          expectTextNode(parent.childNodes[2], 'c');
+        }
+      });
     });
 
     describe('escaping >, <, and &', function() {
@@ -1581,27 +1438,18 @@ describe('ReactDOMServerIntegration', () => {
         const e = await render(
           <div>{'<span>Text1&quot;</span>'}{'<span>Text2&quot;</span>'}</div>,
         );
-        if (ReactDOMFeatureFlags.useFiber) {
-          // with Fiber, there are just two text nodes.
-          if (
-            render === serverRender ||
-            render === clientRenderOnServerString ||
-            render === streamRender
-          ) {
-            expect(e.childNodes.length).toBe(3);
-            expectTextNode(e.childNodes[0], '<span>Text1&quot;</span>');
-            expectTextNode(e.childNodes[2], '<span>Text2&quot;</span>');
-          } else {
-            expect(e.childNodes.length).toBe(2);
-            expectTextNode(e.childNodes[0], '<span>Text1&quot;</span>');
-            expectTextNode(e.childNodes[1], '<span>Text2&quot;</span>');
-          }
+        if (
+          render === serverRender ||
+          render === clientRenderOnServerString ||
+          render === streamRender
+        ) {
+          expect(e.childNodes.length).toBe(3);
+          expectTextNode(e.childNodes[0], '<span>Text1&quot;</span>');
+          expectTextNode(e.childNodes[2], '<span>Text2&quot;</span>');
         } else {
-          // with Stack there are six nodes: two text nodes each surrounded by
-          // two react-text comment nodes.
-          expect(e.childNodes.length).toBe(6);
+          expect(e.childNodes.length).toBe(2);
           expectTextNode(e.childNodes[0], '<span>Text1&quot;</span>');
-          expectTextNode(e.childNodes[3], '<span>Text2&quot;</span>');
+          expectTextNode(e.childNodes[1], '<span>Text2&quot;</span>');
         }
       });
     });
@@ -1613,12 +1461,9 @@ describe('ReactDOMServerIntegration', () => {
           const UndefinedComponent = () => undefined;
           await render(<UndefinedComponent />, 1);
         },
-        ReactDOMFeatureFlags.useFiber
-          ? 'UndefinedComponent(...): Nothing was returned from render. ' +
-              'This usually means a return statement is missing. Or, to ' +
-              'render nothing, return null.'
-          : 'A valid React element (or null) must be returned. ' +
-              'You may have returned undefined, an array or some other invalid object.',
+        'UndefinedComponent(...): Nothing was returned from render. ' +
+          'This usually means a return statement is missing. Or, to ' +
+          'render nothing, return null.',
       );
 
       itThrowsWhenRendering(
@@ -1631,12 +1476,9 @@ describe('ReactDOMServerIntegration', () => {
           }
           await render(<UndefinedComponent />, 1);
         },
-        ReactDOMFeatureFlags.useFiber
-          ? 'UndefinedComponent(...): Nothing was returned from render. ' +
-              'This usually means a return statement is missing. Or, to ' +
-              'render nothing, return null.'
-          : 'A valid React element (or null) must be returned. ' +
-              'You may have returned undefined, an array or some other invalid object.',
+        'UndefinedComponent(...): Nothing was returned from render. ' +
+          'This usually means a return statement is missing. Or, to ' +
+          'render nothing, return null.',
       );
 
       itThrowsWhenRendering(
@@ -1645,12 +1487,9 @@ describe('ReactDOMServerIntegration', () => {
           const ObjectComponent = () => ({x: 123});
           await render(<ObjectComponent />, 1);
         },
-        ReactDOMFeatureFlags.useFiber
-          ? 'Objects are not valid as a React child (found: object with keys ' +
-              '{x}). If you meant to render a collection of children, use ' +
-              'an array instead.'
-          : 'A valid React element (or null) must be returned. ' +
-              'You may have returned undefined, an array or some other invalid object.',
+        'Objects are not valid as a React child (found: object with keys ' +
+          '{x}). If you meant to render a collection of children, use ' +
+          'an array instead.',
       );
 
       itThrowsWhenRendering(
@@ -1663,12 +1502,9 @@ describe('ReactDOMServerIntegration', () => {
           }
           await render(<ObjectComponent />, 1);
         },
-        ReactDOMFeatureFlags.useFiber
-          ? 'Objects are not valid as a React child (found: object with keys ' +
-              '{x}). If you meant to render a collection of children, use ' +
-              'an array instead.'
-          : 'A valid React element (or null) must be returned. ' +
-              'You may have returned undefined, an array or some other invalid object.',
+        'Objects are not valid as a React child (found: object with keys ' +
+          '{x}). If you meant to render a collection of children, use ' +
+          'an array instead.',
       );
 
       itThrowsWhenRendering(
@@ -1676,11 +1512,9 @@ describe('ReactDOMServerIntegration', () => {
         async render => {
           await render({x: 123});
         },
-        ReactDOMFeatureFlags.useFiber
-          ? 'Objects are not valid as a React child (found: object with keys ' +
-              '{x}). If you meant to render a collection of children, use ' +
-              'an array instead.'
-          : 'Invalid component element.',
+        'Objects are not valid as a React child (found: object with keys ' +
+          '{x}). If you meant to render a collection of children, use ' +
+          'an array instead.',
       );
     });
   });
@@ -2700,12 +2534,7 @@ describe('ReactDOMServerIntegration', () => {
         ));
 
       it('can distinguish an empty component from an empty text component', () =>
-        (ReactDOMFeatureFlags.useFiber
-          ? expectMarkupMatch
-          : expectMarkupMismatch)(
-          <div><EmptyComponent /></div>,
-          <div>{''}</div>,
-        ));
+        expectMarkupMatch(<div><EmptyComponent /></div>, <div>{''}</div>));
     });
 
     // Markup Mismatches: misc
diff --git a/src/renderers/dom/shared/__tests__/ReactDOMTextComponent-test.js b/src/renderers/dom/shared/__tests__/ReactDOMTextComponent-test.js
index 28a2196a020..0f7662b236b 100644
--- a/src/renderers/dom/shared/__tests__/ReactDOMTextComponent-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactDOMTextComponent-test.js
@@ -14,7 +14,6 @@
 var React;
 var ReactDOM;
 var ReactDOMServer;
-var ReactDOMFeatureFlags;
 
 // In standard React, TextComponent keeps track of different Text templates
 // using comments. However, in React Fiber, those comments are not outputted due
@@ -30,7 +29,6 @@ describe('ReactDOMTextComponent', () => {
     React = require('react');
     ReactDOM = require('react-dom');
     ReactDOMServer = require('react-dom/server');
-    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
   });
 
   it('updates a mounted text component in place', () => {
@@ -119,11 +117,7 @@ describe('ReactDOMTextComponent', () => {
     var reactEl = <div>{'foo'}{'bar'}{'baz'}</div>;
     el.innerHTML = ReactDOMServer.renderToString(reactEl);
 
-    if (ReactDOMFeatureFlags.useFiber) {
-      ReactDOM.hydrate(reactEl, el);
-    } else {
-      ReactDOM.render(reactEl, el);
-    }
+    ReactDOM.hydrate(reactEl, el);
     expect(el.textContent).toBe('foobarbaz');
 
     ReactDOM.unmountComponentAtNode(el);
@@ -131,11 +125,7 @@ describe('ReactDOMTextComponent', () => {
     reactEl = <div>{''}{''}{''}</div>;
     el.innerHTML = ReactDOMServer.renderToString(reactEl);
 
-    if (ReactDOMFeatureFlags.useFiber) {
-      ReactDOM.hydrate(reactEl, el);
-    } else {
-      ReactDOM.render(reactEl, el);
-    }
+    ReactDOM.hydrate(reactEl, el);
     expect(el.textContent).toBe('');
   });
 
diff --git a/src/renderers/dom/shared/__tests__/ReactMount-test.js b/src/renderers/dom/shared/__tests__/ReactMount-test.js
index 458cbd09ff9..3d404de2bac 100644
--- a/src/renderers/dom/shared/__tests__/ReactMount-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactMount-test.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-const ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 const {COMMENT_NODE} = require('HTMLNodeType');
 
 const invariant = require('invariant');
@@ -151,21 +150,11 @@ describe('ReactMount', () => {
     container.innerHTML = ReactDOMServer.renderToString(<div />) + ' ';
 
     spyOn(console, 'error');
-    if (ReactDOMFeatureFlags.useFiber) {
-      ReactDOM.hydrate(<div />, container);
-    } else {
-      ReactDOM.render(<div />, container);
-    }
+    ReactDOM.hydrate(<div />, container);
     expectDev(console.error.calls.count()).toBe(1);
-    if (ReactDOMFeatureFlags.useFiber) {
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'Did not expect server HTML to contain the text node " " in <container>.',
-      );
-    } else {
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'Target node has markup rendered by React, but there are unrelated nodes as well.',
-      );
-    }
+    expectDev(console.error.calls.argsFor(0)[0]).toContain(
+      'Did not expect server HTML to contain the text node " " in <container>.',
+    );
   });
 
   it('should warn if mounting into right padded rendered markup', () => {
@@ -173,21 +162,11 @@ describe('ReactMount', () => {
     container.innerHTML = ' ' + ReactDOMServer.renderToString(<div />);
 
     spyOn(console, 'error');
-    if (ReactDOMFeatureFlags.useFiber) {
-      ReactDOM.hydrate(<div />, container);
-    } else {
-      ReactDOM.render(<div />, container);
-    }
+    ReactDOM.hydrate(<div />, container);
     expectDev(console.error.calls.count()).toBe(1);
-    if (ReactDOMFeatureFlags.useFiber) {
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'Did not expect server HTML to contain the text node " " in <container>.',
-      );
-    } else {
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'Target node has markup rendered by React, but there are unrelated nodes as well.',
-      );
-    }
+    expectDev(console.error.calls.argsFor(0)[0]).toContain(
+      'Did not expect server HTML to contain the text node " " in <container>.',
+    );
   });
 
   it('should not warn if mounting into non-empty node', () => {
@@ -220,29 +199,15 @@ describe('ReactMount', () => {
     div.innerHTML = markup;
 
     spyOn(console, 'error');
-    if (ReactDOMFeatureFlags.useFiber) {
-      ReactDOM.hydrate(
-        <div>This markup contains an nbsp entity: &nbsp; client text</div>,
-        div,
-      );
-    } else {
-      ReactDOM.render(
-        <div>This markup contains an nbsp entity: &nbsp; client text</div>,
-        div,
-      );
-    }
+    ReactDOM.hydrate(
+      <div>This markup contains an nbsp entity: &nbsp; client text</div>,
+      div,
+    );
     expectDev(console.error.calls.count()).toBe(1);
-    if (ReactDOMFeatureFlags.useFiber) {
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'Server: "This markup contains an nbsp entity:   server text" ' +
-          'Client: "This markup contains an nbsp entity:   client text"',
-      );
-    } else {
-      expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        ' (client) nbsp entity: &nbsp; client text</div>\n' +
-          ' (server) nbsp entity: &nbsp; server text</div>',
-      );
-    }
+    expectDev(console.error.calls.argsFor(0)[0]).toContain(
+      'Server: "This markup contains an nbsp entity:   server text" ' +
+        'Client: "This markup contains an nbsp entity:   client text"',
+    );
   });
 
   if (WebComponents !== undefined) {
@@ -395,44 +360,42 @@ describe('ReactMount', () => {
     expect(container2.textContent).toEqual('a!');
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    describe('mount point is a comment node', () => {
-      let containerDiv;
-      let mountPoint;
+  describe('mount point is a comment node', () => {
+    let containerDiv;
+    let mountPoint;
 
-      beforeEach(() => {
-        const ReactFeatureFlags = require('ReactFeatureFlags');
-        ReactFeatureFlags.disableNewFiberFeatures = false;
+    beforeEach(() => {
+      const ReactFeatureFlags = require('ReactFeatureFlags');
+      ReactFeatureFlags.disableNewFiberFeatures = false;
 
-        containerDiv = document.createElement('div');
-        containerDiv.innerHTML = 'A<!-- react-mount-point-unstable -->B';
-        mountPoint = containerDiv.childNodes[1];
-        invariant(mountPoint.nodeType === COMMENT_NODE, 'Expected comment');
-      });
+      containerDiv = document.createElement('div');
+      containerDiv.innerHTML = 'A<!-- react-mount-point-unstable -->B';
+      mountPoint = containerDiv.childNodes[1];
+      invariant(mountPoint.nodeType === COMMENT_NODE, 'Expected comment');
+    });
 
-      it('renders at a comment node', () => {
-        function Char(props) {
-          return props.children;
-        }
-        function list(chars) {
-          return chars.split('').map(c => <Char key={c}>{c}</Char>);
-        }
-
-        ReactDOM.render(list('aeiou'), mountPoint);
-        expect(containerDiv.innerHTML).toBe(
-          'Aaeiou<!-- react-mount-point-unstable -->B',
-        );
+    it('renders at a comment node', () => {
+      function Char(props) {
+        return props.children;
+      }
+      function list(chars) {
+        return chars.split('').map(c => <Char key={c}>{c}</Char>);
+      }
 
-        ReactDOM.render(list('yea'), mountPoint);
-        expect(containerDiv.innerHTML).toBe(
-          'Ayea<!-- react-mount-point-unstable -->B',
-        );
+      ReactDOM.render(list('aeiou'), mountPoint);
+      expect(containerDiv.innerHTML).toBe(
+        'Aaeiou<!-- react-mount-point-unstable -->B',
+      );
 
-        ReactDOM.render(list(''), mountPoint);
-        expect(containerDiv.innerHTML).toBe(
-          'A<!-- react-mount-point-unstable -->B',
-        );
-      });
+      ReactDOM.render(list('yea'), mountPoint);
+      expect(containerDiv.innerHTML).toBe(
+        'Ayea<!-- react-mount-point-unstable -->B',
+      );
+
+      ReactDOM.render(list(''), mountPoint);
+      expect(containerDiv.innerHTML).toBe(
+        'A<!-- react-mount-point-unstable -->B',
+      );
     });
-  }
+  });
 });
diff --git a/src/renderers/dom/shared/__tests__/ReactRenderDocument-test.js b/src/renderers/dom/shared/__tests__/ReactRenderDocument-test.js
index c5f1de4e463..521cccda52a 100644
--- a/src/renderers/dom/shared/__tests__/ReactRenderDocument-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactRenderDocument-test.js
@@ -17,15 +17,6 @@ var ReactDOMServer;
 
 var getTestDocument;
 
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-
-var UNMOUNT_INVARIANT_MESSAGE =
-  '<html> tried to unmount. ' +
-  'Because of cross-browser quirks it is impossible to unmount some ' +
-  'top-level components (eg <html>, <head>, and <body>) reliably and ' +
-  'efficiently. To fix this, have a single top-level component that ' +
-  'never unmounts render these elements.';
-
 describe('rendering React components at document', () => {
   beforeEach(() => {
     jest.resetModules();
@@ -38,16 +29,12 @@ describe('rendering React components at document', () => {
 
   describe('with old implicit hydration API', () => {
     function expectDeprecationWarningWithFiber() {
-      if (ReactDOMFeatureFlags.useFiber) {
-        expectDev(console.warn.calls.count()).toBe(1);
-        expectDev(console.warn.calls.argsFor(0)[0]).toContain(
-          'render(): Calling ReactDOM.render() to hydrate server-rendered markup ' +
-            'will stop working in React v17. Replace the ReactDOM.render() call ' +
-            'with ReactDOM.hydrate() if you want React to attach to the server HTML.',
-        );
-      } else {
-        expectDev(console.warn.calls.count()).toBe(0);
-      }
+      expectDev(console.warn.calls.count()).toBe(1);
+      expectDev(console.warn.calls.argsFor(0)[0]).toContain(
+        'render(): Calling ReactDOM.render() to hydrate server-rendered markup ' +
+          'will stop working in React v17. Replace the ReactDOM.render() call ' +
+          'with ReactDOM.hydrate() if you want React to attach to the server HTML.',
+      );
     }
 
     it('should be able to adopt server markup', () => {
@@ -103,17 +90,9 @@ describe('rendering React components at document', () => {
       ReactDOM.render(<Root />, testDocument);
       expect(testDocument.body.innerHTML).toBe('Hello world');
 
-      if (ReactDOMFeatureFlags.useFiber) {
-        // In Fiber this actually works. It might not be a good idea though.
-        ReactDOM.unmountComponentAtNode(testDocument);
-        expect(testDocument.firstChild).toBe(null);
-      } else {
-        expect(function() {
-          ReactDOM.unmountComponentAtNode(testDocument);
-        }).toThrowError(UNMOUNT_INVARIANT_MESSAGE);
-
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-      }
+      // In Fiber this actually works. It might not be a good idea though.
+      ReactDOM.unmountComponentAtNode(testDocument);
+      expect(testDocument.firstChild).toBe(null);
 
       expectDeprecationWarningWithFiber();
     });
@@ -154,23 +133,12 @@ describe('rendering React components at document', () => {
       var testDocument = getTestDocument(markup);
 
       ReactDOM.render(<Component />, testDocument);
-
       expect(testDocument.body.innerHTML).toBe('Hello world');
 
-      // Reactive update
-      if (ReactDOMFeatureFlags.useFiber) {
-        // This works but is probably a bad idea.
-        ReactDOM.render(<Component2 />, testDocument);
-
-        expect(testDocument.body.innerHTML).toBe('Goodbye world');
-      } else {
-        expect(function() {
-          ReactDOM.render(<Component2 />, testDocument);
-        }).toThrowError(UNMOUNT_INVARIANT_MESSAGE);
-
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-      }
+      // This works but is probably a bad idea.
+      ReactDOM.render(<Component2 />, testDocument);
 
+      expect(testDocument.body.innerHTML).toBe('Goodbye world');
       expectDeprecationWarningWithFiber();
     });
 
@@ -233,38 +201,20 @@ describe('rendering React components at document', () => {
       );
       var testDocument = getTestDocument(markup);
 
-      if (ReactDOMFeatureFlags.useFiber) {
-        spyOn(console, 'warn');
-        spyOn(console, 'error');
-        ReactDOM.render(<Component text="Hello world" />, testDocument);
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-        expectDev(console.warn.calls.count()).toBe(1);
-        expectDev(console.warn.calls.argsFor(0)[0]).toContain(
-          'render(): Calling ReactDOM.render() to hydrate server-rendered markup ' +
-            'will stop working in React v17. Replace the ReactDOM.render() call ' +
-            'with ReactDOM.hydrate() if you want React to attach to the server HTML.',
-        );
-        expectDev(console.error.calls.count()).toBe(1);
-        expectDev(console.error.calls.argsFor(0)[0]).toContain(
-          'Warning: Text content did not match.',
-        );
-      } else {
-        expect(function() {
-          // Notice the text is different!
-          ReactDOM.render(<Component text="Hello world" />, testDocument);
-        }).toThrowError(
-          "You're trying to render a component to the document using " +
-            'server rendering but the checksum was invalid. This usually ' +
-            'means you rendered a different component type or props on ' +
-            'the client from the one on the server, or your render() methods ' +
-            'are impure. React cannot handle this case due to cross-browser ' +
-            'quirks by rendering at the document root. You should look for ' +
-            'environment dependent code in your components and ensure ' +
-            'the props are the same client and server side:\n' +
-            ' (client) dy data-reactid="4">Hello world</body></\n' +
-            ' (server) dy data-reactid="4">Goodbye world</body>',
-        );
-      }
+      spyOn(console, 'warn');
+      spyOn(console, 'error');
+      ReactDOM.render(<Component text="Hello world" />, testDocument);
+      expect(testDocument.body.innerHTML).toBe('Hello world');
+      expectDev(console.warn.calls.count()).toBe(1);
+      expectDev(console.warn.calls.argsFor(0)[0]).toContain(
+        'render(): Calling ReactDOM.render() to hydrate server-rendered markup ' +
+          'will stop working in React v17. Replace the ReactDOM.render() call ' +
+          'with ReactDOM.hydrate() if you want React to attach to the server HTML.',
+      );
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(console.error.calls.argsFor(0)[0]).toContain(
+        'Warning: Text content did not match.',
+      );
     });
 
     it('should throw on full document render w/ no markup', () => {
@@ -285,19 +235,8 @@ describe('rendering React components at document', () => {
         }
       }
 
-      if (ReactDOMFeatureFlags.useFiber) {
-        ReactDOM.render(<Component text="Hello world" />, testDocument);
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-      } else {
-        expect(function() {
-          ReactDOM.render(<Component />, testDocument);
-        }).toThrowError(
-          "You're trying to render a component to the document but you didn't " +
-            "use server rendering. We can't do this without using server " +
-            'rendering due to cross-browser quirks. See ' +
-            'ReactDOMServer.renderToString() for server rendering.',
-        );
-      }
+      ReactDOM.render(<Component text="Hello world" />, testDocument);
+      expect(testDocument.body.innerHTML).toBe('Hello world');
       // We don't expect a warning about new hydration API here because
       // we aren't sure if the user meant to hydrate or replace the document.
       // We would see a warning if the document had React-rendered HTML in it.
@@ -325,221 +264,219 @@ describe('rendering React components at document', () => {
     });
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    describe('with new explicit hydration API', () => {
-      it('should be able to adopt server markup', () => {
-        class Root extends React.Component {
-          render() {
-            return (
-              <html>
-                <head>
-                  <title>Hello World</title>
-                </head>
-                <body>
-                  {'Hello ' + this.props.hello}
-                </body>
-              </html>
-            );
-          }
+  describe('with new explicit hydration API', () => {
+    it('should be able to adopt server markup', () => {
+      class Root extends React.Component {
+        render() {
+          return (
+            <html>
+              <head>
+                <title>Hello World</title>
+              </head>
+              <body>
+                {'Hello ' + this.props.hello}
+              </body>
+            </html>
+          );
         }
+      }
+
+      var markup = ReactDOMServer.renderToString(<Root hello="world" />);
+      var testDocument = getTestDocument(markup);
+      var body = testDocument.body;
+
+      ReactDOM.hydrate(<Root hello="world" />, testDocument);
+      expect(testDocument.body.innerHTML).toBe('Hello world');
+
+      ReactDOM.hydrate(<Root hello="moon" />, testDocument);
+      expect(testDocument.body.innerHTML).toBe('Hello moon');
+
+      expect(body === testDocument.body).toBe(true);
+    });
 
-        var markup = ReactDOMServer.renderToString(<Root hello="world" />);
-        var testDocument = getTestDocument(markup);
-        var body = testDocument.body;
-
-        ReactDOM.hydrate(<Root hello="world" />, testDocument);
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-
-        ReactDOM.hydrate(<Root hello="moon" />, testDocument);
-        expect(testDocument.body.innerHTML).toBe('Hello moon');
-
-        expect(body === testDocument.body).toBe(true);
-      });
-
-      it('should not be able to unmount component from document node', () => {
-        class Root extends React.Component {
-          render() {
-            return (
-              <html>
-                <head>
-                  <title>Hello World</title>
-                </head>
-                <body>
-                  Hello world
-                </body>
-              </html>
-            );
-          }
+    it('should not be able to unmount component from document node', () => {
+      class Root extends React.Component {
+        render() {
+          return (
+            <html>
+              <head>
+                <title>Hello World</title>
+              </head>
+              <body>
+                Hello world
+              </body>
+            </html>
+          );
         }
+      }
+
+      var markup = ReactDOMServer.renderToString(<Root />);
+      var testDocument = getTestDocument(markup);
+      ReactDOM.hydrate(<Root />, testDocument);
+      expect(testDocument.body.innerHTML).toBe('Hello world');
+
+      // In Fiber this actually works. It might not be a good idea though.
+      ReactDOM.unmountComponentAtNode(testDocument);
+      expect(testDocument.firstChild).toBe(null);
+    });
 
-        var markup = ReactDOMServer.renderToString(<Root />);
-        var testDocument = getTestDocument(markup);
-        ReactDOM.hydrate(<Root />, testDocument);
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-
-        // In Fiber this actually works. It might not be a good idea though.
-        ReactDOM.unmountComponentAtNode(testDocument);
-        expect(testDocument.firstChild).toBe(null);
-      });
-
-      it('should not be able to switch root constructors', () => {
-        class Component extends React.Component {
-          render() {
-            return (
-              <html>
-                <head>
-                  <title>Hello World</title>
-                </head>
-                <body>
-                  Hello world
-                </body>
-              </html>
-            );
-          }
+    it('should not be able to switch root constructors', () => {
+      class Component extends React.Component {
+        render() {
+          return (
+            <html>
+              <head>
+                <title>Hello World</title>
+              </head>
+              <body>
+                Hello world
+              </body>
+            </html>
+          );
         }
+      }
 
-        class Component2 extends React.Component {
-          render() {
-            return (
-              <html>
-                <head>
-                  <title>Hello World</title>
-                </head>
-                <body>
-                  Goodbye world
-                </body>
-              </html>
-            );
-          }
+      class Component2 extends React.Component {
+        render() {
+          return (
+            <html>
+              <head>
+                <title>Hello World</title>
+              </head>
+              <body>
+                Goodbye world
+              </body>
+            </html>
+          );
         }
+      }
+
+      var markup = ReactDOMServer.renderToString(<Component />);
+      var testDocument = getTestDocument(markup);
+
+      ReactDOM.hydrate(<Component />, testDocument);
 
-        var markup = ReactDOMServer.renderToString(<Component />);
-        var testDocument = getTestDocument(markup);
-
-        ReactDOM.hydrate(<Component />, testDocument);
-
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-
-        // This works but is probably a bad idea.
-        ReactDOM.hydrate(<Component2 />, testDocument);
-
-        expect(testDocument.body.innerHTML).toBe('Goodbye world');
-      });
-
-      it('should be able to mount into document', () => {
-        class Component extends React.Component {
-          render() {
-            return (
-              <html>
-                <head>
-                  <title>Hello World</title>
-                </head>
-                <body>
-                  {this.props.text}
-                </body>
-              </html>
-            );
-          }
+      expect(testDocument.body.innerHTML).toBe('Hello world');
+
+      // This works but is probably a bad idea.
+      ReactDOM.hydrate(<Component2 />, testDocument);
+
+      expect(testDocument.body.innerHTML).toBe('Goodbye world');
+    });
+
+    it('should be able to mount into document', () => {
+      class Component extends React.Component {
+        render() {
+          return (
+            <html>
+              <head>
+                <title>Hello World</title>
+              </head>
+              <body>
+                {this.props.text}
+              </body>
+            </html>
+          );
         }
+      }
+
+      var markup = ReactDOMServer.renderToString(
+        <Component text="Hello world" />,
+      );
+      var testDocument = getTestDocument(markup);
 
-        var markup = ReactDOMServer.renderToString(
-          <Component text="Hello world" />,
-        );
-        var testDocument = getTestDocument(markup);
-
-        ReactDOM.hydrate(<Component text="Hello world" />, testDocument);
-
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-      });
-
-      it('renders over an existing text child without throwing', () => {
-        spyOn(console, 'error');
-        const container = document.createElement('div');
-        container.textContent = 'potato';
-        ReactDOM.hydrate(<div>parsnip</div>, container);
-        expect(container.textContent).toBe('parsnip');
-        expectDev(console.error.calls.count()).toBe(1);
-        expectDev(console.error.calls.argsFor(0)[0]).toContain(
-          'Did not expect server HTML to contain the text node "potato" in <div>.',
-        );
-      });
-
-      it('should give helpful errors on state desync', () => {
-        class Component extends React.Component {
-          render() {
-            return (
-              <html>
-                <head>
-                  <title>Hello World</title>
-                </head>
-                <body>
-                  {this.props.text}
-                </body>
-              </html>
-            );
-          }
+      ReactDOM.hydrate(<Component text="Hello world" />, testDocument);
+
+      expect(testDocument.body.innerHTML).toBe('Hello world');
+    });
+
+    it('renders over an existing text child without throwing', () => {
+      spyOn(console, 'error');
+      const container = document.createElement('div');
+      container.textContent = 'potato';
+      ReactDOM.hydrate(<div>parsnip</div>, container);
+      expect(container.textContent).toBe('parsnip');
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(console.error.calls.argsFor(0)[0]).toContain(
+        'Did not expect server HTML to contain the text node "potato" in <div>.',
+      );
+    });
+
+    it('should give helpful errors on state desync', () => {
+      class Component extends React.Component {
+        render() {
+          return (
+            <html>
+              <head>
+                <title>Hello World</title>
+              </head>
+              <body>
+                {this.props.text}
+              </body>
+            </html>
+          );
         }
+      }
+
+      var markup = ReactDOMServer.renderToString(
+        <Component text="Goodbye world" />,
+      );
+      var testDocument = getTestDocument(markup);
+
+      spyOn(console, 'error');
+      ReactDOM.hydrate(<Component text="Hello world" />, testDocument);
+      expect(testDocument.body.innerHTML).toBe('Hello world');
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(console.error.calls.argsFor(0)[0]).toContain(
+        'Warning: Text content did not match.',
+      );
+    });
+
+    it('should render w/ no markup to full document', () => {
+      spyOn(console, 'error');
+      var testDocument = getTestDocument();
 
-        var markup = ReactDOMServer.renderToString(
-          <Component text="Goodbye world" />,
-        );
-        var testDocument = getTestDocument(markup);
-
-        spyOn(console, 'error');
-        ReactDOM.hydrate(<Component text="Hello world" />, testDocument);
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-        expectDev(console.error.calls.count()).toBe(1);
-        expectDev(console.error.calls.argsFor(0)[0]).toContain(
-          'Warning: Text content did not match.',
-        );
-      });
-
-      it('should render w/ no markup to full document', () => {
-        spyOn(console, 'error');
-        var testDocument = getTestDocument();
-
-        class Component extends React.Component {
-          render() {
-            return (
-              <html>
-                <head>
-                  <title>Hello World</title>
-                </head>
-                <body>
-                  {this.props.text}
-                </body>
-              </html>
-            );
-          }
+      class Component extends React.Component {
+        render() {
+          return (
+            <html>
+              <head>
+                <title>Hello World</title>
+              </head>
+              <body>
+                {this.props.text}
+              </body>
+            </html>
+          );
         }
+      }
 
-        ReactDOM.hydrate(<Component text="Hello world" />, testDocument);
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-        expectDev(console.error.calls.count()).toBe(1);
-        expectDev(console.error.calls.argsFor(0)[0]).toContain(
-          // getTestDocument() has an extra <meta> that we didn't render.
-          'Did not expect server HTML to contain a <meta> in <head>.',
-        );
-      });
-
-      it('supports findDOMNode on full-page components', () => {
-        var tree = (
-          <html>
-            <head>
-              <title>Hello World</title>
-            </head>
-            <body>
-              Hello world
-            </body>
-          </html>
-        );
-
-        var markup = ReactDOMServer.renderToString(tree);
-        var testDocument = getTestDocument(markup);
-        var component = ReactDOM.hydrate(tree, testDocument);
-        expect(testDocument.body.innerHTML).toBe('Hello world');
-        expect(ReactDOM.findDOMNode(component).tagName).toBe('HTML');
-      });
+      ReactDOM.hydrate(<Component text="Hello world" />, testDocument);
+      expect(testDocument.body.innerHTML).toBe('Hello world');
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(console.error.calls.argsFor(0)[0]).toContain(
+        // getTestDocument() has an extra <meta> that we didn't render.
+        'Did not expect server HTML to contain a <meta> in <head>.',
+      );
     });
-  }
+
+    it('supports findDOMNode on full-page components', () => {
+      var tree = (
+        <html>
+          <head>
+            <title>Hello World</title>
+          </head>
+          <body>
+            Hello world
+          </body>
+        </html>
+      );
+
+      var markup = ReactDOMServer.renderToString(tree);
+      var testDocument = getTestDocument(markup);
+      var component = ReactDOM.hydrate(tree, testDocument);
+      expect(testDocument.body.innerHTML).toBe('Hello world');
+      expect(ReactDOM.findDOMNode(component).tagName).toBe('HTML');
+    });
+  });
 });
diff --git a/src/renderers/dom/shared/__tests__/ReactServerRendering-test.js b/src/renderers/dom/shared/__tests__/ReactServerRendering-test.js
index cb3046b5e43..3ffb47787d4 100644
--- a/src/renderers/dom/shared/__tests__/ReactServerRendering-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactServerRendering-test.js
@@ -15,15 +15,10 @@ var ExecutionEnvironment;
 var React;
 var ReactDOM;
 var ReactDOMServer;
-var ReactMarkupChecksum;
-var ReactReconcileTransaction;
 var ReactTestUtils;
 var PropTypes;
 var ReactFeatureFlags;
 
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-
-var ID_ATTRIBUTE_NAME;
 var ROOT_ATTRIBUTE_NAME;
 
 describe('ReactDOMServer', () => {
@@ -32,8 +27,6 @@ describe('ReactDOMServer', () => {
     React = require('react');
     ReactDOM = require('react-dom');
     ReactTestUtils = require('react-dom/test-utils');
-    ReactMarkupChecksum = require('ReactMarkupChecksum');
-    ReactReconcileTransaction = require('ReactReconcileTransaction');
     PropTypes = require('prop-types');
 
     ReactFeatureFlags = require('ReactFeatureFlags');
@@ -44,7 +37,6 @@ describe('ReactDOMServer', () => {
     ReactDOMServer = require('react-dom/server');
 
     var DOMProperty = require('DOMProperty');
-    ID_ATTRIBUTE_NAME = DOMProperty.ID_ATTRIBUTE_NAME;
     ROOT_ATTRIBUTE_NAME = DOMProperty.ROOT_ATTRIBUTE_NAME;
   });
 
@@ -53,16 +45,7 @@ describe('ReactDOMServer', () => {
       var response = ReactDOMServer.renderToString(<span>hello world</span>);
       expect(response).toMatch(
         new RegExp(
-          '<span ' +
-            ROOT_ATTRIBUTE_NAME +
-            '=""' +
-            (ReactDOMFeatureFlags.useFiber
-              ? ''
-              : ' ' + ID_ATTRIBUTE_NAME + '="[^"]*"') +
-            (ReactDOMFeatureFlags.useFiber
-              ? ''
-              : ' ' + ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+"') +
-            '>hello world</span>',
+          '<span ' + ROOT_ATTRIBUTE_NAME + '=""' + '>hello world</span>',
         ),
       );
     });
@@ -70,18 +53,7 @@ describe('ReactDOMServer', () => {
     it('should generate simple markup for self-closing tags', () => {
       var response = ReactDOMServer.renderToString(<img />);
       expect(response).toMatch(
-        new RegExp(
-          '<img ' +
-            ROOT_ATTRIBUTE_NAME +
-            '=""' +
-            (ReactDOMFeatureFlags.useFiber
-              ? ''
-              : ' ' + ID_ATTRIBUTE_NAME + '="[^"]*"') +
-            (ReactDOMFeatureFlags.useFiber
-              ? ''
-              : ' ' + ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+"') +
-            '/>',
-        ),
+        new RegExp('<img ' + ROOT_ATTRIBUTE_NAME + '=""' + '/>'),
       );
     });
 
@@ -89,16 +61,7 @@ describe('ReactDOMServer', () => {
       var response = ReactDOMServer.renderToString(<img data-attr=">" />);
       expect(response).toMatch(
         new RegExp(
-          '<img data-attr="&gt;" ' +
-            ROOT_ATTRIBUTE_NAME +
-            '=""' +
-            (ReactDOMFeatureFlags.useFiber
-              ? ''
-              : ' ' + ID_ATTRIBUTE_NAME + '="[^"]*"') +
-            (ReactDOMFeatureFlags.useFiber
-              ? ''
-              : ' ' + ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+"') +
-            '/>',
+          '<img data-attr="&gt;" ' + ROOT_ATTRIBUTE_NAME + '=""' + '/>',
         ),
       );
     });
@@ -111,11 +74,7 @@ describe('ReactDOMServer', () => {
       }
 
       var response = ReactDOMServer.renderToString(<NullComponent />);
-      if (ReactDOMFeatureFlags.useFiber) {
-        expect(response).toBe('');
-      } else {
-        expect(response).toBe('<!-- react-empty: 1 -->');
-      }
+      expect(response).toBe('');
     });
 
     // TODO: Test that listeners are not registered onto any document/container.
@@ -139,22 +98,10 @@ describe('ReactDOMServer', () => {
           '<div ' +
             ROOT_ATTRIBUTE_NAME +
             '=""' +
-            (ReactDOMFeatureFlags.useFiber
-              ? ''
-              : ' ' + ID_ATTRIBUTE_NAME + '="[^"]*"') +
-            (ReactDOMFeatureFlags.useFiber
-              ? ''
-              : ' ' + ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+"') +
             '>' +
             '<span' +
-            (ReactDOMFeatureFlags.useFiber
-              ? ''
-              : ' ' + ID_ATTRIBUTE_NAME + '="[^"]*"') +
             '>' +
-            (ReactDOMFeatureFlags.useFiber
-              ? 'My name is <!-- -->child'
-              : '<!-- react-text: [0-9]+ -->My name is <!-- /react-text -->' +
-                  '<!-- react-text: [0-9]+ -->child<!-- /react-text -->') +
+            'My name is <!-- -->child' +
             '</span>' +
             '</div>',
         ),
@@ -213,17 +160,8 @@ describe('ReactDOMServer', () => {
             '<span ' +
               ROOT_ATTRIBUTE_NAME +
               '=""' +
-              (ReactDOMFeatureFlags.useFiber
-                ? ''
-                : ' ' + ID_ATTRIBUTE_NAME + '="[^"]*"') +
-              (ReactDOMFeatureFlags.useFiber
-                ? ''
-                : ' ' + ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+"') +
               '>' +
-              (ReactDOMFeatureFlags.useFiber
-                ? 'Component name: <!-- -->TestComponent'
-                : '<!-- react-text: [0-9]+ -->Component name: <!-- /react-text -->' +
-                    '<!-- react-text: [0-9]+ -->TestComponent<!-- /react-text -->') +
+              'Component name: <!-- -->TestComponent' +
               '</span>',
           ),
         );
@@ -298,24 +236,14 @@ describe('ReactDOMServer', () => {
 
       var instance = ReactDOM.render(<TestComponent name="x" />, element);
       expect(mountCount).toEqual(3);
-      if (ReactDOMFeatureFlags.useFiber) {
-        expectDev(console.warn.calls.count()).toBe(1);
-        expectDev(console.warn.calls.argsFor(0)[0]).toContain(
-          'render(): Calling ReactDOM.render() to hydrate server-rendered markup ' +
-            'will stop working in React v17. Replace the ReactDOM.render() call ' +
-            'with ReactDOM.hydrate() if you want React to attach to the server HTML.',
-        );
-      } else {
-        expectDev(console.warn.calls.count()).toBe(0);
-      }
+      expectDev(console.warn.calls.count()).toBe(1);
+      expectDev(console.warn.calls.argsFor(0)[0]).toContain(
+        'render(): Calling ReactDOM.render() to hydrate server-rendered markup ' +
+          'will stop working in React v17. Replace the ReactDOM.render() call ' +
+          'with ReactDOM.hydrate() if you want React to attach to the server HTML.',
+      );
       console.warn.calls.reset();
-
-      var expectedMarkup = lastMarkup;
-      if (ReactDOMFeatureFlags.useFiber) {
-        var reactComments = /<!-- \/?react-text(: \d+)? -->/g;
-        expectedMarkup = expectedMarkup.replace(reactComments, '');
-      }
-      expect(element.innerHTML).toBe(expectedMarkup);
+      expect(element.innerHTML).toBe(lastMarkup);
 
       // Ensure the events system works after mount into server markup
       expect(numClicks).toEqual(0);
@@ -331,18 +259,9 @@ describe('ReactDOMServer', () => {
       instance = ReactDOM.render(<TestComponent name="y" />, element);
       expect(mountCount).toEqual(4);
       expectDev(console.error.calls.count()).toBe(1);
-      if (ReactDOMFeatureFlags.useFiber) {
-        expectDev(console.error.calls.argsFor(0)[0]).toContain(
-          'Text content did not match. Server: "x" Client: "y"',
-        );
-      } else {
-        expectDev(console.error.calls.argsFor(0)[0]).toContain(
-          '(client) -- react-text: 3 -->y<!-- /react-text --',
-        );
-        expectDev(console.error.calls.argsFor(0)[0]).toContain(
-          '(server) -- react-text: 3 -->x<!-- /react-text --',
-        );
-      }
+      expectDev(console.error.calls.argsFor(0)[0]).toContain(
+        'Text content did not match. Server: "x" Client: "y"',
+      );
       console.error.calls.reset();
       expect(element.innerHTML.length > 0).toBe(true);
       expect(element.innerHTML).not.toEqual(lastMarkup);
@@ -355,104 +274,94 @@ describe('ReactDOMServer', () => {
       expectDev(console.error.calls.count()).toBe(0);
     });
 
-    if (ReactDOMFeatureFlags.useFiber) {
-      it('should have the correct mounting behavior (new hydrate API)', () => {
-        spyOn(console, 'error');
-        // This test is testing client-side behavior.
-        ExecutionEnvironment.canUseDOM = true;
+    it('should have the correct mounting behavior (new hydrate API)', () => {
+      spyOn(console, 'error');
+      // This test is testing client-side behavior.
+      ExecutionEnvironment.canUseDOM = true;
 
-        var mountCount = 0;
-        var numClicks = 0;
+      var mountCount = 0;
+      var numClicks = 0;
 
-        class TestComponent extends React.Component {
-          componentDidMount() {
-            mountCount++;
-          }
+      class TestComponent extends React.Component {
+        componentDidMount() {
+          mountCount++;
+        }
 
-          click = () => {
-            numClicks++;
-          };
+        click = () => {
+          numClicks++;
+        };
 
-          render() {
-            return (
-              <span ref="span" onClick={this.click}>
-                Name: {this.props.name}
-              </span>
-            );
-          }
+        render() {
+          return (
+            <span ref="span" onClick={this.click}>
+              Name: {this.props.name}
+            </span>
+          );
         }
+      }
 
-        var element = document.createElement('div');
-        ReactDOM.render(<TestComponent />, element);
-
-        var lastMarkup = element.innerHTML;
-
-        // Exercise the update path. Markup should not change,
-        // but some lifecycle methods should be run again.
-        ReactDOM.render(<TestComponent name="x" />, element);
-        expect(mountCount).toEqual(1);
-
-        // Unmount and remount. We should get another mount event and
-        // we should get different markup, as the IDs are unique each time.
-        ReactDOM.unmountComponentAtNode(element);
-        expect(element.innerHTML).toEqual('');
-        ReactDOM.render(<TestComponent name="x" />, element);
-        expect(mountCount).toEqual(2);
-        expect(element.innerHTML).not.toEqual(lastMarkup);
-
-        // Now kill the node and render it on top of server-rendered markup, as if
-        // we used server rendering. We should mount again, but the markup should
-        // be unchanged. We will append a sentinel at the end of innerHTML to be
-        // sure that innerHTML was not changed.
-        ReactDOM.unmountComponentAtNode(element);
-        expect(element.innerHTML).toEqual('');
-
-        ExecutionEnvironment.canUseDOM = false;
-        lastMarkup = ReactDOMServer.renderToString(<TestComponent name="x" />);
-        ExecutionEnvironment.canUseDOM = true;
-        element.innerHTML = lastMarkup;
-
-        var instance = ReactDOM.hydrate(<TestComponent name="x" />, element);
-        expect(mountCount).toEqual(3);
-
-        var expectedMarkup = lastMarkup;
-        if (ReactDOMFeatureFlags.useFiber) {
-          var reactComments = /<!-- \/?react-text(: \d+)? -->/g;
-          expectedMarkup = expectedMarkup.replace(reactComments, '');
-        }
-        expect(element.innerHTML).toBe(expectedMarkup);
-
-        // Ensure the events system works after mount into server markup
-        expect(numClicks).toEqual(0);
-        ReactTestUtils.Simulate.click(ReactDOM.findDOMNode(instance.refs.span));
-        expect(numClicks).toEqual(1);
-
-        ReactDOM.unmountComponentAtNode(element);
-        expect(element.innerHTML).toEqual('');
-
-        // Now simulate a situation where the app is not idempotent. React should
-        // warn but do the right thing.
-        element.innerHTML = lastMarkup;
-        instance = ReactDOM.hydrate(<TestComponent name="y" />, element);
-        expect(mountCount).toEqual(4);
-        expectDev(console.error.calls.count()).toBe(1);
-        expect(element.innerHTML.length > 0).toBe(true);
-        expect(element.innerHTML).not.toEqual(lastMarkup);
-
-        // Ensure the events system works after markup mismatch.
-        expect(numClicks).toEqual(1);
-        ReactTestUtils.Simulate.click(ReactDOM.findDOMNode(instance.refs.span));
-        expect(numClicks).toEqual(2);
-      });
-    }
+      var element = document.createElement('div');
+      ReactDOM.render(<TestComponent />, element);
+
+      var lastMarkup = element.innerHTML;
+
+      // Exercise the update path. Markup should not change,
+      // but some lifecycle methods should be run again.
+      ReactDOM.render(<TestComponent name="x" />, element);
+      expect(mountCount).toEqual(1);
+
+      // Unmount and remount. We should get another mount event and
+      // we should get different markup, as the IDs are unique each time.
+      ReactDOM.unmountComponentAtNode(element);
+      expect(element.innerHTML).toEqual('');
+      ReactDOM.render(<TestComponent name="x" />, element);
+      expect(mountCount).toEqual(2);
+      expect(element.innerHTML).not.toEqual(lastMarkup);
+
+      // Now kill the node and render it on top of server-rendered markup, as if
+      // we used server rendering. We should mount again, but the markup should
+      // be unchanged. We will append a sentinel at the end of innerHTML to be
+      // sure that innerHTML was not changed.
+      ReactDOM.unmountComponentAtNode(element);
+      expect(element.innerHTML).toEqual('');
+
+      ExecutionEnvironment.canUseDOM = false;
+      lastMarkup = ReactDOMServer.renderToString(<TestComponent name="x" />);
+      ExecutionEnvironment.canUseDOM = true;
+      element.innerHTML = lastMarkup;
+
+      var instance = ReactDOM.hydrate(<TestComponent name="x" />, element);
+      expect(mountCount).toEqual(3);
+      expect(element.innerHTML).toBe(lastMarkup);
+
+      // Ensure the events system works after mount into server markup
+      expect(numClicks).toEqual(0);
+      ReactTestUtils.Simulate.click(ReactDOM.findDOMNode(instance.refs.span));
+      expect(numClicks).toEqual(1);
+
+      ReactDOM.unmountComponentAtNode(element);
+      expect(element.innerHTML).toEqual('');
+
+      // Now simulate a situation where the app is not idempotent. React should
+      // warn but do the right thing.
+      element.innerHTML = lastMarkup;
+      instance = ReactDOM.hydrate(<TestComponent name="y" />, element);
+      expect(mountCount).toEqual(4);
+      expectDev(console.error.calls.count()).toBe(1);
+      expect(element.innerHTML.length > 0).toBe(true);
+      expect(element.innerHTML).not.toEqual(lastMarkup);
+
+      // Ensure the events system works after markup mismatch.
+      expect(numClicks).toEqual(1);
+      ReactTestUtils.Simulate.click(ReactDOM.findDOMNode(instance.refs.span));
+      expect(numClicks).toEqual(2);
+    });
 
     it('should throw with silly args', () => {
       expect(
         ReactDOMServer.renderToString.bind(ReactDOMServer, {x: 123}),
       ).toThrowError(
-        ReactDOMFeatureFlags.useFiber
-          ? 'Objects are not valid as a React child (found: object with keys {x})'
-          : 'renderToString(): Invalid component element.',
+        'Objects are not valid as a React child (found: object with keys {x})',
       );
     });
   });
@@ -566,9 +475,7 @@ describe('ReactDOMServer', () => {
       expect(
         ReactDOMServer.renderToStaticMarkup.bind(ReactDOMServer, {x: 123}),
       ).toThrowError(
-        ReactDOMFeatureFlags.useFiber
-          ? 'Objects are not valid as a React child (found: object with keys {x})'
-          : 'renderToStaticMarkup(): Invalid component element.',
+        'Objects are not valid as a React child (found: object with keys {x})',
       );
     });
 
@@ -582,11 +489,6 @@ describe('ReactDOMServer', () => {
           return <div>{this.state.text}</div>;
         }
       }
-
-      ReactReconcileTransaction.prototype.perform = function() {
-        // We shouldn't ever be calling this on the server
-        throw new Error('Browser reconcile transaction should not be used');
-      };
       var markup = ReactDOMServer.renderToString(<Component />);
       expect(markup).toContain('hello, world');
     });
@@ -606,11 +508,6 @@ describe('ReactDOMServer', () => {
           return <div>{this.state.text}</div>;
         }
       }
-
-      ReactReconcileTransaction.prototype.perform = function() {
-        // We shouldn't ever be calling this on the server
-        throw new Error('Browser reconcile transaction should not be used');
-      };
       var markup = ReactDOMServer.renderToString(<Component />);
       expect(markup).toContain('hello, world');
     });
diff --git a/src/renderers/dom/shared/__tests__/ReactServerRenderingBrowser-test.js b/src/renderers/dom/shared/__tests__/ReactServerRenderingBrowser-test.js
index fa136444a93..fc658fa28e3 100644
--- a/src/renderers/dom/shared/__tests__/ReactServerRenderingBrowser-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactServerRenderingBrowser-test.js
@@ -15,8 +15,6 @@ var React;
 var ReactDOMServer;
 var ReactDOMServerBrowser;
 
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-
 describe('ReactServerRenderingBrowser', () => {
   beforeEach(() => {
     jest.resetModules();
@@ -55,18 +53,16 @@ describe('ReactServerRenderingBrowser', () => {
     );
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    it('throws meaningfully for server-only APIs', () => {
-      expect(() => ReactDOMServerBrowser.renderToNodeStream(<div />)).toThrow(
-        'ReactDOMServer.renderToNodeStream(): The streaming API is not available ' +
-          'in the browser. Use ReactDOMServer.renderToString() instead.',
-      );
-      expect(() =>
-        ReactDOMServerBrowser.renderToStaticNodeStream(<div />),
-      ).toThrow(
-        'ReactDOMServer.renderToStaticNodeStream(): The streaming API is not available ' +
-          'in the browser. Use ReactDOMServer.renderToStaticMarkup() instead.',
-      );
-    });
-  }
+  it('throws meaningfully for server-only APIs', () => {
+    expect(() => ReactDOMServerBrowser.renderToNodeStream(<div />)).toThrow(
+      'ReactDOMServer.renderToNodeStream(): The streaming API is not available ' +
+        'in the browser. Use ReactDOMServer.renderToString() instead.',
+    );
+    expect(() =>
+      ReactDOMServerBrowser.renderToStaticNodeStream(<div />),
+    ).toThrow(
+      'ReactDOMServer.renderToStaticNodeStream(): The streaming API is not available ' +
+        'in the browser. Use ReactDOMServer.renderToStaticMarkup() instead.',
+    );
+  });
 });
diff --git a/src/renderers/dom/shared/__tests__/renderSubtreeIntoContainer-test.js b/src/renderers/dom/shared/__tests__/renderSubtreeIntoContainer-test.js
index cca63bffa77..d7f33135be8 100644
--- a/src/renderers/dom/shared/__tests__/renderSubtreeIntoContainer-test.js
+++ b/src/renderers/dom/shared/__tests__/renderSubtreeIntoContainer-test.js
@@ -14,7 +14,6 @@
 var React = require('react');
 var PropTypes = require('prop-types');
 var ReactDOM = require('react-dom');
-var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 var ReactTestUtils = require('react-dom/test-utils');
 var renderSubtreeIntoContainer = require('react-dom')
   .unstable_renderSubtreeIntoContainer;
@@ -301,26 +300,24 @@ describe('renderSubtreeIntoContainer', () => {
     expect(portal2.textContent).toBe('foo');
   });
 
-  if (ReactDOMFeatureFlags.useFiber) {
-    it('fails gracefully when mixing React 15 and 16', () => {
-      class C extends React.Component {
-        render() {
-          return <div />;
-        }
-      }
-      const c = ReactDOM.render(<C />, document.createElement('div'));
-      // React 15 calls this:
-      // https://github.com/facebook/react/blob/77b71fc3c4/src/renderers/dom/client/ReactMount.js#L478-L479
-      expect(() => {
-        c._reactInternalInstance._processChildContext({});
-      }).toThrow(
-        '_processChildContext is not available in React 16+. This likely ' +
-          'means you have multiple copies of React and are attempting to nest ' +
-          'a React 15 tree inside a React 16 tree using ' +
-          "unstable_renderSubtreeIntoContainer, which isn't supported. Try to " +
-          'make sure you have only one copy of React (and ideally, switch to ' +
-          'ReactDOM.unstable_createPortal).',
-      );
-    });
-  }
+  it('fails gracefully when mixing React 15 and 16', () => {
+    class C extends React.Component {
+      render() {
+        return <div />;
+      }
+    }
+    const c = ReactDOM.render(<C />, document.createElement('div'));
+    // React 15 calls this:
+    // https://github.com/facebook/react/blob/77b71fc3c4/src/renderers/dom/client/ReactMount.js#L478-L479
+    expect(() => {
+      c._reactInternalInstance._processChildContext({});
+    }).toThrow(
+      '_processChildContext is not available in React 16+. This likely ' +
+        'means you have multiple copies of React and are attempting to nest ' +
+        'a React 15 tree inside a React 16 tree using ' +
+        "unstable_renderSubtreeIntoContainer, which isn't supported. Try to " +
+        'make sure you have only one copy of React (and ideally, switch to ' +
+        'ReactDOM.unstable_createPortal).',
+    );
+  });
 });
diff --git a/src/renderers/dom/shared/checkReact.js b/src/renderers/dom/shared/checkReact.js
index a8d73cd5bc8..2e539768657 100644
--- a/src/renderers/dom/shared/checkReact.js
+++ b/src/renderers/dom/shared/checkReact.js
@@ -10,8 +10,8 @@
  * @flow
  */
 
-var React = require('react');
-var invariant = require('fbjs/lib/invariant');
+import React from 'react';
+import invariant from 'fbjs/lib/invariant';
 
 invariant(
   React,
diff --git a/src/renderers/dom/shared/createMicrosoftUnsafeLocalFunction.js b/src/renderers/dom/shared/createMicrosoftUnsafeLocalFunction.js
index 834ad9849ba..ec3da6f9d27 100644
--- a/src/renderers/dom/shared/createMicrosoftUnsafeLocalFunction.js
+++ b/src/renderers/dom/shared/createMicrosoftUnsafeLocalFunction.js
@@ -16,7 +16,7 @@
 /**
  * Create a function which has 'unsafe' privileges (required by windows8 apps)
  */
-var createMicrosoftUnsafeLocalFunction = function(func) {
+export default function createMicrosoftUnsafeLocalFunction(func) {
   if (typeof MSApp !== 'undefined' && MSApp.execUnsafeLocalFunction) {
     return function(arg0, arg1, arg2, arg3) {
       MSApp.execUnsafeLocalFunction(function() {
@@ -26,6 +26,4 @@ var createMicrosoftUnsafeLocalFunction = function(func) {
   } else {
     return func;
   }
-};
-
-module.exports = createMicrosoftUnsafeLocalFunction;
+}
diff --git a/src/renderers/dom/shared/dangerousStyleValue.js b/src/renderers/dom/shared/dangerousStyleValue.js
index 033fa2dbbb5..b267433ad7f 100644
--- a/src/renderers/dom/shared/dangerousStyleValue.js
+++ b/src/renderers/dom/shared/dangerousStyleValue.js
@@ -11,9 +11,7 @@
 
 'use strict';
 
-var CSSProperty = require('CSSProperty');
-
-var isUnitlessNumber = CSSProperty.isUnitlessNumber;
+import {isUnitlessNumber} from 'CSSProperty';
 
 /**
  * Convert a value into the proper css writable value. The style name `name`
@@ -24,7 +22,7 @@ var isUnitlessNumber = CSSProperty.isUnitlessNumber;
  * @param {*} value CSS property value such as `10px`.
  * @return {string} Normalized style value with dimensions applied.
  */
-function dangerousStyleValue(name, value, isCustomProperty) {
+export default function dangerousStyleValue(name, value, isCustomProperty) {
   // Note that we've removed escapeTextForBrowser() calls here since the
   // whole string will be escaped when the attribute is injected into
   // the markup. If you provide unsafe user data here they can inject
@@ -51,5 +49,3 @@ function dangerousStyleValue(name, value, isCustomProperty) {
 
   return ('' + value).trim();
 }
-
-module.exports = dangerousStyleValue;
diff --git a/src/renderers/dom/shared/escapeTextContentForBrowser.js b/src/renderers/dom/shared/escapeTextContentForBrowser.js
index 9a7a2f10dbf..72649be1633 100644
--- a/src/renderers/dom/shared/escapeTextContentForBrowser.js
+++ b/src/renderers/dom/shared/escapeTextContentForBrowser.js
@@ -104,7 +104,7 @@ function escapeHtml(string) {
  * @param {*} text Text value to escape.
  * @return {string} An escaped string.
  */
-function escapeTextContentForBrowser(text) {
+export default function escapeTextContentForBrowser(text) {
   if (typeof text === 'boolean' || typeof text === 'number') {
     // this shortcircuit helps perf for types that we know will never have
     // special characters, especially given that this function is used often
@@ -113,5 +113,3 @@ function escapeTextContentForBrowser(text) {
   }
   return escapeHtml(text);
 }
-
-module.exports = escapeTextContentForBrowser;
diff --git a/src/renderers/dom/shared/eventPlugins/BeforeInputEventPlugin.js b/src/renderers/dom/shared/eventPlugins/BeforeInputEventPlugin.js
index 09575109421..5a534dd80ad 100644
--- a/src/renderers/dom/shared/eventPlugins/BeforeInputEventPlugin.js
+++ b/src/renderers/dom/shared/eventPlugins/BeforeInputEventPlugin.js
@@ -11,11 +11,15 @@
 
 'use strict';
 
-var EventPropagators = require('EventPropagators');
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
-var FallbackCompositionState = require('FallbackCompositionState');
-var SyntheticCompositionEvent = require('SyntheticCompositionEvent');
-var SyntheticInputEvent = require('SyntheticInputEvent');
+import {accumulateTwoPhaseDispatches} from 'EventPropagators';
+import ExecutionEnvironment from 'fbjs/lib/ExecutionEnvironment';
+import {
+  initialize as initializeFallbackCompositionState,
+  getData as getFallbackCompositionStateData,
+  reset as resetFallbackCompositionState,
+} from 'FallbackCompositionState';
+import SyntheticCompositionEvent from 'SyntheticCompositionEvent';
+import SyntheticInputEvent from 'SyntheticInputEvent';
 
 import type {TopLevelTypes} from 'BrowserEventConstants';
 
@@ -242,10 +246,10 @@ function extractCompositionEvent(
     // The current composition is stored statically and must not be
     // overwritten while composition continues.
     if (!isComposing && eventType === eventTypes.compositionStart) {
-      isComposing = FallbackCompositionState.initialize(nativeEventTarget);
+      isComposing = initializeFallbackCompositionState(nativeEventTarget);
     } else if (eventType === eventTypes.compositionEnd) {
       if (isComposing) {
-        fallbackData = FallbackCompositionState.getData();
+        fallbackData = getFallbackCompositionStateData();
       }
     }
   }
@@ -268,7 +272,7 @@ function extractCompositionEvent(
     }
   }
 
-  EventPropagators.accumulateTwoPhaseDispatches(event);
+  accumulateTwoPhaseDispatches(event);
   return event;
 }
 
@@ -342,8 +346,8 @@ function getFallbackBeforeInputChars(topLevelType: TopLevelTypes, nativeEvent) {
       (!canUseCompositionEvent &&
         isFallbackCompositionEnd(topLevelType, nativeEvent))
     ) {
-      var chars = FallbackCompositionState.getData();
-      FallbackCompositionState.reset();
+      var chars = getFallbackCompositionStateData();
+      resetFallbackCompositionState();
       isComposing = false;
       return chars;
     }
@@ -427,7 +431,7 @@ function extractBeforeInputEvent(
   );
 
   event.data = chars;
-  EventPropagators.accumulateTwoPhaseDispatches(event);
+  accumulateTwoPhaseDispatches(event);
   return event;
 }
 
@@ -475,4 +479,4 @@ var BeforeInputEventPlugin = {
   },
 };
 
-module.exports = BeforeInputEventPlugin;
+export default BeforeInputEventPlugin;
diff --git a/src/renderers/dom/shared/eventPlugins/ChangeEventPlugin.js b/src/renderers/dom/shared/eventPlugins/ChangeEventPlugin.js
index 387ec571ec9..9cd6e236c94 100644
--- a/src/renderers/dom/shared/eventPlugins/ChangeEventPlugin.js
+++ b/src/renderers/dom/shared/eventPlugins/ChangeEventPlugin.js
@@ -11,18 +11,18 @@
 
 'use strict';
 
-var EventPluginHub = require('EventPluginHub');
-var EventPropagators = require('EventPropagators');
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
-var ReactControlledComponent = require('ReactControlledComponent');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactGenericBatching = require('ReactGenericBatching');
-var SyntheticEvent = require('SyntheticEvent');
-
-var inputValueTracking = require('inputValueTracking');
-var getEventTarget = require('getEventTarget');
-var isEventSupported = require('isEventSupported');
-var isTextInputElement = require('isTextInputElement');
+import {enqueueEvents, processEventQueue} from 'EventPluginHub';
+import {accumulateTwoPhaseDispatches} from 'EventPropagators';
+import ExecutionEnvironment from 'fbjs/lib/ExecutionEnvironment';
+import {enqueueStateRestore} from 'ReactControlledComponent';
+import {getNodeFromInstance} from 'ReactDOMComponentTree';
+import {batchedUpdates} from 'ReactGenericBatching';
+import SyntheticEvent from 'SyntheticEvent';
+
+import {updateValueIfChanged} from 'inputValueTracking';
+import getEventTarget from 'getEventTarget';
+import isEventSupported from 'isEventSupported';
+import isTextInputElement from 'isTextInputElement';
 
 var eventTypes = {
   change: {
@@ -52,8 +52,8 @@ function createAndAccumulateChangeEvent(inst, nativeEvent, target) {
   );
   event.type = 'change';
   // Flag this event loop as needing state restore.
-  ReactControlledComponent.enqueueStateRestore(target);
-  EventPropagators.accumulateTwoPhaseDispatches(event);
+  enqueueStateRestore(target);
+  accumulateTwoPhaseDispatches(event);
   return event;
 }
 /**
@@ -90,17 +90,17 @@ function manualDispatchChangeEvent(nativeEvent) {
   // components don't work properly in conjunction with event bubbling because
   // the component is rerendered and the value reverted before all the event
   // handlers can run. See https://github.com/facebook/react/issues/708.
-  ReactGenericBatching.batchedUpdates(runEventInBatch, event);
+  batchedUpdates(runEventInBatch, event);
 }
 
 function runEventInBatch(event) {
-  EventPluginHub.enqueueEvents(event);
-  EventPluginHub.processEventQueue(false);
+  enqueueEvents(event);
+  processEventQueue(false);
 }
 
 function getInstIfValueChanged(targetInst) {
-  const targetNode = ReactDOMComponentTree.getNodeFromInstance(targetInst);
-  if (inputValueTracking.updateValueIfChanged(targetNode)) {
+  const targetNode = getNodeFromInstance(targetInst);
+  if (updateValueIfChanged(targetNode)) {
     return targetInst;
   }
 }
@@ -268,9 +268,7 @@ var ChangeEventPlugin = {
     nativeEvent,
     nativeEventTarget,
   ) {
-    var targetNode = targetInst
-      ? ReactDOMComponentTree.getNodeFromInstance(targetInst)
-      : window;
+    var targetNode = targetInst ? getNodeFromInstance(targetInst) : window;
 
     var getTargetInstFunc, handleEventFunc;
     if (shouldUseChangeEvent(targetNode)) {
@@ -309,4 +307,4 @@ var ChangeEventPlugin = {
   },
 };
 
-module.exports = ChangeEventPlugin;
+export default ChangeEventPlugin;
diff --git a/src/renderers/dom/shared/eventPlugins/DOMEventPluginOrder.js b/src/renderers/dom/shared/eventPlugins/DOMEventPluginOrder.js
index 510ec07ad0b..4991281f749 100644
--- a/src/renderers/dom/shared/eventPlugins/DOMEventPluginOrder.js
+++ b/src/renderers/dom/shared/eventPlugins/DOMEventPluginOrder.js
@@ -30,4 +30,4 @@ var DOMEventPluginOrder = [
   'BeforeInputEventPlugin',
 ];
 
-module.exports = DOMEventPluginOrder;
+export default DOMEventPluginOrder;
diff --git a/src/renderers/dom/shared/eventPlugins/EnterLeaveEventPlugin.js b/src/renderers/dom/shared/eventPlugins/EnterLeaveEventPlugin.js
index fa9925f1448..6a149578a7d 100644
--- a/src/renderers/dom/shared/eventPlugins/EnterLeaveEventPlugin.js
+++ b/src/renderers/dom/shared/eventPlugins/EnterLeaveEventPlugin.js
@@ -11,9 +11,12 @@
 
 'use strict';
 
-var EventPropagators = require('EventPropagators');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var SyntheticMouseEvent = require('SyntheticMouseEvent');
+import {accumulateEnterLeaveDispatches} from 'EventPropagators';
+import {
+  getClosestInstanceFromNode,
+  getNodeFromInstance,
+} from 'ReactDOMComponentTree';
+import SyntheticMouseEvent from 'SyntheticMouseEvent';
 
 var eventTypes = {
   mouseEnter: {
@@ -72,9 +75,7 @@ var EnterLeaveEventPlugin = {
     if (topLevelType === 'topMouseOut') {
       from = targetInst;
       var related = nativeEvent.relatedTarget || nativeEvent.toElement;
-      to = related
-        ? ReactDOMComponentTree.getClosestInstanceFromNode(related)
-        : null;
+      to = related ? getClosestInstanceFromNode(related) : null;
     } else {
       // Moving to a node from outside the window.
       from = null;
@@ -86,12 +87,8 @@ var EnterLeaveEventPlugin = {
       return null;
     }
 
-    var fromNode = from == null
-      ? win
-      : ReactDOMComponentTree.getNodeFromInstance(from);
-    var toNode = to == null
-      ? win
-      : ReactDOMComponentTree.getNodeFromInstance(to);
+    var fromNode = from == null ? win : getNodeFromInstance(from);
+    var toNode = to == null ? win : getNodeFromInstance(to);
 
     var leave = SyntheticMouseEvent.getPooled(
       eventTypes.mouseLeave,
@@ -113,10 +110,10 @@ var EnterLeaveEventPlugin = {
     enter.target = toNode;
     enter.relatedTarget = fromNode;
 
-    EventPropagators.accumulateEnterLeaveDispatches(leave, enter, from, to);
+    accumulateEnterLeaveDispatches(leave, enter, from, to);
 
     return [leave, enter];
   },
 };
 
-module.exports = EnterLeaveEventPlugin;
+export default EnterLeaveEventPlugin;
diff --git a/src/renderers/dom/shared/eventPlugins/FallbackCompositionState.js b/src/renderers/dom/shared/eventPlugins/FallbackCompositionState.js
index 41028f88fe4..a35e96d6c8d 100644
--- a/src/renderers/dom/shared/eventPlugins/FallbackCompositionState.js
+++ b/src/renderers/dom/shared/eventPlugins/FallbackCompositionState.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var getTextContentAccessor = require('getTextContentAccessor');
+import getTextContentAccessor from 'getTextContentAccessor';
 
 /**
  * This helper object stores information about text content of a target node,
@@ -30,52 +30,48 @@ var compositionState = {
   _fallbackText: null,
 };
 
-var FallbackCompositionState = {
-  initialize(nativeEventTarget) {
-    compositionState._root = nativeEventTarget;
-    compositionState._startText = FallbackCompositionState.getText();
-    return true;
-  },
-  reset() {
-    compositionState._root = null;
-    compositionState._startText = null;
-    compositionState._fallbackText = null;
-  },
-  getData() {
-    if (compositionState._fallbackText) {
-      return compositionState._fallbackText;
-    }
-
-    var start;
-    var startValue = compositionState._startText;
-    var startLength = startValue.length;
-    var end;
-    var endValue = FallbackCompositionState.getText();
-    var endLength = endValue.length;
+export function initialize(nativeEventTarget) {
+  compositionState._root = nativeEventTarget;
+  compositionState._startText = getText();
+  return true;
+}
+export function reset() {
+  compositionState._root = null;
+  compositionState._startText = null;
+  compositionState._fallbackText = null;
+}
+export function getData() {
+  if (compositionState._fallbackText) {
+    return compositionState._fallbackText;
+  }
 
-    for (start = 0; start < startLength; start++) {
-      if (startValue[start] !== endValue[start]) {
-        break;
-      }
-    }
+  var start;
+  var startValue = compositionState._startText;
+  var startLength = startValue.length;
+  var end;
+  var endValue = getText();
+  var endLength = endValue.length;
 
-    var minEnd = startLength - start;
-    for (end = 1; end <= minEnd; end++) {
-      if (startValue[startLength - end] !== endValue[endLength - end]) {
-        break;
-      }
+  for (start = 0; start < startLength; start++) {
+    if (startValue[start] !== endValue[start]) {
+      break;
     }
+  }
 
-    var sliceTail = end > 1 ? 1 - end : undefined;
-    compositionState._fallbackText = endValue.slice(start, sliceTail);
-    return compositionState._fallbackText;
-  },
-  getText() {
-    if ('value' in compositionState._root) {
-      return compositionState._root.value;
+  var minEnd = startLength - start;
+  for (end = 1; end <= minEnd; end++) {
+    if (startValue[startLength - end] !== endValue[endLength - end]) {
+      break;
     }
-    return compositionState._root[getTextContentAccessor()];
-  },
-};
+  }
 
-module.exports = FallbackCompositionState;
+  var sliceTail = end > 1 ? 1 - end : undefined;
+  compositionState._fallbackText = endValue.slice(start, sliceTail);
+  return compositionState._fallbackText;
+}
+export function getText() {
+  if ('value' in compositionState._root) {
+    return compositionState._root.value;
+  }
+  return compositionState._root[getTextContentAccessor()];
+}
diff --git a/src/renderers/dom/shared/eventPlugins/SelectEventPlugin.js b/src/renderers/dom/shared/eventPlugins/SelectEventPlugin.js
index 6e1f214036d..93a9499462d 100644
--- a/src/renderers/dom/shared/eventPlugins/SelectEventPlugin.js
+++ b/src/renderers/dom/shared/eventPlugins/SelectEventPlugin.js
@@ -11,17 +11,17 @@
 
 'use strict';
 
-var EventPropagators = require('EventPropagators');
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
-var ReactBrowserEventEmitter = require('ReactBrowserEventEmitter');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactInputSelection = require('ReactInputSelection');
-var SyntheticEvent = require('SyntheticEvent');
-var {DOCUMENT_NODE} = require('HTMLNodeType');
-
-var getActiveElement = require('fbjs/lib/getActiveElement');
-var isTextInputElement = require('isTextInputElement');
-var shallowEqual = require('fbjs/lib/shallowEqual');
+import {accumulateTwoPhaseDispatches} from 'EventPropagators';
+import ExecutionEnvironment from 'fbjs/lib/ExecutionEnvironment';
+import {isListeningToAllDependencies} from 'ReactBrowserEventEmitter';
+import {getNodeFromInstance} from 'ReactDOMComponentTree';
+import {hasSelectionCapabilities} from 'ReactInputSelection';
+import SyntheticEvent from 'SyntheticEvent';
+import {DOCUMENT_NODE} from 'HTMLNodeType';
+
+import getActiveElement from 'fbjs/lib/getActiveElement';
+import isTextInputElement from 'isTextInputElement';
+import shallowEqual from 'fbjs/lib/shallowEqual';
 
 var skipSelectionChangeEvent =
   ExecutionEnvironment.canUseDOM &&
@@ -52,11 +52,6 @@ var activeElementInst = null;
 var lastSelection = null;
 var mouseDown = false;
 
-// Track whether all listeners exists for this plugin. If none exist, we do
-// not extract events. See #3639.
-var isListeningToAllDependencies =
-  ReactBrowserEventEmitter.isListeningToAllDependencies;
-
 /**
  * Get an object which is a unique representation of the current selection.
  *
@@ -67,10 +62,7 @@ var isListeningToAllDependencies =
  * @return {object}
  */
 function getSelection(node) {
-  if (
-    'selectionStart' in node &&
-    ReactInputSelection.hasSelectionCapabilities(node)
-  ) {
+  if ('selectionStart' in node && hasSelectionCapabilities(node)) {
     return {
       start: node.selectionStart,
       end: node.selectionEnd,
@@ -120,7 +112,7 @@ function constructSelectEvent(nativeEvent, nativeEventTarget) {
     syntheticEvent.type = 'select';
     syntheticEvent.target = activeElement;
 
-    EventPropagators.accumulateTwoPhaseDispatches(syntheticEvent);
+    accumulateTwoPhaseDispatches(syntheticEvent);
 
     return syntheticEvent;
   }
@@ -156,13 +148,13 @@ var SelectEventPlugin = {
       : nativeEventTarget.nodeType === DOCUMENT_NODE
           ? nativeEventTarget
           : nativeEventTarget.ownerDocument;
+    // Track whether all listeners exists for this plugin. If none exist, we do
+    // not extract events. See #3639.
     if (!doc || !isListeningToAllDependencies('onSelect', doc)) {
       return null;
     }
 
-    var targetNode = targetInst
-      ? ReactDOMComponentTree.getNodeFromInstance(targetInst)
-      : window;
+    var targetNode = targetInst ? getNodeFromInstance(targetInst) : window;
 
     switch (topLevelType) {
       // Track the input node that has focus.
@@ -213,4 +205,4 @@ var SelectEventPlugin = {
   },
 };
 
-module.exports = SelectEventPlugin;
+export default SelectEventPlugin;
diff --git a/src/renderers/dom/shared/eventPlugins/SimpleEventPlugin.js b/src/renderers/dom/shared/eventPlugins/SimpleEventPlugin.js
index 7acdeaca06c..6c5b267dbdd 100644
--- a/src/renderers/dom/shared/eventPlugins/SimpleEventPlugin.js
+++ b/src/renderers/dom/shared/eventPlugins/SimpleEventPlugin.js
@@ -12,28 +12,28 @@
 
 'use strict';
 
-var EventPropagators = require('EventPropagators');
-var SyntheticAnimationEvent = require('SyntheticAnimationEvent');
-var SyntheticClipboardEvent = require('SyntheticClipboardEvent');
-var SyntheticEvent = require('SyntheticEvent');
-var SyntheticFocusEvent = require('SyntheticFocusEvent');
-var SyntheticKeyboardEvent = require('SyntheticKeyboardEvent');
-var SyntheticMouseEvent = require('SyntheticMouseEvent');
-var SyntheticDragEvent = require('SyntheticDragEvent');
-var SyntheticTouchEvent = require('SyntheticTouchEvent');
-var SyntheticTransitionEvent = require('SyntheticTransitionEvent');
-var SyntheticUIEvent = require('SyntheticUIEvent');
-var SyntheticWheelEvent = require('SyntheticWheelEvent');
+import {accumulateTwoPhaseDispatches} from 'EventPropagators';
+import SyntheticAnimationEvent from 'SyntheticAnimationEvent';
+import SyntheticClipboardEvent from 'SyntheticClipboardEvent';
+import SyntheticEvent from 'SyntheticEvent';
+import SyntheticFocusEvent from 'SyntheticFocusEvent';
+import SyntheticKeyboardEvent from 'SyntheticKeyboardEvent';
+import SyntheticMouseEvent from 'SyntheticMouseEvent';
+import SyntheticDragEvent from 'SyntheticDragEvent';
+import SyntheticTouchEvent from 'SyntheticTouchEvent';
+import SyntheticTransitionEvent from 'SyntheticTransitionEvent';
+import SyntheticUIEvent from 'SyntheticUIEvent';
+import SyntheticWheelEvent from 'SyntheticWheelEvent';
 
-var getEventCharCode = require('getEventCharCode');
-var invariant = require('fbjs/lib/invariant');
+import getEventCharCode from 'getEventCharCode';
+import invariant from 'fbjs/lib/invariant';
 
 import type {TopLevelTypes} from 'BrowserEventConstants';
 import type {
   DispatchConfig,
   ReactSyntheticEvent,
 } from 'ReactSyntheticEventType';
-import type {ReactInstance} from 'ReactInstanceType';
+import type {Fiber} from 'ReactFiber';
 import type {EventTypes, PluginModule} from 'PluginModuleType';
 
 /**
@@ -143,7 +143,7 @@ var SimpleEventPlugin: PluginModule<MouseEvent> = {
 
   extractEvents: function(
     topLevelType: TopLevelTypes,
-    targetInst: ReactInstance,
+    targetInst: Fiber,
     nativeEvent: MouseEvent,
     nativeEventTarget: EventTarget,
   ): null | ReactSyntheticEvent {
@@ -269,9 +269,9 @@ var SimpleEventPlugin: PluginModule<MouseEvent> = {
       nativeEvent,
       nativeEventTarget,
     );
-    EventPropagators.accumulateTwoPhaseDispatches(event);
+    accumulateTwoPhaseDispatches(event);
     return event;
   },
 };
 
-module.exports = SimpleEventPlugin;
+export default SimpleEventPlugin;
diff --git a/src/renderers/dom/shared/eventPlugins/TapEventPlugin.js b/src/renderers/dom/shared/eventPlugins/TapEventPlugin.js
index 8edd53ae60a..d081151cbd4 100644
--- a/src/renderers/dom/shared/eventPlugins/TapEventPlugin.js
+++ b/src/renderers/dom/shared/eventPlugins/TapEventPlugin.js
@@ -12,13 +12,10 @@
 
 'use strict';
 
-var EventPluginUtils = require('EventPluginUtils');
-var EventPropagators = require('EventPropagators');
-var SyntheticUIEvent = require('SyntheticUIEvent');
-var TouchEventUtils = require('fbjs/lib/TouchEventUtils');
-
-var isStartish = EventPluginUtils.isStartish;
-var isEndish = EventPluginUtils.isEndish;
+import {isStartish, isEndish} from 'EventPluginUtils';
+import {accumulateTwoPhaseDispatches} from 'EventPropagators';
+import SyntheticUIEvent from 'SyntheticUIEvent';
+import TouchEventUtils from 'fbjs/lib/TouchEventUtils';
 
 /**
  * We are extending the Flow 'Touch' declaration to enable using bracket
@@ -148,7 +145,7 @@ var TapEventPlugin = {
       startCoords.x = 0;
       startCoords.y = 0;
     }
-    EventPropagators.accumulateTwoPhaseDispatches(event);
+    accumulateTwoPhaseDispatches(event);
     return event;
   },
 };
diff --git a/src/renderers/dom/shared/findDOMNode.js b/src/renderers/dom/shared/findDOMNode.js
deleted file mode 100644
index e228ddb5e44..00000000000
--- a/src/renderers/dom/shared/findDOMNode.js
+++ /dev/null
@@ -1,91 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule findDOMNode
- * @flow
- */
-
-var ReactInstanceMap = require('ReactInstanceMap');
-var {ELEMENT_NODE} = require('HTMLNodeType');
-var {ReactCurrentOwner} = require('ReactGlobalSharedState');
-
-var getComponentName = require('getComponentName');
-var invariant = require('fbjs/lib/invariant');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
-let findFiber = function(arg) {
-  invariant(false, 'Missing injection for fiber findDOMNode');
-};
-let findStack = function(arg) {
-  invariant(false, 'Missing injection for stack findDOMNode');
-};
-
-const findDOMNode = function(
-  componentOrElement: Element | ?ReactComponent<any, any, any>,
-): null | Element | Text {
-  if (__DEV__) {
-    var owner = (ReactCurrentOwner.current: any);
-    if (owner !== null) {
-      var isFiber = typeof owner.tag === 'number';
-      var warnedAboutRefsInRender = isFiber
-        ? owner.stateNode._warnedAboutRefsInRender
-        : owner._warnedAboutRefsInRender;
-      warning(
-        warnedAboutRefsInRender,
-        '%s is accessing findDOMNode inside its render(). ' +
-          'render() should be a pure function of props and state. It should ' +
-          'never access something that requires stale data from the previous ' +
-          'render, such as refs. Move this logic to componentDidMount and ' +
-          'componentDidUpdate instead.',
-        getComponentName(owner) || 'A component',
-      );
-      if (isFiber) {
-        owner.stateNode._warnedAboutRefsInRender = true;
-      } else {
-        owner._warnedAboutRefsInRender = true;
-      }
-    }
-  }
-  if (componentOrElement == null) {
-    return null;
-  }
-  if ((componentOrElement: any).nodeType === ELEMENT_NODE) {
-    return (componentOrElement: any);
-  }
-
-  var inst = ReactInstanceMap.get(componentOrElement);
-  if (inst) {
-    if (typeof inst.tag === 'number') {
-      return findFiber(inst);
-    } else {
-      return findStack(inst);
-    }
-  }
-
-  if (typeof componentOrElement.render === 'function') {
-    invariant(false, 'Unable to find node on an unmounted component.');
-  } else {
-    invariant(
-      false,
-      'Element appears to be neither ReactComponent nor DOMNode. Keys: %s',
-      Object.keys(componentOrElement),
-    );
-  }
-};
-
-findDOMNode._injectFiber = function(fn) {
-  findFiber = fn;
-};
-findDOMNode._injectStack = function(fn) {
-  findStack = fn;
-};
-
-module.exports = findDOMNode;
diff --git a/src/renderers/dom/shared/hooks/ReactDOMInvalidARIAHook.js b/src/renderers/dom/shared/hooks/ReactDOMInvalidARIAHook.js
index a2ce43f7616..d7d19b1c4c5 100644
--- a/src/renderers/dom/shared/hooks/ReactDOMInvalidARIAHook.js
+++ b/src/renderers/dom/shared/hooks/ReactDOMInvalidARIAHook.js
@@ -11,37 +11,21 @@
 
 'use strict';
 
-var DOMProperty = require('DOMProperty');
+import {ATTRIBUTE_NAME_CHAR} from 'DOMProperty';
+import warning from 'fbjs/lib/warning';
+import {ReactDebugCurrentFrame} from 'ReactGlobalSharedState';
+import validAriaProperties from './validAriaProperties';
 
 var warnedProperties = {};
-var rARIA = new RegExp('^(aria)-[' + DOMProperty.ATTRIBUTE_NAME_CHAR + ']*$');
-var rARIACamel = new RegExp(
-  '^(aria)[A-Z][' + DOMProperty.ATTRIBUTE_NAME_CHAR + ']*$',
-);
+var rARIA = new RegExp('^(aria)-[' + ATTRIBUTE_NAME_CHAR + ']*$');
+var rARIACamel = new RegExp('^(aria)[A-Z][' + ATTRIBUTE_NAME_CHAR + ']*$');
 
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var {
-    ReactComponentTreeHook,
-    ReactDebugCurrentFrame,
-  } = require('ReactGlobalSharedState');
-  var {getStackAddendumByID} = ReactComponentTreeHook;
-
-  var validAriaProperties = require('./validAriaProperties');
-}
-
-function getStackAddendum(debugID) {
-  if (debugID != null) {
-    // This can only happen on Stack
-    return getStackAddendumByID(debugID);
-  } else {
-    // This can only happen on Fiber / Server
-    var stack = ReactDebugCurrentFrame.getStackAddendum();
-    return stack != null ? stack : '';
-  }
+function getStackAddendum() {
+  var stack = ReactDebugCurrentFrame.getStackAddendum();
+  return stack != null ? stack : '';
 }
 
-function validateProperty(tagName, name, debugID) {
+function validateProperty(tagName, name) {
   if (warnedProperties.hasOwnProperty(name) && warnedProperties[name]) {
     return true;
   }
@@ -59,7 +43,7 @@ function validateProperty(tagName, name, debugID) {
         false,
         'Invalid ARIA attribute `%s`. ARIA attributes follow the pattern aria-* and must be lowercase.%s',
         name,
-        getStackAddendum(debugID),
+        getStackAddendum(),
       );
       warnedProperties[name] = true;
       return true;
@@ -71,7 +55,7 @@ function validateProperty(tagName, name, debugID) {
         'Invalid ARIA attribute `%s`. Did you mean `%s`?%s',
         name,
         correctName,
-        getStackAddendum(debugID),
+        getStackAddendum(),
       );
       warnedProperties[name] = true;
       return true;
@@ -97,7 +81,7 @@ function validateProperty(tagName, name, debugID) {
         'Unknown ARIA attribute `%s`. Did you mean `%s`?%s',
         name,
         standardName,
-        getStackAddendum(debugID),
+        getStackAddendum(),
       );
       warnedProperties[name] = true;
       return true;
@@ -107,11 +91,11 @@ function validateProperty(tagName, name, debugID) {
   return true;
 }
 
-function warnInvalidARIAProps(type, props, debugID) {
+function warnInvalidARIAProps(type, props) {
   const invalidProps = [];
 
   for (var key in props) {
-    var isValid = validateProperty(type, key, debugID);
+    var isValid = validateProperty(type, key);
     if (!isValid) {
       invalidProps.push(key);
     }
@@ -128,7 +112,7 @@ function warnInvalidARIAProps(type, props, debugID) {
         'For details, see https://fb.me/invalid-aria-prop%s',
       unknownPropString,
       type,
-      getStackAddendum(debugID),
+      getStackAddendum(),
     );
   } else if (invalidProps.length > 1) {
     warning(
@@ -137,32 +121,14 @@ function warnInvalidARIAProps(type, props, debugID) {
         'For details, see https://fb.me/invalid-aria-prop%s',
       unknownPropString,
       type,
-      getStackAddendum(debugID),
+      getStackAddendum(),
     );
   }
 }
 
-function validateProperties(type, props, debugID /* Stack only */) {
+export function validateProperties(type, props) {
   if (type.indexOf('-') >= 0 || props.is) {
     return;
   }
-  warnInvalidARIAProps(type, props, debugID);
+  warnInvalidARIAProps(type, props);
 }
-
-var ReactDOMInvalidARIAHook = {
-  // Fiber
-  validateProperties,
-  // Stack
-  onBeforeMountComponent(debugID, element) {
-    if (__DEV__ && element != null && typeof element.type === 'string') {
-      validateProperties(element.type, element.props, debugID);
-    }
-  },
-  onBeforeUpdateComponent(debugID, element) {
-    if (__DEV__ && element != null && typeof element.type === 'string') {
-      validateProperties(element.type, element.props, debugID);
-    }
-  },
-};
-
-module.exports = ReactDOMInvalidARIAHook;
diff --git a/src/renderers/dom/shared/hooks/ReactDOMNullInputValuePropHook.js b/src/renderers/dom/shared/hooks/ReactDOMNullInputValuePropHook.js
index 905e30b13e4..d5204576fae 100644
--- a/src/renderers/dom/shared/hooks/ReactDOMNullInputValuePropHook.js
+++ b/src/renderers/dom/shared/hooks/ReactDOMNullInputValuePropHook.js
@@ -11,29 +11,17 @@
 
 'use strict';
 
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var {
-    ReactComponentTreeHook,
-    ReactDebugCurrentFrame,
-  } = require('ReactGlobalSharedState');
-  var {getStackAddendumByID} = ReactComponentTreeHook;
-}
+import warning from 'fbjs/lib/warning';
+import {ReactDebugCurrentFrame} from 'ReactGlobalSharedState';
 
 var didWarnValueNull = false;
 
-function getStackAddendum(debugID) {
-  if (debugID != null) {
-    // This can only happen on Stack
-    return getStackAddendumByID(debugID);
-  } else {
-    // This can only happen on Fiber / Server
-    var stack = ReactDebugCurrentFrame.getStackAddendum();
-    return stack != null ? stack : '';
-  }
+function getStackAddendum() {
+  var stack = ReactDebugCurrentFrame.getStackAddendum();
+  return stack != null ? stack : '';
 }
 
-function validateProperties(type, props, debugID /* Stack only */) {
+export function validateProperties(type, props) {
   if (type !== 'input' && type !== 'textarea' && type !== 'select') {
     return;
   }
@@ -44,27 +32,9 @@ function validateProperties(type, props, debugID /* Stack only */) {
         'Consider using the empty string to clear the component or `undefined` ' +
         'for uncontrolled components.%s',
       type,
-      getStackAddendum(debugID),
+      getStackAddendum(),
     );
 
     didWarnValueNull = true;
   }
 }
-
-var ReactDOMNullInputValuePropHook = {
-  // Fiber
-  validateProperties,
-  // Stack
-  onBeforeMountComponent(debugID, element) {
-    if (__DEV__ && element != null && typeof element.type === 'string') {
-      validateProperties(element.type, element.props, debugID);
-    }
-  },
-  onBeforeUpdateComponent(debugID, element) {
-    if (__DEV__ && element != null && typeof element.type === 'string') {
-      validateProperties(element.type, element.props, debugID);
-    }
-  },
-};
-
-module.exports = ReactDOMNullInputValuePropHook;
diff --git a/src/renderers/dom/shared/hooks/ReactDOMUnknownPropertyHook.js b/src/renderers/dom/shared/hooks/ReactDOMUnknownPropertyHook.js
index 113bb6049eb..532b5111fed 100644
--- a/src/renderers/dom/shared/hooks/ReactDOMUnknownPropertyHook.js
+++ b/src/renderers/dom/shared/hooks/ReactDOMUnknownPropertyHook.js
@@ -11,58 +11,46 @@
 
 'use strict';
 
-var DOMProperty = require('DOMProperty');
-var EventPluginRegistry = require('EventPluginRegistry');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var {
-    ReactComponentTreeHook,
-    ReactDebugCurrentFrame,
-  } = require('ReactGlobalSharedState');
-  var {getStackAddendumByID} = ReactComponentTreeHook;
-}
-
-function getStackAddendum(debugID) {
-  if (debugID != null) {
-    // This can only happen on Stack
-    return getStackAddendumByID(debugID);
-  } else {
-    // This can only happen on Fiber / Server
-    var stack = ReactDebugCurrentFrame.getStackAddendum();
-    return stack != null ? stack : '';
-  }
+import {isReservedProp, shouldSetAttribute} from 'DOMProperty';
+import {
+  registrationNameModules,
+  plugins,
+  possibleRegistrationNames,
+} from 'EventPluginRegistry';
+import warning from 'fbjs/lib/warning';
+import {ReactDebugCurrentFrame} from 'ReactGlobalSharedState';
+import possibleStandardNames from 'possibleStandardNames';
+
+function getStackAddendum() {
+  var stack = ReactDebugCurrentFrame.getStackAddendum();
+  return stack != null ? stack : '';
 }
 
 if (__DEV__) {
   var warnedProperties = {};
   var EVENT_NAME_REGEX = /^on[A-Z]/;
   var ARIA_NAME_REGEX = /^aria-/i;
-  var possibleStandardNames = require('possibleStandardNames');
 
-  var validateProperty = function(tagName, name, value, debugID) {
+  var validateProperty = function(tagName, name, value) {
     if (warnedProperties.hasOwnProperty(name) && warnedProperties[name]) {
       return true;
     }
 
-    if (EventPluginRegistry.registrationNameModules.hasOwnProperty(name)) {
+    if (registrationNameModules.hasOwnProperty(name)) {
       return true;
     }
 
-    if (
-      EventPluginRegistry.plugins.length === 0 &&
-      EVENT_NAME_REGEX.test(name)
-    ) {
+    if (plugins.length === 0 && EVENT_NAME_REGEX.test(name)) {
       // If no event plugins have been injected, we might be in a server environment.
       // Don't check events in this case.
       return true;
     }
 
     var lowerCasedName = name.toLowerCase();
-    var registrationName = EventPluginRegistry.possibleRegistrationNames.hasOwnProperty(
+    var registrationName = possibleRegistrationNames.hasOwnProperty(
       lowerCasedName,
     )
-      ? EventPluginRegistry.possibleRegistrationNames[lowerCasedName]
+      ? possibleRegistrationNames[lowerCasedName]
       : null;
 
     if (registrationName != null) {
@@ -71,7 +59,7 @@ if (__DEV__) {
         'Unknown event handler property `%s`. Did you mean `%s`?%s',
         name,
         registrationName,
-        getStackAddendum(debugID),
+        getStackAddendum(),
       );
       warnedProperties[name] = true;
       return true;
@@ -109,7 +97,7 @@ if (__DEV__) {
         'Received NaN for numeric attribute `%s`. If this is expected, cast ' +
           'the value to a string.%s',
         name,
-        getStackAddendum(debugID),
+        getStackAddendum(),
       );
       warnedProperties[name] = true;
       return true;
@@ -124,7 +112,7 @@ if (__DEV__) {
           'Invalid DOM property `%s`. Did you mean `%s`?%s',
           name,
           standardName,
-          getStackAddendum(debugID),
+          getStackAddendum(),
         );
         warnedProperties[name] = true;
         return true;
@@ -133,12 +121,12 @@ if (__DEV__) {
 
     // Now that we've validated casing, do not validate
     // data types for reserved props
-    if (DOMProperty.isReservedProp(name)) {
+    if (isReservedProp(name)) {
       return true;
     }
 
     // Warn when a known attribute is a bad type
-    if (!DOMProperty.shouldSetAttribute(name, value)) {
+    if (!shouldSetAttribute(name, value)) {
       warnedProperties[name] = true;
       return false;
     }
@@ -147,10 +135,10 @@ if (__DEV__) {
   };
 }
 
-var warnUnknownProperties = function(type, props, debugID) {
+var warnUnknownProperties = function(type, props) {
   var unknownProps = [];
   for (var key in props) {
-    var isValid = validateProperty(type, key, props[key], debugID);
+    var isValid = validateProperty(type, key, props[key]);
     if (!isValid) {
       unknownProps.push(key);
       var value = props[key];
@@ -162,7 +150,7 @@ var warnUnknownProperties = function(type, props, debugID) {
             'DOM after a future React update.%s',
           key,
           type,
-          getStackAddendum(debugID),
+          getStackAddendum(),
         );
       }
     }
@@ -178,7 +166,7 @@ var warnUnknownProperties = function(type, props, debugID) {
         'For details, see https://fb.me/react-unknown-prop%s',
       unknownPropString,
       type,
-      getStackAddendum(debugID),
+      getStackAddendum(),
     );
   } else if (unknownProps.length > 1) {
     warning(
@@ -188,32 +176,14 @@ var warnUnknownProperties = function(type, props, debugID) {
         'For details, see https://fb.me/react-unknown-prop%s',
       unknownPropString,
       type,
-      getStackAddendum(debugID),
+      getStackAddendum(),
     );
   }
 };
 
-function validateProperties(type, props, debugID /* Stack only */) {
+export function validateProperties(type, props) {
   if (type.indexOf('-') >= 0 || props.is) {
     return;
   }
-  warnUnknownProperties(type, props, debugID);
+  warnUnknownProperties(type, props);
 }
-
-var ReactDOMUnknownPropertyHook = {
-  // Fiber
-  validateProperties,
-  // Stack
-  onBeforeMountComponent(debugID, element) {
-    if (__DEV__ && element != null && typeof element.type === 'string') {
-      validateProperties(element.type, element.props, debugID);
-    }
-  },
-  onBeforeUpdateComponent(debugID, element) {
-    if (__DEV__ && element != null && typeof element.type === 'string') {
-      validateProperties(element.type, element.props, debugID);
-    }
-  },
-};
-
-module.exports = ReactDOMUnknownPropertyHook;
diff --git a/src/renderers/dom/shared/hooks/possibleStandardNames.js b/src/renderers/dom/shared/hooks/possibleStandardNames.js
index 2d0a81771ec..f6e71336b75 100644
--- a/src/renderers/dom/shared/hooks/possibleStandardNames.js
+++ b/src/renderers/dom/shared/hooks/possibleStandardNames.js
@@ -497,4 +497,4 @@ var possibleStandardNames = {
   zoomandpan: 'zoomAndPan',
 };
 
-module.exports = possibleStandardNames;
+export default possibleStandardNames;
diff --git a/src/renderers/dom/shared/hooks/validAriaProperties.js b/src/renderers/dom/shared/hooks/validAriaProperties.js
index 9a75a6201b8..753ed1e8397 100644
--- a/src/renderers/dom/shared/hooks/validAriaProperties.js
+++ b/src/renderers/dom/shared/hooks/validAriaProperties.js
@@ -66,4 +66,4 @@ var ariaProperties = {
   'aria-setsize': 0,
 };
 
-module.exports = ariaProperties;
+export default ariaProperties;
diff --git a/src/renderers/dom/shared/inputValueTracking.js b/src/renderers/dom/shared/inputValueTracking.js
index 152c793b39a..502f3aba83d 100644
--- a/src/renderers/dom/shared/inputValueTracking.js
+++ b/src/renderers/dom/shared/inputValueTracking.js
@@ -101,46 +101,42 @@ function trackValueOnNode(node: any): ?ValueTracker {
   return tracker;
 }
 
-var inputValueTracking = {
-  // exposed for testing
-  _getTrackerFromNode: getTracker,
-
-  track(node: ElementWithValueTracker) {
-    if (getTracker(node)) {
-      return;
-    }
-
-    // TODO: Once it's just Fiber we can move this to node._wrapperState
-    node._valueTracker = trackValueOnNode(node);
-  },
-
-  updateValueIfChanged(node: ElementWithValueTracker) {
-    if (!node) {
-      return false;
-    }
-
-    var tracker = getTracker(node);
-    // if there is no tracker at this point it's unlikely
-    // that trying again will succeed
-    if (!tracker) {
-      return true;
-    }
-
-    var lastValue = tracker.getValue();
-    var nextValue = getValueFromNode(node);
-    if (nextValue !== lastValue) {
-      tracker.setValue(nextValue);
-      return true;
-    }
+// exposed for testing
+export const _getTrackerFromNode = getTracker;
+
+export function track(node: ElementWithValueTracker) {
+  if (getTracker(node)) {
+    return;
+  }
+
+  // TODO: Once it's just Fiber we can move this to node._wrapperState
+  node._valueTracker = trackValueOnNode(node);
+}
+
+export function updateValueIfChanged(node: ElementWithValueTracker) {
+  if (!node) {
     return false;
-  },
-
-  stopTracking(node: ElementWithValueTracker) {
-    var tracker = getTracker(node);
-    if (tracker) {
-      tracker.stopTracking();
-    }
-  },
-};
+  }
+
+  var tracker = getTracker(node);
+  // if there is no tracker at this point it's unlikely
+  // that trying again will succeed
+  if (!tracker) {
+    return true;
+  }
+
+  var lastValue = tracker.getValue();
+  var nextValue = getValueFromNode(node);
+  if (nextValue !== lastValue) {
+    tracker.setValue(nextValue);
+    return true;
+  }
+  return false;
+}
 
-module.exports = inputValueTracking;
+export function stopTracking(node: ElementWithValueTracker) {
+  var tracker = getTracker(node);
+  if (tracker) {
+    tracker.stopTracking();
+  }
+}
diff --git a/src/renderers/dom/shared/quoteAttributeValueForBrowser.js b/src/renderers/dom/shared/quoteAttributeValueForBrowser.js
index ede81daaf09..1a3ac850f4a 100644
--- a/src/renderers/dom/shared/quoteAttributeValueForBrowser.js
+++ b/src/renderers/dom/shared/quoteAttributeValueForBrowser.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var escapeTextContentForBrowser = require('escapeTextContentForBrowser');
+import escapeTextContentForBrowser from 'escapeTextContentForBrowser';
 
 /**
  * Escapes attribute value to prevent scripting attacks.
@@ -23,4 +23,4 @@ function quoteAttributeValueForBrowser(value) {
   return '"' + escapeTextContentForBrowser(value) + '"';
 }
 
-module.exports = quoteAttributeValueForBrowser;
+export default quoteAttributeValueForBrowser;
diff --git a/src/renderers/dom/shared/renderSubtreeIntoContainer.js b/src/renderers/dom/shared/renderSubtreeIntoContainer.js
deleted file mode 100644
index f69b3cc3e46..00000000000
--- a/src/renderers/dom/shared/renderSubtreeIntoContainer.js
+++ /dev/null
@@ -1,16 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule renderSubtreeIntoContainer
- */
-
-'use strict';
-
-var ReactDOM = require('ReactDOM');
-
-module.exports = ReactDOM.unstable_renderSubtreeIntoContainer;
diff --git a/src/renderers/dom/shared/setInnerHTML.js b/src/renderers/dom/shared/setInnerHTML.js
index f2645392d8f..95c3832acce 100644
--- a/src/renderers/dom/shared/setInnerHTML.js
+++ b/src/renderers/dom/shared/setInnerHTML.js
@@ -11,8 +11,9 @@
 
 'use strict';
 
-var Namespaces = require('DOMNamespaces').Namespaces;
-var createMicrosoftUnsafeLocalFunction = require('createMicrosoftUnsafeLocalFunction');
+import {Namespaces} from 'DOMNamespaces';
+import createMicrosoftUnsafeLocalFunction
+  from 'createMicrosoftUnsafeLocalFunction';
 
 // SVG temp container for IE lacking innerHTML
 var reusableSVGContainer;
@@ -24,7 +25,7 @@ var reusableSVGContainer;
  * @param {string} html
  * @internal
  */
-var setInnerHTML = createMicrosoftUnsafeLocalFunction(function(node, html) {
+const setInnerHTML = createMicrosoftUnsafeLocalFunction(function(node, html) {
   // IE does not have innerHTML for SVG nodes, so instead we inject the
   // new markup in a temp node and then move the child nodes across into
   // the target node
@@ -41,4 +42,4 @@ var setInnerHTML = createMicrosoftUnsafeLocalFunction(function(node, html) {
   }
 });
 
-module.exports = setInnerHTML;
+export default setInnerHTML;
diff --git a/src/renderers/dom/shared/setTextContent.js b/src/renderers/dom/shared/setTextContent.js
index cef8fbc78e9..c4b11cb4475 100644
--- a/src/renderers/dom/shared/setTextContent.js
+++ b/src/renderers/dom/shared/setTextContent.js
@@ -11,10 +11,10 @@
 
 'use strict';
 
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
-var escapeTextContentForBrowser = require('escapeTextContentForBrowser');
-var setInnerHTML = require('setInnerHTML');
-var {TEXT_NODE} = require('HTMLNodeType');
+import ExecutionEnvironment from 'fbjs/lib/ExecutionEnvironment';
+import escapeTextContentForBrowser from 'escapeTextContentForBrowser';
+import setInnerHTML from 'setInnerHTML';
+import {TEXT_NODE} from 'HTMLNodeType';
 
 /**
  * Set the textContent property of a node, ensuring that whitespace is preserved
@@ -26,7 +26,7 @@ var {TEXT_NODE} = require('HTMLNodeType');
  * @param {string} text
  * @internal
  */
-var setTextContent = function(node, text) {
+let setTextContent = function(node, text) {
   if (text) {
     var firstChild = node.firstChild;
 
@@ -42,6 +42,8 @@ var setTextContent = function(node, text) {
   node.textContent = text;
 };
 
+export default setTextContent;
+
 if (ExecutionEnvironment.canUseDOM) {
   if (!('textContent' in document.documentElement)) {
     setTextContent = function(node, text) {
@@ -53,5 +55,3 @@ if (ExecutionEnvironment.canUseDOM) {
     };
   }
 }
-
-module.exports = setTextContent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticAnimationEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticAnimationEvent.js
index 1a6925a11ba..c2506c6c85d 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticAnimationEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticAnimationEvent.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var SyntheticEvent = require('SyntheticEvent');
+import SyntheticEvent from 'SyntheticEvent';
 
 /**
  * @interface Event
@@ -47,4 +47,4 @@ function SyntheticAnimationEvent(
 
 SyntheticEvent.augmentClass(SyntheticAnimationEvent, AnimationEventInterface);
 
-module.exports = SyntheticAnimationEvent;
+export default SyntheticAnimationEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticClipboardEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticClipboardEvent.js
index e277334b641..62f55e860ca 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticClipboardEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticClipboardEvent.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var SyntheticEvent = require('SyntheticEvent');
+import SyntheticEvent from 'SyntheticEvent';
 
 /**
  * @interface Event
@@ -48,4 +48,4 @@ function SyntheticClipboardEvent(
 
 SyntheticEvent.augmentClass(SyntheticClipboardEvent, ClipboardEventInterface);
 
-module.exports = SyntheticClipboardEvent;
+export default SyntheticClipboardEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticCompositionEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticCompositionEvent.js
index 77c53c5c9d6..192481259c7 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticCompositionEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticCompositionEvent.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var SyntheticEvent = require('SyntheticEvent');
+import SyntheticEvent from 'SyntheticEvent';
 
 /**
  * @interface Event
@@ -47,4 +47,4 @@ SyntheticEvent.augmentClass(
   CompositionEventInterface,
 );
 
-module.exports = SyntheticCompositionEvent;
+export default SyntheticCompositionEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticDragEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticDragEvent.js
index 3f74638f93a..8cef6f05fdd 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticDragEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticDragEvent.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var SyntheticMouseEvent = require('SyntheticMouseEvent');
+import SyntheticMouseEvent from 'SyntheticMouseEvent';
 
 /**
  * @interface DragEvent
@@ -44,4 +44,4 @@ function SyntheticDragEvent(
 
 SyntheticMouseEvent.augmentClass(SyntheticDragEvent, DragEventInterface);
 
-module.exports = SyntheticDragEvent;
+export default SyntheticDragEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticFocusEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticFocusEvent.js
index de0616834be..170d8001847 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticFocusEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticFocusEvent.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var SyntheticUIEvent = require('SyntheticUIEvent');
+import SyntheticUIEvent from 'SyntheticUIEvent';
 
 /**
  * @interface FocusEvent
@@ -44,4 +44,4 @@ function SyntheticFocusEvent(
 
 SyntheticUIEvent.augmentClass(SyntheticFocusEvent, FocusEventInterface);
 
-module.exports = SyntheticFocusEvent;
+export default SyntheticFocusEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticInputEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticInputEvent.js
index 2639d3b53b3..c52971a90df 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticInputEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticInputEvent.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var SyntheticEvent = require('SyntheticEvent');
+import SyntheticEvent from 'SyntheticEvent';
 
 /**
  * @interface Event
@@ -45,4 +45,4 @@ function SyntheticInputEvent(
 
 SyntheticEvent.augmentClass(SyntheticInputEvent, InputEventInterface);
 
-module.exports = SyntheticInputEvent;
+export default SyntheticInputEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticKeyboardEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticKeyboardEvent.js
index 8cc554b9361..48b33ec4494 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticKeyboardEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticKeyboardEvent.js
@@ -11,11 +11,11 @@
 
 'use strict';
 
-var SyntheticUIEvent = require('SyntheticUIEvent');
+import SyntheticUIEvent from 'SyntheticUIEvent';
 
-var getEventCharCode = require('getEventCharCode');
-var getEventKey = require('getEventKey');
-var getEventModifierState = require('getEventModifierState');
+import getEventCharCode from 'getEventCharCode';
+import getEventKey from 'getEventKey';
+import getEventModifierState from 'getEventModifierState';
 
 /**
  * @interface KeyboardEvent
@@ -92,4 +92,4 @@ function SyntheticKeyboardEvent(
 
 SyntheticUIEvent.augmentClass(SyntheticKeyboardEvent, KeyboardEventInterface);
 
-module.exports = SyntheticKeyboardEvent;
+export default SyntheticKeyboardEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticMouseEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticMouseEvent.js
index 428ec754aa9..741c7bee019 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticMouseEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticMouseEvent.js
@@ -11,9 +11,9 @@
 
 'use strict';
 
-var SyntheticUIEvent = require('SyntheticUIEvent');
+import SyntheticUIEvent from 'SyntheticUIEvent';
 
-var getEventModifierState = require('getEventModifierState');
+import getEventModifierState from 'getEventModifierState';
 
 /**
  * @interface MouseEvent
@@ -66,4 +66,4 @@ function SyntheticMouseEvent(
 
 SyntheticUIEvent.augmentClass(SyntheticMouseEvent, MouseEventInterface);
 
-module.exports = SyntheticMouseEvent;
+export default SyntheticMouseEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticTouchEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticTouchEvent.js
index a954c9fec17..eb10960eff2 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticTouchEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticTouchEvent.js
@@ -11,9 +11,9 @@
 
 'use strict';
 
-var SyntheticUIEvent = require('SyntheticUIEvent');
+import SyntheticUIEvent from 'SyntheticUIEvent';
 
-var getEventModifierState = require('getEventModifierState');
+import getEventModifierState from 'getEventModifierState';
 
 /**
  * @interface TouchEvent
@@ -53,4 +53,4 @@ function SyntheticTouchEvent(
 
 SyntheticUIEvent.augmentClass(SyntheticTouchEvent, TouchEventInterface);
 
-module.exports = SyntheticTouchEvent;
+export default SyntheticTouchEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticTransitionEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticTransitionEvent.js
index 4b9087a1cb7..46e483b6018 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticTransitionEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticTransitionEvent.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var SyntheticEvent = require('SyntheticEvent');
+import SyntheticEvent from 'SyntheticEvent';
 
 /**
  * @interface Event
@@ -47,4 +47,4 @@ function SyntheticTransitionEvent(
 
 SyntheticEvent.augmentClass(SyntheticTransitionEvent, TransitionEventInterface);
 
-module.exports = SyntheticTransitionEvent;
+export default SyntheticTransitionEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticUIEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticUIEvent.js
index 308d190481b..4ff0f3f7d68 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticUIEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticUIEvent.js
@@ -11,9 +11,9 @@
 
 'use strict';
 
-var SyntheticEvent = require('SyntheticEvent');
+import SyntheticEvent from 'SyntheticEvent';
 
-var getEventTarget = require('getEventTarget');
+import getEventTarget from 'getEventTarget';
 
 /**
  * @interface UIEvent
@@ -67,4 +67,4 @@ function SyntheticUIEvent(
 
 SyntheticEvent.augmentClass(SyntheticUIEvent, UIEventInterface);
 
-module.exports = SyntheticUIEvent;
+export default SyntheticUIEvent;
diff --git a/src/renderers/dom/shared/syntheticEvents/SyntheticWheelEvent.js b/src/renderers/dom/shared/syntheticEvents/SyntheticWheelEvent.js
index 76a0d67ac99..e636d720362 100644
--- a/src/renderers/dom/shared/syntheticEvents/SyntheticWheelEvent.js
+++ b/src/renderers/dom/shared/syntheticEvents/SyntheticWheelEvent.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var SyntheticMouseEvent = require('SyntheticMouseEvent');
+import SyntheticMouseEvent from 'SyntheticMouseEvent';
 
 /**
  * @interface WheelEvent
@@ -65,4 +65,4 @@ function SyntheticWheelEvent(
 
 SyntheticMouseEvent.augmentClass(SyntheticWheelEvent, WheelEventInterface);
 
-module.exports = SyntheticWheelEvent;
+export default SyntheticWheelEvent;
diff --git a/src/renderers/dom/shared/utils/AutoFocusUtils.js b/src/renderers/dom/shared/utils/AutoFocusUtils.js
index 43a99bc3ead..a7708bebd5a 100644
--- a/src/renderers/dom/shared/utils/AutoFocusUtils.js
+++ b/src/renderers/dom/shared/utils/AutoFocusUtils.js
@@ -11,14 +11,9 @@
 
 'use strict';
 
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
+import {getNodeFromInstance} from 'ReactDOMComponentTree';
+import focusNode from 'fbjs/lib/focusNode';
 
-var focusNode = require('fbjs/lib/focusNode');
-
-var AutoFocusUtils = {
-  focusDOMComponent: function() {
-    focusNode(ReactDOMComponentTree.getNodeFromInstance(this));
-  },
-};
-
-module.exports = AutoFocusUtils;
+export function focusDOMComponent() {
+  focusNode(getNodeFromInstance(this));
+}
diff --git a/src/renderers/dom/shared/utils/ReactControlledValuePropTypes.js b/src/renderers/dom/shared/utils/ReactControlledValuePropTypes.js
index 15dc10954ab..f2b64423294 100644
--- a/src/renderers/dom/shared/utils/ReactControlledValuePropTypes.js
+++ b/src/renderers/dom/shared/utils/ReactControlledValuePropTypes.js
@@ -11,17 +11,11 @@
 
 'use strict';
 
-var ReactControlledValuePropTypes = {
-  checkPropTypes: null,
-};
+import warning from 'fbjs/lib/warning';
+import PropTypes from 'prop-types';
 
 if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var emptyFunction = require('fbjs/lib/emptyFunction');
-  var PropTypes = require('prop-types');
   var ReactPropTypesSecret = 'SECRET_DO_NOT_PASS_THIS_OR_YOU_WILL_BE_FIRED';
-
-  ReactControlledValuePropTypes.checkPropTypes = emptyFunction;
   var hasReadOnlyValue = {
     button: true,
     checkbox: true,
@@ -31,7 +25,6 @@ if (__DEV__) {
     reset: true,
     submit: true,
   };
-
   var propTypes = {
     value: function(props, propName, componentName) {
       if (
@@ -68,18 +61,15 @@ if (__DEV__) {
     },
     onChange: PropTypes.func,
   };
-
   var loggedTypeFailures = {};
+}
 
-  /**
-   * Provide a linked `value` attribute for controlled forms. You should not use
-   * this outside of the ReactDOM controlled form components.
-   */
-  ReactControlledValuePropTypes.checkPropTypes = function(
-    tagName,
-    props,
-    getStack,
-  ) {
+/**
+ * Provide a linked `value` attribute for controlled forms. You should not use
+ * this outside of the ReactDOM controlled form components.
+ */
+export function checkPropTypes(tagName, props, getStack) {
+  if (__DEV__) {
     for (var propName in propTypes) {
       if (propTypes.hasOwnProperty(propName)) {
         var error = propTypes[propName](
@@ -99,7 +89,5 @@ if (__DEV__) {
         warning(false, 'Failed form propType: %s%s', error.message, getStack());
       }
     }
-  };
+  }
 }
-
-module.exports = ReactControlledValuePropTypes;
diff --git a/src/renderers/dom/shared/utils/assertValidProps.js b/src/renderers/dom/shared/utils/assertValidProps.js
index 5de6bf0032b..916531578c3 100644
--- a/src/renderers/dom/shared/utils/assertValidProps.js
+++ b/src/renderers/dom/shared/utils/assertValidProps.js
@@ -11,12 +11,9 @@
 
 'use strict';
 
-var invariant = require('fbjs/lib/invariant');
-var voidElementTags = require('voidElementTags');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import invariant from 'fbjs/lib/invariant';
+import voidElementTags from 'voidElementTags';
+import warning from 'fbjs/lib/warning';
 
 var HTML = '__html';
 
@@ -31,7 +28,7 @@ function getDeclarationErrorAddendum(getCurrentOwnerName) {
   return '';
 }
 
-function assertValidProps(
+export default function assertValidProps(
   tag: string,
   props: ?Object,
   getCurrentOwnerName: () => ?string,
@@ -81,5 +78,3 @@ function assertValidProps(
     getDeclarationErrorAddendum(getCurrentOwnerName),
   );
 }
-
-module.exports = assertValidProps;
diff --git a/src/renderers/dom/shared/utils/getEventCharCode.js b/src/renderers/dom/shared/utils/getEventCharCode.js
index 5d07dfdc7f6..5b13af6e925 100644
--- a/src/renderers/dom/shared/utils/getEventCharCode.js
+++ b/src/renderers/dom/shared/utils/getEventCharCode.js
@@ -21,7 +21,7 @@
  * @param {object} nativeEvent Native browser event.
  * @return {number} Normalized `charCode` property.
  */
-function getEventCharCode(nativeEvent) {
+export default function getEventCharCode(nativeEvent) {
   var charCode;
   var keyCode = nativeEvent.keyCode;
 
@@ -45,5 +45,3 @@ function getEventCharCode(nativeEvent) {
 
   return 0;
 }
-
-module.exports = getEventCharCode;
diff --git a/src/renderers/dom/shared/utils/getEventKey.js b/src/renderers/dom/shared/utils/getEventKey.js
index 19786e778dd..126b714b1e7 100644
--- a/src/renderers/dom/shared/utils/getEventKey.js
+++ b/src/renderers/dom/shared/utils/getEventKey.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var getEventCharCode = require('getEventCharCode');
+import getEventCharCode from 'getEventCharCode';
 
 /**
  * Normalization of deprecated HTML5 `key` values
@@ -80,7 +80,7 @@ var translateToKey = {
  * @param {object} nativeEvent Native browser event.
  * @return {string} Normalized `key` property.
  */
-function getEventKey(nativeEvent) {
+export default function getEventKey(nativeEvent) {
   if (nativeEvent.key) {
     // Normalize inconsistent values reported by browsers due to
     // implementations of a working draft specification.
@@ -108,5 +108,3 @@ function getEventKey(nativeEvent) {
   }
   return '';
 }
-
-module.exports = getEventKey;
diff --git a/src/renderers/dom/shared/utils/getEventModifierState.js b/src/renderers/dom/shared/utils/getEventModifierState.js
index cafcf69e4b5..7220246ae5d 100644
--- a/src/renderers/dom/shared/utils/getEventModifierState.js
+++ b/src/renderers/dom/shared/utils/getEventModifierState.js
@@ -36,8 +36,6 @@ function modifierStateGetter(keyArg) {
   return keyProp ? !!nativeEvent[keyProp] : false;
 }
 
-function getEventModifierState(nativeEvent) {
+export default function getEventModifierState(nativeEvent) {
   return modifierStateGetter;
 }
-
-module.exports = getEventModifierState;
diff --git a/src/renderers/dom/shared/utils/getEventTarget.js b/src/renderers/dom/shared/utils/getEventTarget.js
index bcd806aec48..6e62225bea2 100644
--- a/src/renderers/dom/shared/utils/getEventTarget.js
+++ b/src/renderers/dom/shared/utils/getEventTarget.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var {TEXT_NODE} = require('HTMLNodeType');
+import {TEXT_NODE} from 'HTMLNodeType';
 
 /**
  * Gets the target node from a native browser event by accounting for
@@ -20,7 +20,7 @@ var {TEXT_NODE} = require('HTMLNodeType');
  * @param {object} nativeEvent Native browser event.
  * @return {DOMEventTarget} Target node.
  */
-function getEventTarget(nativeEvent) {
+export default function getEventTarget(nativeEvent) {
   var target = nativeEvent.target || nativeEvent.srcElement || window;
 
   // Normalize SVG <use> element events #4963
@@ -32,5 +32,3 @@ function getEventTarget(nativeEvent) {
   // @see http://www.quirksmode.org/js/events_properties.html
   return target.nodeType === TEXT_NODE ? target.parentNode : target;
 }
-
-module.exports = getEventTarget;
diff --git a/src/renderers/dom/shared/utils/getNodeForCharacterOffset.js b/src/renderers/dom/shared/utils/getNodeForCharacterOffset.js
index 4a300293f91..1a69cd7fc07 100644
--- a/src/renderers/dom/shared/utils/getNodeForCharacterOffset.js
+++ b/src/renderers/dom/shared/utils/getNodeForCharacterOffset.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var {TEXT_NODE} = require('HTMLNodeType');
+import {TEXT_NODE} from 'HTMLNodeType';
 
 /**
  * Given any node return the first leaf node without children.
@@ -49,7 +49,7 @@ function getSiblingNode(node) {
  * @param {number} offset
  * @return {?object}
  */
-function getNodeForCharacterOffset(root, offset) {
+export default function getNodeForCharacterOffset(root, offset) {
   var node = getLeafNode(root);
   var nodeStart = 0;
   var nodeEnd = 0;
@@ -71,5 +71,3 @@ function getNodeForCharacterOffset(root, offset) {
     node = getLeafNode(getSiblingNode(node));
   }
 }
-
-module.exports = getNodeForCharacterOffset;
diff --git a/src/renderers/dom/shared/utils/getTextContentAccessor.js b/src/renderers/dom/shared/utils/getTextContentAccessor.js
index cfc945902ea..d97a06c4c08 100644
--- a/src/renderers/dom/shared/utils/getTextContentAccessor.js
+++ b/src/renderers/dom/shared/utils/getTextContentAccessor.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
+import ExecutionEnvironment from 'fbjs/lib/ExecutionEnvironment';
 
 var contentKey = null;
 
@@ -32,4 +32,4 @@ function getTextContentAccessor() {
   return contentKey;
 }
 
-module.exports = getTextContentAccessor;
+export default getTextContentAccessor;
diff --git a/src/renderers/dom/shared/utils/isCustomComponent.js b/src/renderers/dom/shared/utils/isCustomComponent.js
index 2563a1e2b5a..289715012fb 100644
--- a/src/renderers/dom/shared/utils/isCustomComponent.js
+++ b/src/renderers/dom/shared/utils/isCustomComponent.js
@@ -11,8 +11,6 @@
 
 'use strict';
 
-function isCustomComponent(tagName, props) {
+export default function isCustomComponent(tagName, props) {
   return tagName.indexOf('-') >= 0 || props.is != null;
 }
-
-module.exports = isCustomComponent;
diff --git a/src/renderers/dom/shared/utils/isEventSupported.js b/src/renderers/dom/shared/utils/isEventSupported.js
index a5eee44c855..fdfedcce185 100644
--- a/src/renderers/dom/shared/utils/isEventSupported.js
+++ b/src/renderers/dom/shared/utils/isEventSupported.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
+import ExecutionEnvironment from 'fbjs/lib/ExecutionEnvironment';
 
 var useHasFeature;
 if (ExecutionEnvironment.canUseDOM) {
@@ -62,4 +62,4 @@ function isEventSupported(eventNameSuffix, capture) {
   return isSupported;
 }
 
-module.exports = isEventSupported;
+export default isEventSupported;
diff --git a/src/renderers/dom/shared/utils/omittedCloseTags.js b/src/renderers/dom/shared/utils/omittedCloseTags.js
index b6884e24d76..ee8e4532227 100644
--- a/src/renderers/dom/shared/utils/omittedCloseTags.js
+++ b/src/renderers/dom/shared/utils/omittedCloseTags.js
@@ -33,4 +33,4 @@ var omittedCloseTags = {
   // NOTE: menuitem's close tag should be omitted, but that causes problems.
 };
 
-module.exports = omittedCloseTags;
+export default omittedCloseTags;
diff --git a/src/renderers/dom/shared/utils/voidElementTags.js b/src/renderers/dom/shared/utils/voidElementTags.js
index 80c2645c906..13a9cfd7481 100644
--- a/src/renderers/dom/shared/utils/voidElementTags.js
+++ b/src/renderers/dom/shared/utils/voidElementTags.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var omittedCloseTags = require('omittedCloseTags');
+import omittedCloseTags from 'omittedCloseTags';
 
 // For HTML, certain tags cannot have children. This has the same purpose as
 // `omittedCloseTags` except that `menuitem` should still have its closing tag.
@@ -21,4 +21,4 @@ var voidElementTags = {
   ...omittedCloseTags,
 };
 
-module.exports = voidElementTags;
+export default voidElementTags;
diff --git a/src/renderers/dom/shared/validateDOMNesting.js b/src/renderers/dom/shared/validateDOMNesting.js
index d5d32092979..97175a0def9 100644
--- a/src/renderers/dom/shared/validateDOMNesting.js
+++ b/src/renderers/dom/shared/validateDOMNesting.js
@@ -11,15 +11,15 @@
 
 'use strict';
 
-var emptyFunction = require('fbjs/lib/emptyFunction');
-var getComponentName = require('getComponentName');
+import emptyFunction from 'fbjs/lib/emptyFunction';
+import warning from 'fbjs/lib/warning';
+import {getCurrentFiberStackAddendum} from 'ReactDebugCurrentFiber';
 
-var validateDOMNesting = emptyFunction;
+export let updatedAncestorInfo = emptyFunction;
+export let validateDOMNesting = emptyFunction;
+export let isTagValidInContext = emptyFunction;
 
 if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var {getCurrentFiberStackAddendum} = require('ReactDebugCurrentFiber');
-
   // This validation code was written based on the HTML5 parsing spec:
   // https://html.spec.whatwg.org/multipage/syntax.html#has-an-element-in-scope
   //
@@ -166,7 +166,7 @@ if (__DEV__) {
     dlItemTagAutoclosing: null,
   };
 
-  var updatedAncestorInfo = function(oldInfo, tag, instance) {
+  updatedAncestorInfo = function(oldInfo, tag, instance) {
     var ancestorInfo = Object.assign({}, oldInfo || emptyAncestorInfo);
     var info = {tag: tag, instance: instance};
 
@@ -407,83 +407,9 @@ if (__DEV__) {
     return null;
   };
 
-  /**
-   * Given a ReactCompositeComponent instance, return a list of its recursive
-   * owners, starting at the root and ending with the instance itself.
-   */
-  var findOwnerStack = function(instance) {
-    if (!instance) {
-      return [];
-    }
-
-    var stack = [];
-    do {
-      stack.push(instance);
-    } while ((instance = instance._currentElement._owner));
-    stack.reverse();
-    return stack;
-  };
-
-  var getOwnerInfo = function(
-    childInstance,
-    childTag,
-    ancestorInstance,
-    ancestorTag,
-    isParent,
-  ) {
-    var childOwner = childInstance && childInstance._currentElement._owner;
-    var ancestorOwner =
-      ancestorInstance && ancestorInstance._currentElement._owner;
-
-    var childOwners = findOwnerStack(childOwner);
-    var ancestorOwners = findOwnerStack(ancestorOwner);
-
-    var minStackLen = Math.min(childOwners.length, ancestorOwners.length);
-    var i;
-
-    var deepestCommon = -1;
-    for (i = 0; i < minStackLen; i++) {
-      if (childOwners[i] === ancestorOwners[i]) {
-        deepestCommon = i;
-      } else {
-        break;
-      }
-    }
-
-    var UNKNOWN = '(unknown)';
-    var childOwnerNames = childOwners
-      .slice(deepestCommon + 1)
-      .map(inst => getComponentName(inst) || UNKNOWN);
-    var ancestorOwnerNames = ancestorOwners
-      .slice(deepestCommon + 1)
-      .map(inst => getComponentName(inst) || UNKNOWN);
-    var ownerInfo = []
-      .concat(
-        // If the parent and child instances have a common owner ancestor, start
-        // with that -- otherwise we just start with the parent's owners.
-        deepestCommon !== -1
-          ? getComponentName(childOwners[deepestCommon]) || UNKNOWN
-          : [],
-        ancestorOwnerNames,
-        ancestorTag,
-        // If we're warning about an invalid (non-parent) ancestry, add '...'
-        isParent ? [] : ['...'],
-        childOwnerNames,
-        childTag,
-      )
-      .join(' > ');
-
-    return ownerInfo;
-  };
-
   var didWarn = {};
 
-  validateDOMNesting = function(
-    childTag,
-    childText,
-    childInstance,
-    ancestorInfo,
-  ) {
+  validateDOMNesting = function(childTag, childText, ancestorInfo) {
     ancestorInfo = ancestorInfo || emptyAncestorInfo;
     var parentInfo = ancestorInfo.current;
     var parentTag = parentInfo && parentInfo.tag;
@@ -507,24 +433,8 @@ if (__DEV__) {
       return;
     }
 
-    var ancestorInstance = invalidParentOrAncestor.instance;
     var ancestorTag = invalidParentOrAncestor.tag;
-    var addendum;
-
-    if (childInstance != null) {
-      addendum =
-        ' See ' +
-        getOwnerInfo(
-          childInstance,
-          childTag,
-          ancestorInstance,
-          ancestorTag,
-          !!invalidParent,
-        ) +
-        '.';
-    } else {
-      addendum = getCurrentFiberStackAddendum();
-    }
+    var addendum = getCurrentFiberStackAddendum();
 
     var warnKey =
       !!invalidParent + '|' + childTag + '|' + ancestorTag + '|' + addendum;
@@ -576,10 +486,8 @@ if (__DEV__) {
     }
   };
 
-  validateDOMNesting.updatedAncestorInfo = updatedAncestorInfo;
-
   // For testing
-  validateDOMNesting.isTagValidInContext = function(tag, ancestorInfo) {
+  isTagValidInContext = function(tag, ancestorInfo) {
     ancestorInfo = ancestorInfo || emptyAncestorInfo;
     var parentInfo = ancestorInfo.current;
     var parentTag = parentInfo && parentInfo.tag;
@@ -589,5 +497,3 @@ if (__DEV__) {
     );
   };
 }
-
-module.exports = validateDOMNesting;
diff --git a/src/renderers/dom/shared/warnValidStyle.js b/src/renderers/dom/shared/warnValidStyle.js
index 89ddcbf0220..52c0ad320ce 100644
--- a/src/renderers/dom/shared/warnValidStyle.js
+++ b/src/renderers/dom/shared/warnValidStyle.js
@@ -11,16 +11,16 @@
 
 'use strict';
 
-var emptyFunction = require('fbjs/lib/emptyFunction');
+import emptyFunction from 'fbjs/lib/emptyFunction';
+import camelizeStyleName from 'fbjs/lib/camelizeStyleName';
+import warning from 'fbjs/lib/warning';
+import {getCurrentFiberOwnerName} from 'ReactDebugCurrentFiber';
 
 var warnValidStyle = emptyFunction;
 
-if (__DEV__) {
-  var camelizeStyleName = require('fbjs/lib/camelizeStyleName');
-  var getComponentName = require('getComponentName');
-  var warning = require('fbjs/lib/warning');
-  var {getCurrentFiberOwnerName} = require('ReactDebugCurrentFiber');
+export default warnValidStyle;
 
+if (__DEV__) {
   // 'msTransform' is correct, but the other prefixes should be capitalized
   var badVendoredStyleNamePattern = /^(?:webkit|moz|o)[A-Z]/;
 
@@ -32,7 +32,7 @@ if (__DEV__) {
   var warnedForNaNValue = false;
   var warnedForInfinityValue = false;
 
-  var warnHyphenatedStyleName = function(name, owner) {
+  var warnHyphenatedStyleName = function(name) {
     if (warnedStyleNames.hasOwnProperty(name) && warnedStyleNames[name]) {
       return;
     }
@@ -43,11 +43,11 @@ if (__DEV__) {
       'Unsupported style property %s. Did you mean %s?%s',
       name,
       camelizeStyleName(name),
-      checkRenderMessage(owner),
+      checkRenderMessage(),
     );
   };
 
-  var warnBadVendoredStyleName = function(name, owner) {
+  var warnBadVendoredStyleName = function(name) {
     if (warnedStyleNames.hasOwnProperty(name) && warnedStyleNames[name]) {
       return;
     }
@@ -58,11 +58,11 @@ if (__DEV__) {
       'Unsupported vendor-prefixed style property %s. Did you mean %s?%s',
       name,
       name.charAt(0).toUpperCase() + name.slice(1),
-      checkRenderMessage(owner),
+      checkRenderMessage(),
     );
   };
 
-  var warnStyleValueWithSemicolon = function(name, value, owner) {
+  var warnStyleValueWithSemicolon = function(name, value) {
     if (warnedStyleValues.hasOwnProperty(value) && warnedStyleValues[value]) {
       return;
     }
@@ -72,13 +72,13 @@ if (__DEV__) {
       false,
       "Style property values shouldn't contain a semicolon.%s " +
         'Try "%s: %s" instead.',
-      checkRenderMessage(owner),
+      checkRenderMessage(),
       name,
       value.replace(badStyleValueWithSemicolonPattern, ''),
     );
   };
 
-  var warnStyleValueIsNaN = function(name, value, owner) {
+  var warnStyleValueIsNaN = function(name, value) {
     if (warnedForNaNValue) {
       return;
     }
@@ -88,11 +88,11 @@ if (__DEV__) {
       false,
       '`NaN` is an invalid value for the `%s` css style property.%s',
       name,
-      checkRenderMessage(owner),
+      checkRenderMessage(),
     );
   };
 
-  var warnStyleValueIsInfinity = function(name, value, owner) {
+  var warnStyleValueIsInfinity = function(name, value) {
     if (warnedForInfinityValue) {
       return;
     }
@@ -102,21 +102,16 @@ if (__DEV__) {
       false,
       '`Infinity` is an invalid value for the `%s` css style property.%s',
       name,
-      checkRenderMessage(owner),
+      checkRenderMessage(),
     );
   };
 
-  var checkRenderMessage = function(owner) {
+  var checkRenderMessage = function() {
     var ownerName;
-    if (owner != null) {
-      // Stack passes the owner manually all the way to CSSPropertyOperations.
-      ownerName = getComponentName(owner);
-    } else {
-      // Fiber doesn't pass it but uses ReactDebugCurrentFiber to track it.
-      // It is only enabled in development and tracks host components too.
-      ownerName = getCurrentFiberOwnerName();
-      // TODO: also report the stack.
-    }
+    // Fiber doesn't pass it but uses ReactDebugCurrentFiber to track it.
+    // It is only enabled in development and tracks host components too.
+    ownerName = getCurrentFiberOwnerName();
+    // TODO: also report the stack.
     if (ownerName) {
       return '\n\nCheck the render method of `' + ownerName + '`.';
     }
@@ -124,27 +119,20 @@ if (__DEV__) {
   };
 
   warnValidStyle = function(name, value, component) {
-    var owner;
-    if (component) {
-      // TODO: this only works with Stack. Seems like we need to add unit tests?
-      owner = component._currentElement._owner;
-    }
     if (name.indexOf('-') > -1) {
-      warnHyphenatedStyleName(name, owner);
+      warnHyphenatedStyleName(name);
     } else if (badVendoredStyleNamePattern.test(name)) {
-      warnBadVendoredStyleName(name, owner);
+      warnBadVendoredStyleName(name);
     } else if (badStyleValueWithSemicolonPattern.test(value)) {
-      warnStyleValueWithSemicolon(name, value, owner);
+      warnStyleValueWithSemicolon(name, value);
     }
 
     if (typeof value === 'number') {
       if (isNaN(value)) {
-        warnStyleValueIsNaN(name, value, owner);
+        warnStyleValueIsNaN(name, value);
       } else if (!isFinite(value)) {
-        warnStyleValueIsInfinity(name, value, owner);
+        warnStyleValueIsInfinity(name, value);
       }
     }
   };
 }
-
-module.exports = warnValidStyle;
diff --git a/src/renderers/dom/shared/wrappers/__tests__/ReactDOMInput-test.js b/src/renderers/dom/shared/wrappers/__tests__/ReactDOMInput-test.js
index b90923c7721..6048875a5af 100644
--- a/src/renderers/dom/shared/wrappers/__tests__/ReactDOMInput-test.js
+++ b/src/renderers/dom/shared/wrappers/__tests__/ReactDOMInput-test.js
@@ -17,7 +17,6 @@ describe('ReactDOMInput', () => {
   var React;
   var ReactDOM;
   var ReactDOMServer;
-  var ReactDOMFeatureFlags;
   var ReactTestUtils;
   var inputValueTracking;
 
@@ -37,7 +36,6 @@ describe('ReactDOMInput', () => {
     React = require('react');
     ReactDOM = require('react-dom');
     ReactDOMServer = require('react-dom/server');
-    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
     ReactTestUtils = require('react-dom/test-utils');
     // TODO: can we express this test with only public API?
     inputValueTracking = require('inputValueTracking');
@@ -1189,7 +1187,6 @@ describe('ReactDOMInput', () => {
       <input value="0" type="range" min="0" max="100" step="1" />,
     );
     expect(log).toEqual([
-      ...(ReactDOMFeatureFlags.useFiber ? [] : ['set data-reactroot']),
       'set type',
       'set step',
       'set min',
@@ -1253,9 +1250,6 @@ describe('ReactDOMInput', () => {
       <input type="date" defaultValue="1980-01-01" />,
     );
     expect(log).toEqual([
-      ...(ReactDOMFeatureFlags.useFiber
-        ? []
-        : ['node.setAttribute("data-reactroot", "")']),
       'node.setAttribute("type", "date")',
       'node.setAttribute("value", "1980-01-01")',
       'node.value = ""',
diff --git a/src/renderers/dom/shared/wrappers/__tests__/ReactDOMOption-test.js b/src/renderers/dom/shared/wrappers/__tests__/ReactDOMOption-test.js
index 7d0dda61f06..73c9e41afd2 100644
--- a/src/renderers/dom/shared/wrappers/__tests__/ReactDOMOption-test.js
+++ b/src/renderers/dom/shared/wrappers/__tests__/ReactDOMOption-test.js
@@ -18,13 +18,11 @@ describe('ReactDOMOption', () => {
 
   var React;
   var ReactDOM;
-  var ReactDOMFeatureFlags;
   var ReactTestUtils;
 
   beforeEach(() => {
     React = require('react');
     ReactDOM = require('react-dom');
-    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
     ReactTestUtils = require('react-dom/test-utils');
   });
 
@@ -47,11 +45,9 @@ describe('ReactDOMOption', () => {
     expectDev(
       normalizeCodeLocInfo(console.error.calls.argsFor(0)[0]),
     ).toContain(
-      ReactDOMFeatureFlags.useFiber
-        ? '<div> cannot appear as a child of <option>.\n' +
-            '    in div (at **)\n' +
-            '    in option (at **)'
-        : 'Only strings and numbers are supported as <option> children.',
+      '<div> cannot appear as a child of <option>.\n' +
+        '    in div (at **)\n' +
+        '    in option (at **)',
     );
   });
 
diff --git a/src/renderers/dom/stack/client/DOMChildrenOperations.js b/src/renderers/dom/stack/client/DOMChildrenOperations.js
deleted file mode 100644
index b7e4e1e105d..00000000000
--- a/src/renderers/dom/stack/client/DOMChildrenOperations.js
+++ /dev/null
@@ -1,250 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule DOMChildrenOperations
- */
-
-'use strict';
-
-var DOMLazyTree = require('DOMLazyTree');
-var Danger = require('Danger');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactInstrumentation = require('ReactInstrumentation');
-
-var createMicrosoftUnsafeLocalFunction = require('createMicrosoftUnsafeLocalFunction');
-var setInnerHTML = require('setInnerHTML');
-var setTextContent = require('setTextContent');
-
-function getNodeAfter(parentNode, node) {
-  // Special case for text components, which return [open, close] comments
-  // from getHostNode.
-  if (Array.isArray(node)) {
-    node = node[1];
-  }
-  return node ? node.nextSibling : parentNode.firstChild;
-}
-
-/**
- * Inserts `childNode` as a child of `parentNode` at the `index`.
- *
- * @param {DOMElement} parentNode Parent node in which to insert.
- * @param {DOMElement} childNode Child node to insert.
- * @param {number} index Index at which to insert the child.
- * @internal
- */
-var insertChildAt = createMicrosoftUnsafeLocalFunction(function(
-  parentNode,
-  childNode,
-  referenceNode,
-) {
-  // We rely exclusively on `insertBefore(node, null)` instead of also using
-  // `appendChild(node)`. (Using `undefined` is not allowed by all browsers so
-  // we are careful to use `null`.)
-  parentNode.insertBefore(childNode, referenceNode);
-});
-
-function insertLazyTreeChildAt(parentNode, childTree, referenceNode) {
-  DOMLazyTree.insertTreeBefore(parentNode, childTree, referenceNode);
-}
-
-function moveChild(parentNode, childNode, referenceNode) {
-  if (Array.isArray(childNode)) {
-    moveDelimitedText(parentNode, childNode[0], childNode[1], referenceNode);
-  } else {
-    insertChildAt(parentNode, childNode, referenceNode);
-  }
-}
-
-function removeChild(parentNode, childNode) {
-  if (Array.isArray(childNode)) {
-    var closingComment = childNode[1];
-    childNode = childNode[0];
-    removeDelimitedText(parentNode, childNode, closingComment);
-    parentNode.removeChild(closingComment);
-  }
-  parentNode.removeChild(childNode);
-}
-
-function moveDelimitedText(
-  parentNode,
-  openingComment,
-  closingComment,
-  referenceNode,
-) {
-  var node = openingComment;
-  while (true) {
-    var nextNode = node.nextSibling;
-    insertChildAt(parentNode, node, referenceNode);
-    if (node === closingComment) {
-      break;
-    }
-    node = nextNode;
-  }
-}
-
-function removeDelimitedText(parentNode, startNode, closingComment) {
-  while (true) {
-    var node = startNode.nextSibling;
-    if (node === closingComment) {
-      // The closing comment is removed by ReactMultiChild.
-      break;
-    } else {
-      parentNode.removeChild(node);
-    }
-  }
-}
-
-function replaceDelimitedText(openingComment, closingComment, stringText) {
-  var parentNode = openingComment.parentNode;
-  var nodeAfterComment = openingComment.nextSibling;
-  if (nodeAfterComment === closingComment) {
-    // There are no text nodes between the opening and closing comments; insert
-    // a new one if stringText isn't empty.
-    if (stringText) {
-      insertChildAt(
-        parentNode,
-        document.createTextNode(stringText),
-        nodeAfterComment,
-      );
-    }
-  } else {
-    if (stringText) {
-      // Set the text content of the first node after the opening comment, and
-      // remove all following nodes up until the closing comment.
-      setTextContent(nodeAfterComment, stringText);
-      removeDelimitedText(parentNode, nodeAfterComment, closingComment);
-    } else {
-      removeDelimitedText(parentNode, openingComment, closingComment);
-    }
-  }
-
-  if (__DEV__) {
-    ReactInstrumentation.debugTool.onHostOperation({
-      instanceID: ReactDOMComponentTree.getInstanceFromNode(openingComment)
-        ._debugID,
-      type: 'replace text',
-      payload: stringText,
-    });
-  }
-}
-
-var dangerouslyReplaceNodeWithMarkup = Danger.dangerouslyReplaceNodeWithMarkup;
-if (__DEV__) {
-  dangerouslyReplaceNodeWithMarkup = function(oldChild, markup, prevInstance) {
-    Danger.dangerouslyReplaceNodeWithMarkup(oldChild, markup);
-    if (prevInstance._debugID !== 0) {
-      ReactInstrumentation.debugTool.onHostOperation({
-        instanceID: prevInstance._debugID,
-        type: 'replace with',
-        payload: markup.toString(),
-      });
-    } else {
-      var nextInstance = ReactDOMComponentTree.getInstanceFromNode(markup.node);
-      if (nextInstance._debugID !== 0) {
-        ReactInstrumentation.debugTool.onHostOperation({
-          instanceID: nextInstance._debugID,
-          type: 'mount',
-          payload: markup.toString(),
-        });
-      }
-    }
-  };
-}
-
-/**
- * Operations for updating with DOM children.
- */
-var DOMChildrenOperations = {
-  dangerouslyReplaceNodeWithMarkup: dangerouslyReplaceNodeWithMarkup,
-
-  replaceDelimitedText: replaceDelimitedText,
-
-  /**
-   * Updates a component's children by processing a series of updates. The
-   * update configurations are each expected to have a `parentNode` property.
-   *
-   * @param {array<object>} updates List of update configurations.
-   * @internal
-   */
-  processUpdates: function(parentNode, updates) {
-    if (__DEV__) {
-      var parentNodeDebugID = ReactDOMComponentTree.getInstanceFromNode(
-        parentNode,
-      )._debugID;
-    }
-
-    for (var k = 0; k < updates.length; k++) {
-      var update = updates[k];
-      switch (update.type) {
-        case 'INSERT_MARKUP':
-          insertLazyTreeChildAt(
-            parentNode,
-            update.content,
-            getNodeAfter(parentNode, update.afterNode),
-          );
-          if (__DEV__) {
-            ReactInstrumentation.debugTool.onHostOperation({
-              instanceID: parentNodeDebugID,
-              type: 'insert child',
-              payload: {
-                toIndex: update.toIndex,
-                content: update.content.toString(),
-              },
-            });
-          }
-          break;
-        case 'MOVE_EXISTING':
-          moveChild(
-            parentNode,
-            update.fromNode,
-            getNodeAfter(parentNode, update.afterNode),
-          );
-          if (__DEV__) {
-            ReactInstrumentation.debugTool.onHostOperation({
-              instanceID: parentNodeDebugID,
-              type: 'move child',
-              payload: {fromIndex: update.fromIndex, toIndex: update.toIndex},
-            });
-          }
-          break;
-        case 'SET_MARKUP':
-          setInnerHTML(parentNode, update.content);
-          if (__DEV__) {
-            ReactInstrumentation.debugTool.onHostOperation({
-              instanceID: parentNodeDebugID,
-              type: 'replace children',
-              payload: update.content.toString(),
-            });
-          }
-          break;
-        case 'TEXT_CONTENT':
-          setTextContent(parentNode, update.content);
-          if (__DEV__) {
-            ReactInstrumentation.debugTool.onHostOperation({
-              instanceID: parentNodeDebugID,
-              type: 'replace text',
-              payload: update.content.toString(),
-            });
-          }
-          break;
-        case 'REMOVE_NODE':
-          removeChild(parentNode, update.fromNode);
-          if (__DEV__) {
-            ReactInstrumentation.debugTool.onHostOperation({
-              instanceID: parentNodeDebugID,
-              type: 'remove child',
-              payload: {fromIndex: update.fromIndex},
-            });
-          }
-          break;
-      }
-    }
-  },
-};
-
-module.exports = DOMChildrenOperations;
diff --git a/src/renderers/dom/stack/client/DOMLazyTree.js b/src/renderers/dom/stack/client/DOMLazyTree.js
deleted file mode 100644
index 8a398a4cd59..00000000000
--- a/src/renderers/dom/stack/client/DOMLazyTree.js
+++ /dev/null
@@ -1,130 +0,0 @@
-/**
- * Copyright 2015-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule DOMLazyTree
- */
-
-'use strict';
-
-var Namespaces = require('DOMNamespaces').Namespaces;
-var setInnerHTML = require('setInnerHTML');
-var {DOCUMENT_FRAGMENT_NODE, ELEMENT_NODE} = require('HTMLNodeType');
-var createMicrosoftUnsafeLocalFunction = require('createMicrosoftUnsafeLocalFunction');
-var setTextContent = require('setTextContent');
-
-/**
- * In IE (8-11) and Edge, appending nodes with no children is dramatically
- * faster than appending a full subtree, so we essentially queue up the
- * .appendChild calls here and apply them so each node is added to its parent
- * before any children are added.
- *
- * In other browsers, doing so is slower or neutral compared to the other order
- * (in Firefox, twice as slow) so we only do this inversion in IE.
- *
- * See https://github.com/spicyj/innerhtml-vs-createelement-vs-clonenode.
- */
-var enableLazy =
-  (typeof document !== 'undefined' &&
-    typeof document.documentMode === 'number') ||
-  (typeof navigator !== 'undefined' &&
-    typeof navigator.userAgent === 'string' &&
-    /\bEdge\/\d/.test(navigator.userAgent));
-
-function insertTreeChildren(tree) {
-  if (!enableLazy) {
-    return;
-  }
-  var node = tree.node;
-  var children = tree.children;
-  if (children.length) {
-    for (var i = 0; i < children.length; i++) {
-      insertTreeBefore(node, children[i], null);
-    }
-  } else if (tree.html != null) {
-    setInnerHTML(node, tree.html);
-  } else if (tree.text != null) {
-    setTextContent(node, tree.text);
-  }
-}
-
-var insertTreeBefore = createMicrosoftUnsafeLocalFunction(function(
-  parentNode,
-  tree,
-  referenceNode,
-) {
-  // DocumentFragments aren't actually part of the DOM after insertion so
-  // appending children won't update the DOM. We need to ensure the fragment
-  // is properly populated first, breaking out of our lazy approach for just
-  // this level. Also, some <object> plugins (like Flash Player) will read
-  // <param> nodes immediately upon insertion into the DOM, so <object>
-  // must also be populated prior to insertion into the DOM.
-  if (
-    tree.node.nodeType === DOCUMENT_FRAGMENT_NODE ||
-    (tree.node.nodeType === ELEMENT_NODE &&
-      tree.node.nodeName.toLowerCase() === 'object' &&
-      (tree.node.namespaceURI == null ||
-        tree.node.namespaceURI === Namespaces.html))
-  ) {
-    insertTreeChildren(tree);
-    parentNode.insertBefore(tree.node, referenceNode);
-  } else {
-    parentNode.insertBefore(tree.node, referenceNode);
-    insertTreeChildren(tree);
-  }
-});
-
-function replaceChildWithTree(oldNode, newTree) {
-  oldNode.parentNode.replaceChild(newTree.node, oldNode);
-  insertTreeChildren(newTree);
-}
-
-function queueChild(parentTree, childTree) {
-  if (enableLazy) {
-    parentTree.children.push(childTree);
-  } else {
-    parentTree.node.appendChild(childTree.node);
-  }
-}
-
-function queueHTML(tree, html) {
-  if (enableLazy) {
-    tree.html = html;
-  } else {
-    setInnerHTML(tree.node, html);
-  }
-}
-
-function queueText(tree, text) {
-  if (enableLazy) {
-    tree.text = text;
-  } else {
-    setTextContent(tree.node, text);
-  }
-}
-
-function toString() {
-  return this.node.nodeName;
-}
-
-function DOMLazyTree(node) {
-  return {
-    node: node,
-    children: [],
-    html: null,
-    text: null,
-    toString,
-  };
-}
-
-DOMLazyTree.insertTreeBefore = insertTreeBefore;
-DOMLazyTree.replaceChildWithTree = replaceChildWithTree;
-DOMLazyTree.queueChild = queueChild;
-DOMLazyTree.queueHTML = queueHTML;
-DOMLazyTree.queueText = queueText;
-
-module.exports = DOMLazyTree;
diff --git a/src/renderers/dom/stack/client/Danger.js b/src/renderers/dom/stack/client/Danger.js
deleted file mode 100644
index 77542e52c88..00000000000
--- a/src/renderers/dom/stack/client/Danger.js
+++ /dev/null
@@ -1,56 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule Danger
- */
-
-'use strict';
-
-var DOMLazyTree = require('DOMLazyTree');
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
-
-var createNodesFromMarkup = require('fbjs/lib/createNodesFromMarkup');
-var emptyFunction = require('fbjs/lib/emptyFunction');
-var invariant = require('fbjs/lib/invariant');
-
-var Danger = {
-  /**
-   * Replaces a node with a string of markup at its current position within its
-   * parent. The markup must render into a single root node.
-   *
-   * @param {DOMElement} oldChild Child node to replace.
-   * @param {string} markup Markup to render in place of the child node.
-   * @internal
-   */
-  dangerouslyReplaceNodeWithMarkup: function(oldChild, markup) {
-    invariant(
-      ExecutionEnvironment.canUseDOM,
-      'dangerouslyReplaceNodeWithMarkup(...): Cannot render markup in a ' +
-        'worker thread. Make sure `window` and `document` are available ' +
-        'globally before requiring React when unit testing or use ' +
-        'ReactDOMServer.renderToString() for server rendering.',
-    );
-    invariant(markup, 'dangerouslyReplaceNodeWithMarkup(...): Missing markup.');
-    invariant(
-      oldChild.nodeName !== 'HTML',
-      'dangerouslyReplaceNodeWithMarkup(...): Cannot replace markup of the ' +
-        '<html> node. This is because browser quirks make this unreliable ' +
-        'and/or slow. If you want to render to the root you must use ' +
-        'server rendering. See ReactDOMServer.renderToString().',
-    );
-
-    if (typeof markup === 'string') {
-      var newChild = createNodesFromMarkup(markup, emptyFunction)[0];
-      oldChild.parentNode.replaceChild(newChild, oldChild);
-    } else {
-      DOMLazyTree.replaceChildWithTree(oldChild, markup);
-    }
-  },
-};
-
-module.exports = Danger;
diff --git a/src/renderers/dom/stack/client/ReactComponentBrowserEnvironment.js b/src/renderers/dom/stack/client/ReactComponentBrowserEnvironment.js
deleted file mode 100644
index fe874cdc6c4..00000000000
--- a/src/renderers/dom/stack/client/ReactComponentBrowserEnvironment.js
+++ /dev/null
@@ -1,28 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactComponentBrowserEnvironment
- */
-
-'use strict';
-
-var DOMChildrenOperations = require('DOMChildrenOperations');
-var ReactDOMIDOperations = require('ReactDOMIDOperations');
-
-/**
- * Abstracts away all functionality of the reconciler that requires knowledge of
- * the browser context. TODO: These callers should be refactored to avoid the
- * need for this injection.
- */
-var ReactComponentBrowserEnvironment = {
-  processChildrenUpdates: ReactDOMIDOperations.dangerouslyProcessChildrenUpdates,
-
-  replaceNodeWithMarkup: DOMChildrenOperations.dangerouslyReplaceNodeWithMarkup,
-};
-
-module.exports = ReactComponentBrowserEnvironment;
diff --git a/src/renderers/dom/stack/client/ReactDOMComponent.js b/src/renderers/dom/stack/client/ReactDOMComponent.js
deleted file mode 100644
index 8f20ebb8913..00000000000
--- a/src/renderers/dom/stack/client/ReactDOMComponent.js
+++ /dev/null
@@ -1,1197 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMComponent
- */
-
-'use strict';
-
-var AutoFocusUtils = require('AutoFocusUtils');
-var CSSPropertyOperations = require('CSSPropertyOperations');
-var DOMLazyTree = require('DOMLazyTree');
-var Namespaces = require('DOMNamespaces').Namespaces;
-var DOMMarkupOperations = require('DOMMarkupOperations');
-var DOMProperty = require('DOMProperty');
-var DOMPropertyOperations = require('DOMPropertyOperations');
-var EventPluginRegistry = require('EventPluginRegistry');
-var ReactBrowserEventEmitter = require('ReactBrowserEventEmitter');
-var ReactDOMComponentFlags = require('ReactDOMComponentFlags');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactDOMInput = require('ReactDOMInput');
-var ReactDOMOption = require('ReactDOMOption');
-var ReactDOMSelect = require('ReactDOMSelect');
-var ReactDOMTextarea = require('ReactDOMTextarea');
-var ReactInstrumentation = require('ReactInstrumentation');
-var ReactMultiChild = require('ReactMultiChild');
-var ReactServerRenderingTransaction = require('ReactServerRenderingTransaction');
-var {DOCUMENT_FRAGMENT_NODE} = require('HTMLNodeType');
-
-var dangerousStyleValue = require('dangerousStyleValue');
-var emptyFunction = require('fbjs/lib/emptyFunction');
-var escapeTextContentForBrowser = require('escapeTextContentForBrowser');
-var hyphenateStyleName = require('fbjs/lib/hyphenateStyleName');
-var inputValueTracking = require('inputValueTracking');
-var invariant = require('fbjs/lib/invariant');
-var isCustomComponent = require('isCustomComponent');
-var memoizeStringOnly = require('fbjs/lib/memoizeStringOnly');
-var omittedCloseTags = require('omittedCloseTags');
-var validateDOMNesting = require('validateDOMNesting');
-var voidElementTags = require('voidElementTags');
-var warnValidStyle = require('warnValidStyle');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
-var didWarnShadyDOM = false;
-
-var Flags = ReactDOMComponentFlags;
-var getNode = ReactDOMComponentTree.getNodeFromInstance;
-var listenTo = ReactBrowserEventEmitter.listenTo;
-var registrationNameModules = EventPluginRegistry.registrationNameModules;
-
-// For quickly matching children type, to test if can be treated as content.
-var CONTENT_TYPES = {string: true, number: true};
-
-var STYLE = 'style';
-var HTML = '__html';
-
-function getDeclarationErrorAddendum(internalInstance) {
-  if (internalInstance) {
-    var owner = internalInstance._currentElement._owner || null;
-    if (owner) {
-      var name = owner.getName();
-      if (name) {
-        return '\n\nThis DOM node was rendered by `' + name + '`.';
-      }
-    }
-  }
-  return '';
-}
-
-/**
- * @param {object} component
- * @param {?object} props
- */
-function assertValidProps(component, props) {
-  if (!props) {
-    return;
-  }
-  // Note the use of `==` which checks for null or undefined.
-  if (voidElementTags[component._tag]) {
-    invariant(
-      props.children == null && props.dangerouslySetInnerHTML == null,
-      '%s is a void element tag and must neither have `children` nor ' +
-        'use `dangerouslySetInnerHTML`.%s',
-      component._tag,
-      getDeclarationErrorAddendum(component),
-    );
-  }
-  if (props.dangerouslySetInnerHTML != null) {
-    invariant(
-      props.children == null,
-      'Can only set one of `children` or `props.dangerouslySetInnerHTML`.',
-    );
-    invariant(
-      typeof props.dangerouslySetInnerHTML === 'object' &&
-        HTML in props.dangerouslySetInnerHTML,
-      '`props.dangerouslySetInnerHTML` must be in the form `{__html: ...}`. ' +
-        'Please visit https://fb.me/react-invariant-dangerously-set-inner-html ' +
-        'for more information.',
-    );
-  }
-  if (__DEV__) {
-    warning(
-      props.suppressContentEditableWarning ||
-        !props.contentEditable ||
-        props.children == null,
-      'A component is `contentEditable` and contains `children` managed by ' +
-        'React. It is now your responsibility to guarantee that none of ' +
-        'those nodes are unexpectedly modified or duplicated. This is ' +
-        'probably not intentional.',
-    );
-  }
-  invariant(
-    props.style == null || typeof props.style === 'object',
-    'The `style` prop expects a mapping from style properties to values, ' +
-      "not a string. For example, style={{marginRight: spacing + 'em'}} when " +
-      'using JSX.%s',
-    getDeclarationErrorAddendum(component),
-  );
-}
-
-function ensureListeningTo(inst, registrationName, transaction) {
-  if (transaction instanceof ReactServerRenderingTransaction) {
-    return;
-  }
-  var containerInfo = inst._hostContainerInfo;
-  var isDocumentFragment =
-    containerInfo._node &&
-    containerInfo._node.nodeType === DOCUMENT_FRAGMENT_NODE;
-  var doc = isDocumentFragment
-    ? containerInfo._node
-    : containerInfo._ownerDocument;
-  listenTo(registrationName, doc);
-}
-
-function inputPostMount() {
-  var inst = this;
-  ReactDOMInput.postMountWrapper(inst);
-}
-
-function textareaPostMount() {
-  var inst = this;
-  ReactDOMTextarea.postMountWrapper(inst);
-}
-
-function optionPostMount() {
-  var inst = this;
-  ReactDOMOption.postMountWrapper(inst);
-}
-
-var processStyleName = memoizeStringOnly(function(styleName) {
-  return hyphenateStyleName(styleName);
-});
-
-function createMarkupForStyles(styles, component) {
-  var serialized = '';
-  var delimiter = '';
-  for (var styleName in styles) {
-    if (!styles.hasOwnProperty(styleName)) {
-      continue;
-    }
-    var isCustomProperty = styleName.indexOf('--') === 0;
-    var styleValue = styles[styleName];
-    if (__DEV__) {
-      if (!isCustomProperty) {
-        warnValidStyle(styleName, styleValue, component);
-      }
-    }
-    if (styleValue != null) {
-      serialized += delimiter + processStyleName(styleName) + ':';
-      serialized += dangerousStyleValue(
-        styleName,
-        styleValue,
-        isCustomProperty,
-      );
-
-      delimiter = ';';
-    }
-  }
-  return serialized || null;
-}
-
-var setAndValidateContentChildDev = emptyFunction;
-if (__DEV__) {
-  setAndValidateContentChildDev = function(content) {
-    var hasExistingContent = this._contentDebugID != null;
-    var debugID = this._debugID;
-    // This ID represents the inlined child that has no backing instance:
-    var contentDebugID = -debugID;
-
-    if (content == null) {
-      if (hasExistingContent) {
-        ReactInstrumentation.debugTool.onUnmountComponent(this._contentDebugID);
-      }
-      this._contentDebugID = null;
-      return;
-    }
-
-    validateDOMNesting(null, '' + content, this, this._ancestorInfo);
-    this._contentDebugID = contentDebugID;
-    if (hasExistingContent) {
-      ReactInstrumentation.debugTool.onBeforeUpdateComponent(
-        contentDebugID,
-        content,
-      );
-      ReactInstrumentation.debugTool.onUpdateComponent(contentDebugID);
-    } else {
-      ReactInstrumentation.debugTool.onBeforeMountComponent(
-        contentDebugID,
-        content,
-        debugID,
-      );
-      ReactInstrumentation.debugTool.onMountComponent(contentDebugID);
-      ReactInstrumentation.debugTool.onSetChildren(debugID, [contentDebugID]);
-    }
-  };
-}
-
-// There are so many media events, it makes sense to just
-// maintain a list rather than create a `trapBubbledEvent` for each
-var mediaEvents = {
-  topAbort: 'abort',
-  topCanPlay: 'canplay',
-  topCanPlayThrough: 'canplaythrough',
-  topDurationChange: 'durationchange',
-  topEmptied: 'emptied',
-  topEncrypted: 'encrypted',
-  topEnded: 'ended',
-  topError: 'error',
-  topLoadedData: 'loadeddata',
-  topLoadedMetadata: 'loadedmetadata',
-  topLoadStart: 'loadstart',
-  topPause: 'pause',
-  topPlay: 'play',
-  topPlaying: 'playing',
-  topProgress: 'progress',
-  topRateChange: 'ratechange',
-  topSeeked: 'seeked',
-  topSeeking: 'seeking',
-  topStalled: 'stalled',
-  topSuspend: 'suspend',
-  topTimeUpdate: 'timeupdate',
-  topVolumeChange: 'volumechange',
-  topWaiting: 'waiting',
-};
-
-function trackInputValue() {
-  inputValueTracking.track(getNode(this));
-}
-
-function trapClickOnNonInteractiveElement() {
-  // Mobile Safari does not fire properly bubble click events on
-  // non-interactive elements, which means delegated click listeners do not
-  // fire. The workaround for this bug involves attaching an empty click
-  // listener on the target node.
-  // http://www.quirksmode.org/blog/archives/2010/09/click_event_del.html
-  // Just set it using the onclick property so that we don't have to manage any
-  // bookkeeping for it. Not sure if we need to clear it when the listener is
-  // removed.
-  // TODO: Only do this for the relevant Safaris maybe?
-  var node = getNode(this);
-  node.onclick = emptyFunction;
-}
-
-function trapBubbledEventsLocal() {
-  var inst = this;
-  // If a component renders to null or if another component fatals and causes
-  // the state of the tree to be corrupted, `node` here can be null.
-  invariant(inst._rootNodeID, 'Must be mounted to trap events');
-  var node = getNode(inst);
-  invariant(node, 'trapBubbledEvent(...): Requires node to be rendered.');
-
-  switch (inst._tag) {
-    case 'iframe':
-    case 'object':
-      inst._wrapperState.listeners = [
-        ReactBrowserEventEmitter.trapBubbledEvent('topLoad', 'load', node),
-      ];
-      break;
-    case 'video':
-    case 'audio':
-      inst._wrapperState.listeners = [];
-      // Create listener for each media event
-      for (var event in mediaEvents) {
-        if (mediaEvents.hasOwnProperty(event)) {
-          inst._wrapperState.listeners.push(
-            ReactBrowserEventEmitter.trapBubbledEvent(
-              event,
-              mediaEvents[event],
-              node,
-            ),
-          );
-        }
-      }
-      break;
-    case 'source':
-      inst._wrapperState.listeners = [
-        ReactBrowserEventEmitter.trapBubbledEvent('topError', 'error', node),
-      ];
-      break;
-    case 'img':
-    case 'image':
-      inst._wrapperState.listeners = [
-        ReactBrowserEventEmitter.trapBubbledEvent('topError', 'error', node),
-        ReactBrowserEventEmitter.trapBubbledEvent('topLoad', 'load', node),
-      ];
-      break;
-    case 'form':
-      inst._wrapperState.listeners = [
-        ReactBrowserEventEmitter.trapBubbledEvent('topReset', 'reset', node),
-        ReactBrowserEventEmitter.trapBubbledEvent('topSubmit', 'submit', node),
-      ];
-      break;
-    case 'input':
-    case 'select':
-    case 'textarea':
-      inst._wrapperState.listeners = [
-        ReactBrowserEventEmitter.trapBubbledEvent(
-          'topInvalid',
-          'invalid',
-          node,
-        ),
-      ];
-      break;
-    case 'details':
-      inst._wrapperState.listeners = [
-        ReactBrowserEventEmitter.trapBubbledEvent('topToggle', 'toggle', node),
-      ];
-      break;
-  }
-}
-
-function postUpdateSelectWrapper() {
-  ReactDOMSelect.postUpdateWrapper(this);
-}
-
-var newlineEatingTags = {
-  listing: true,
-  pre: true,
-  textarea: true,
-};
-
-// We accept any tag to be rendered but since this gets injected into arbitrary
-// HTML, we want to make sure that it's a safe tag.
-// http://www.w3.org/TR/REC-xml/#NT-Name
-
-var VALID_TAG_REGEX = /^[a-zA-Z][a-zA-Z:_\.\-\d]*$/; // Simplified subset
-var validatedTagCache = {};
-
-function validateDangerousTag(tag) {
-  if (!validatedTagCache.hasOwnProperty(tag)) {
-    invariant(VALID_TAG_REGEX.test(tag), 'Invalid tag: %s', tag);
-    validatedTagCache[tag] = true;
-  }
-}
-
-var globalIdCounter = 1;
-var warnedUnknownTags = {
-  // Chrome is the only major browser not shipping <time>. But as of July
-  // 2017 it intends to ship it due to widespread usage. We intentionally
-  // *don't* warn for <time> even if it's unrecognized by Chrome because
-  // it soon will be, and many apps have been using it anyway.
-  time: true,
-};
-
-/**
- * Creates a new React class that is idempotent and capable of containing other
- * React components. It accepts event listeners and DOM properties that are
- * valid according to `DOMProperty`.
- *
- *  - Event listeners: `onClick`, `onMouseDown`, etc.
- *  - DOM properties: `className`, `name`, `title`, etc.
- *
- * The `style` property functions differently from the DOM API. It accepts an
- * object mapping of style properties to values.
- *
- * @constructor ReactDOMComponent
- * @extends ReactMultiChild
- */
-function ReactDOMComponent(element) {
-  var tag = element.type;
-  this._currentElement = element;
-  this._tag = tag.toLowerCase();
-  this._namespaceURI = null;
-  this._renderedChildren = null;
-  this._hostNode = null;
-  this._hostParent = null;
-  this._rootNodeID = 0;
-  this._domID = 0;
-  this._hostContainerInfo = null;
-  this._wrapperState = null;
-  this._topLevelWrapper = null;
-  this._flags = 0;
-  if (__DEV__) {
-    this._ancestorInfo = null;
-    setAndValidateContentChildDev.call(this, null);
-  }
-}
-
-ReactDOMComponent.displayName = 'ReactDOMComponent';
-
-ReactDOMComponent.Mixin = {
-  /**
-   * Generates root tag markup then recurses. This method has side effects and
-   * is not idempotent.
-   *
-   * @internal
-   * @param {ReactReconcileTransaction|ReactServerRenderingTransaction} transaction
-   * @param {?ReactDOMComponent} the parent component instance
-   * @param {?object} info about the host container
-   * @param {object} context
-   * @return {string} The computed markup.
-   */
-  mountComponent: function(
-    transaction,
-    hostParent,
-    hostContainerInfo,
-    context,
-  ) {
-    this._rootNodeID = globalIdCounter++;
-    this._domID = hostContainerInfo._idCounter++;
-    this._hostParent = hostParent;
-    this._hostContainerInfo = hostContainerInfo;
-
-    var props = this._currentElement.props;
-
-    switch (this._tag) {
-      case 'audio':
-      case 'form':
-      case 'iframe':
-      case 'img':
-      case 'image':
-      case 'link':
-      case 'object':
-      case 'source':
-      case 'video':
-      case 'details':
-        this._wrapperState = {
-          listeners: null,
-        };
-        transaction.getReactMountReady().enqueue(trapBubbledEventsLocal, this);
-        break;
-      case 'input':
-        ReactDOMInput.mountWrapper(this, props, hostParent);
-        props = ReactDOMInput.getHostProps(this, props);
-        transaction.getReactMountReady().enqueue(trackInputValue, this);
-        transaction.getReactMountReady().enqueue(trapBubbledEventsLocal, this);
-        // For controlled components we always need to ensure we're listening
-        // to onChange. Even if there is no listener.
-        ensureListeningTo(this, 'onChange', transaction);
-        break;
-      case 'option':
-        ReactDOMOption.mountWrapper(this, props, hostParent);
-        props = ReactDOMOption.getHostProps(this, props);
-        break;
-      case 'select':
-        ReactDOMSelect.mountWrapper(this, props, hostParent);
-        props = ReactDOMSelect.getHostProps(this, props);
-        transaction.getReactMountReady().enqueue(trapBubbledEventsLocal, this);
-        // For controlled components we always need to ensure we're listening
-        // to onChange. Even if there is no listener.
-        ensureListeningTo(this, 'onChange', transaction);
-        break;
-      case 'textarea':
-        ReactDOMTextarea.mountWrapper(this, props, hostParent);
-        props = ReactDOMTextarea.getHostProps(this, props);
-        transaction.getReactMountReady().enqueue(trackInputValue, this);
-        transaction.getReactMountReady().enqueue(trapBubbledEventsLocal, this);
-        // For controlled components we always need to ensure we're listening
-        // to onChange. Even if there is no listener.
-        ensureListeningTo(this, 'onChange', transaction);
-        break;
-    }
-
-    assertValidProps(this, props);
-
-    if (__DEV__) {
-      var isCustomComponentTag = isCustomComponent(this._tag, props);
-    }
-    // We create tags in the namespace of their parent container, except HTML
-    // tags get no namespace.
-    var namespaceURI;
-    var parentTag;
-    if (hostParent != null) {
-      namespaceURI = hostParent._namespaceURI;
-      parentTag = hostParent._tag;
-    } else if (hostContainerInfo._tag) {
-      namespaceURI = hostContainerInfo._namespaceURI;
-      parentTag = hostContainerInfo._tag;
-    }
-    if (
-      namespaceURI == null ||
-      (namespaceURI === Namespaces.svg && parentTag === 'foreignobject')
-    ) {
-      namespaceURI = Namespaces.html;
-    }
-    if (namespaceURI === Namespaces.html) {
-      if (__DEV__) {
-        warning(
-          isCustomComponentTag || this._tag === this._currentElement.type,
-          '<%s /> is using uppercase HTML. Always use lowercase HTML tags ' +
-            'in React.',
-          this._currentElement.type,
-        );
-      }
-      if (this._tag === 'svg') {
-        namespaceURI = Namespaces.svg;
-      } else if (this._tag === 'math') {
-        namespaceURI = Namespaces.mathml;
-      }
-    }
-    this._namespaceURI = namespaceURI;
-
-    if (__DEV__) {
-      var parentInfo;
-      if (hostParent != null) {
-        parentInfo = hostParent._ancestorInfo;
-      } else if (hostContainerInfo._tag) {
-        parentInfo = hostContainerInfo._ancestorInfo;
-      }
-      if (parentInfo) {
-        // parentInfo should always be present except for the top-level
-        // component when server rendering
-        validateDOMNesting(this._tag, null, this, parentInfo);
-      }
-      this._ancestorInfo = validateDOMNesting.updatedAncestorInfo(
-        parentInfo,
-        this._tag,
-        this,
-      );
-    }
-
-    var mountImage;
-    var type = this._currentElement.type;
-    if (transaction.useCreateElement) {
-      var ownerDocument = hostContainerInfo._ownerDocument;
-      var el;
-      if (namespaceURI === Namespaces.html) {
-        if (this._tag === 'script') {
-          // Create the script via .innerHTML so its "parser-inserted" flag is
-          // set to true and it does not execute
-          var div = ownerDocument.createElement('div');
-          div.innerHTML = `<${type}></${type}>`;
-          el = div.removeChild(div.firstChild);
-        } else if (props.is) {
-          el = ownerDocument.createElement(type, {is: props.is});
-        } else {
-          // Separate else branch instead of using `props.is || undefined` above because of a Firefox bug.
-          // See discussion in https://github.com/facebook/react/pull/6896
-          // and discussion in https://bugzilla.mozilla.org/show_bug.cgi?id=1276240
-          el = ownerDocument.createElement(type);
-        }
-      } else {
-        el = ownerDocument.createElementNS(namespaceURI, type);
-      }
-      if (__DEV__) {
-        if (isCustomComponentTag && !didWarnShadyDOM && el.shadyRoot) {
-          var owner = this._currentElement._owner;
-          var name = (owner && owner.getName()) || 'A component';
-          warning(
-            false,
-            '%s is using shady DOM. Using shady DOM with React can ' +
-              'cause things to break subtly.',
-            name,
-          );
-          didWarnShadyDOM = true;
-        }
-        if (this._namespaceURI === Namespaces.html) {
-          if (
-            !isCustomComponentTag &&
-            Object.prototype.toString.call(el) ===
-              '[object HTMLUnknownElement]' &&
-            !Object.prototype.hasOwnProperty.call(warnedUnknownTags, this._tag)
-          ) {
-            warnedUnknownTags[this._tag] = true;
-            warning(
-              false,
-              'The tag <%s> is unrecognized in this browser. ' +
-                'If you meant to render a React component, start its name with ' +
-                'an uppercase letter.',
-              this._tag,
-            );
-          }
-        }
-      }
-      ReactDOMComponentTree.precacheNode(this, el);
-      this._flags |= Flags.hasCachedChildNodes;
-      if (!this._hostParent) {
-        DOMPropertyOperations.setAttributeForRoot(el);
-      }
-      this._updateDOMProperties(null, props, transaction, isCustomComponentTag);
-      var lazyTree = DOMLazyTree(el);
-      this._createInitialChildren(transaction, props, context, lazyTree);
-      mountImage = lazyTree;
-    } else {
-      validateDangerousTag(this._tag);
-      var tagOpen = this._createOpenTagMarkupAndPutListeners(
-        transaction,
-        props,
-      );
-      var tagContent = this._createContentMarkup(transaction, props, context);
-      if (!tagContent && omittedCloseTags[this._tag]) {
-        mountImage = tagOpen + '/>';
-      } else {
-        mountImage = tagOpen + '>' + tagContent + '</' + type + '>';
-      }
-    }
-
-    switch (this._tag) {
-      case 'input':
-        transaction.getReactMountReady().enqueue(inputPostMount, this);
-        if (props.autoFocus) {
-          transaction
-            .getReactMountReady()
-            .enqueue(AutoFocusUtils.focusDOMComponent, this);
-        }
-        break;
-      case 'textarea':
-        transaction.getReactMountReady().enqueue(textareaPostMount, this);
-        if (props.autoFocus) {
-          transaction
-            .getReactMountReady()
-            .enqueue(AutoFocusUtils.focusDOMComponent, this);
-        }
-        break;
-      case 'select':
-        if (props.autoFocus) {
-          transaction
-            .getReactMountReady()
-            .enqueue(AutoFocusUtils.focusDOMComponent, this);
-        }
-        break;
-      case 'button':
-        if (props.autoFocus) {
-          transaction
-            .getReactMountReady()
-            .enqueue(AutoFocusUtils.focusDOMComponent, this);
-        }
-        break;
-      case 'option':
-        transaction.getReactMountReady().enqueue(optionPostMount, this);
-        break;
-      default:
-        if (typeof props.onClick === 'function') {
-          transaction
-            .getReactMountReady()
-            .enqueue(trapClickOnNonInteractiveElement, this);
-        }
-        break;
-    }
-
-    return mountImage;
-  },
-
-  /**
-   * Creates markup for the open tag and all attributes.
-   *
-   * This method has side effects because events get registered.
-   *
-   * Iterating over object properties is faster than iterating over arrays.
-   * @see http://jsperf.com/obj-vs-arr-iteration
-   *
-   * @private
-   * @param {ReactReconcileTransaction|ReactServerRenderingTransaction} transaction
-   * @param {object} props
-   * @return {string} Markup of opening tag.
-   */
-  _createOpenTagMarkupAndPutListeners: function(transaction, props) {
-    var ret = '<' + this._currentElement.type;
-
-    for (var propKey in props) {
-      if (!props.hasOwnProperty(propKey)) {
-        continue;
-      }
-      var propValue = props[propKey];
-      if (propValue == null) {
-        continue;
-      }
-      if (registrationNameModules.hasOwnProperty(propKey)) {
-        if (propValue) {
-          ensureListeningTo(this, propKey, transaction);
-        }
-      } else {
-        if (propKey === STYLE) {
-          if (propValue) {
-            if (__DEV__) {
-              Object.freeze(propValue);
-            }
-          }
-          propValue = createMarkupForStyles(propValue, this);
-        }
-        var markup = null;
-        if (this._tag != null && isCustomComponent(this._tag, props)) {
-          if (!DOMProperty.isReservedProp(propKey)) {
-            markup = DOMMarkupOperations.createMarkupForCustomAttribute(
-              propKey,
-              propValue,
-            );
-          }
-        } else {
-          markup = DOMMarkupOperations.createMarkupForProperty(
-            propKey,
-            propValue,
-          );
-        }
-        if (markup) {
-          ret += ' ' + markup;
-        }
-      }
-    }
-
-    // For static pages, no need to put React ID and checksum. Saves lots of
-    // bytes.
-    if (transaction.renderToStaticMarkup) {
-      return ret;
-    }
-
-    if (!this._hostParent) {
-      ret += ' ' + DOMMarkupOperations.createMarkupForRoot();
-    }
-    ret += ' ' + DOMMarkupOperations.createMarkupForID(this._domID);
-    return ret;
-  },
-
-  /**
-   * Creates markup for the content between the tags.
-   *
-   * @private
-   * @param {ReactReconcileTransaction|ReactServerRenderingTransaction} transaction
-   * @param {object} props
-   * @param {object} context
-   * @return {string} Content markup.
-   */
-  _createContentMarkup: function(transaction, props, context) {
-    var ret = '';
-
-    // Intentional use of != to avoid catching zero/false.
-    var innerHTML = props.dangerouslySetInnerHTML;
-    if (innerHTML != null) {
-      if (innerHTML.__html != null) {
-        ret = innerHTML.__html;
-      }
-    } else {
-      var contentToUse = CONTENT_TYPES[typeof props.children]
-        ? props.children
-        : null;
-      var childrenToUse = contentToUse != null ? null : props.children;
-      if (contentToUse != null) {
-        // TODO: Validate that text is allowed as a child of this node
-        ret = escapeTextContentForBrowser(contentToUse);
-        if (__DEV__) {
-          setAndValidateContentChildDev.call(this, contentToUse);
-        }
-      } else if (childrenToUse != null) {
-        var mountImages = this.mountChildren(
-          childrenToUse,
-          transaction,
-          context,
-        );
-        ret = mountImages.join('');
-      }
-    }
-    if (newlineEatingTags[this._tag] && ret.charAt(0) === '\n') {
-      // text/html ignores the first character in these tags if it's a newline
-      // Prefer to break application/xml over text/html (for now) by adding
-      // a newline specifically to get eaten by the parser. (Alternately for
-      // textareas, replacing "^\n" with "\r\n" doesn't get eaten, and the first
-      // \r is normalized out by HTMLTextAreaElement#value.)
-      // See: <http://www.w3.org/TR/html-polyglot/#newlines-in-textarea-and-pre>
-      // See: <http://www.w3.org/TR/html5/syntax.html#element-restrictions>
-      // See: <http://www.w3.org/TR/html5/syntax.html#newlines>
-      // See: Parsing of "textarea" "listing" and "pre" elements
-      //  from <http://www.w3.org/TR/html5/syntax.html#parsing-main-inbody>
-      return '\n' + ret;
-    } else {
-      return ret;
-    }
-  },
-
-  _createInitialChildren: function(transaction, props, context, lazyTree) {
-    // Intentional use of != to avoid catching zero/false.
-    var innerHTML = props.dangerouslySetInnerHTML;
-    if (innerHTML != null) {
-      const innerHTMLContent = innerHTML.__html;
-      if (innerHTMLContent != null && innerHTMLContent !== '') {
-        DOMLazyTree.queueHTML(lazyTree, innerHTMLContent);
-      }
-    } else {
-      var contentToUse = CONTENT_TYPES[typeof props.children]
-        ? props.children
-        : null;
-      var childrenToUse = contentToUse != null ? null : props.children;
-      // TODO: Validate that text is allowed as a child of this node
-      if (contentToUse != null) {
-        // Avoid setting textContent when the text is empty. In IE11 setting
-        // textContent on a text area will cause the placeholder to not
-        // show within the textarea until it has been focused and blurred again.
-        // https://github.com/facebook/react/issues/6731#issuecomment-254874553
-        if (contentToUse !== '') {
-          if (__DEV__) {
-            setAndValidateContentChildDev.call(this, contentToUse);
-          }
-          DOMLazyTree.queueText(lazyTree, contentToUse);
-        }
-      } else if (childrenToUse != null) {
-        var mountImages = this.mountChildren(
-          childrenToUse,
-          transaction,
-          context,
-        );
-        for (var i = 0; i < mountImages.length; i++) {
-          DOMLazyTree.queueChild(lazyTree, mountImages[i]);
-        }
-      }
-    }
-  },
-
-  /**
-   * Receives a next element and updates the component.
-   *
-   * @internal
-   * @param {ReactElement} nextElement
-   * @param {ReactReconcileTransaction|ReactServerRenderingTransaction} transaction
-   * @param {object} context
-   */
-  receiveComponent: function(nextElement, transaction, context) {
-    var prevElement = this._currentElement;
-    this._currentElement = nextElement;
-    this.updateComponent(transaction, prevElement, nextElement, context);
-  },
-
-  /**
-   * Updates a DOM component after it has already been allocated and
-   * attached to the DOM. Reconciles the root DOM node, then recurses.
-   *
-   * @param {ReactReconcileTransaction} transaction
-   * @param {ReactElement} prevElement
-   * @param {ReactElement} nextElement
-   * @internal
-   * @overridable
-   */
-  updateComponent: function(transaction, prevElement, nextElement, context) {
-    var lastProps = prevElement.props;
-    var nextProps = this._currentElement.props;
-
-    switch (this._tag) {
-      case 'input':
-        lastProps = ReactDOMInput.getHostProps(this, lastProps);
-        nextProps = ReactDOMInput.getHostProps(this, nextProps);
-        break;
-      case 'option':
-        lastProps = ReactDOMOption.getHostProps(this, lastProps);
-        nextProps = ReactDOMOption.getHostProps(this, nextProps);
-        break;
-      case 'select':
-        lastProps = ReactDOMSelect.getHostProps(this, lastProps);
-        nextProps = ReactDOMSelect.getHostProps(this, nextProps);
-        break;
-      case 'textarea':
-        lastProps = ReactDOMTextarea.getHostProps(this, lastProps);
-        nextProps = ReactDOMTextarea.getHostProps(this, nextProps);
-        break;
-      default:
-        if (
-          typeof lastProps.onClick !== 'function' &&
-          typeof nextProps.onClick === 'function'
-        ) {
-          transaction
-            .getReactMountReady()
-            .enqueue(trapClickOnNonInteractiveElement, this);
-        }
-        break;
-    }
-
-    assertValidProps(this, nextProps);
-    var isCustomComponentTag = isCustomComponent(this._tag, nextProps);
-    this._updateDOMProperties(
-      lastProps,
-      nextProps,
-      transaction,
-      isCustomComponentTag,
-    );
-    this._updateDOMChildren(lastProps, nextProps, transaction, context);
-
-    switch (this._tag) {
-      case 'input':
-        // Update the wrapper around inputs *after* updating props. This has to
-        // happen after `_updateDOMProperties`. Otherwise HTML5 input validations
-        // raise warnings and prevent the new value from being assigned.
-        ReactDOMInput.updateWrapper(this);
-        // We also check that we haven't missed a value update, such as a
-        // Radio group shifting the checked value to another named radio input.
-        inputValueTracking.updateValueIfChanged(getNode(this));
-        break;
-      case 'textarea':
-        ReactDOMTextarea.updateWrapper(this);
-        break;
-      case 'select':
-        // <select> value update needs to occur after <option> children
-        // reconciliation
-        transaction.getReactMountReady().enqueue(postUpdateSelectWrapper, this);
-        break;
-    }
-  },
-
-  /**
-   * Reconciles the properties by detecting differences in property values and
-   * updating the DOM as necessary. This function is probably the single most
-   * critical path for performance optimization.
-   *
-   * TODO: Benchmark whether checking for changed values in memory actually
-   *       improves performance (especially statically positioned elements).
-   * TODO: Benchmark the effects of putting this at the top since 99% of props
-   *       do not change for a given reconciliation.
-   * TODO: Benchmark areas that can be improved with caching.
-   *
-   * @private
-   * @param {object} lastProps
-   * @param {object} nextProps
-   * @param {?DOMElement} node
-   */
-  _updateDOMProperties: function(
-    lastProps,
-    nextProps,
-    transaction,
-    isCustomComponentTag,
-  ) {
-    var propKey;
-    var styleName;
-    var styleUpdates;
-    for (propKey in lastProps) {
-      if (
-        nextProps.hasOwnProperty(propKey) ||
-        !lastProps.hasOwnProperty(propKey) ||
-        lastProps[propKey] == null
-      ) {
-        continue;
-      }
-      if (propKey === STYLE) {
-        var lastStyle = lastProps[STYLE];
-        for (styleName in lastStyle) {
-          if (lastStyle.hasOwnProperty(styleName)) {
-            styleUpdates = styleUpdates || {};
-            styleUpdates[styleName] = '';
-          }
-        }
-      } else if (registrationNameModules.hasOwnProperty(propKey)) {
-        // Do nothing for event names.
-      } else if (!DOMProperty.isReservedProp(propKey)) {
-        if (isCustomComponent(this._tag, lastProps)) {
-          DOMPropertyOperations.deleteValueForAttribute(getNode(this), propKey);
-        } else {
-          DOMPropertyOperations.deleteValueForProperty(getNode(this), propKey);
-        }
-      }
-    }
-    for (propKey in nextProps) {
-      var nextProp = nextProps[propKey];
-      var lastProp = lastProps != null ? lastProps[propKey] : undefined;
-      if (
-        !nextProps.hasOwnProperty(propKey) ||
-        nextProp === lastProp ||
-        (nextProp == null && lastProp == null)
-      ) {
-        continue;
-      }
-      if (propKey === STYLE) {
-        if (nextProp) {
-          if (__DEV__) {
-            Object.freeze(nextProp);
-          }
-        }
-        if (lastProp) {
-          // Unset styles on `lastProp` but not on `nextProp`.
-          for (styleName in lastProp) {
-            if (
-              lastProp.hasOwnProperty(styleName) &&
-              (!nextProp || !nextProp.hasOwnProperty(styleName))
-            ) {
-              styleUpdates = styleUpdates || {};
-              styleUpdates[styleName] = '';
-            }
-          }
-          // Update styles that changed since `lastProp`.
-          for (styleName in nextProp) {
-            if (
-              nextProp.hasOwnProperty(styleName) &&
-              lastProp[styleName] !== nextProp[styleName]
-            ) {
-              styleUpdates = styleUpdates || {};
-              styleUpdates[styleName] = nextProp[styleName];
-            }
-          }
-        } else {
-          // Relies on `updateStylesByID` not mutating `styleUpdates`.
-          styleUpdates = nextProp;
-        }
-      } else if (registrationNameModules.hasOwnProperty(propKey)) {
-        if (nextProp) {
-          ensureListeningTo(this, propKey, transaction);
-        }
-      } else if (isCustomComponentTag) {
-        if (!DOMProperty.isReservedProp(propKey)) {
-          DOMPropertyOperations.setValueForAttribute(
-            getNode(this),
-            propKey,
-            nextProp,
-          );
-        }
-      } else if (!DOMProperty.isReservedProp(propKey)) {
-        var node = getNode(this);
-        // If we're updating to null or undefined, we should remove the property
-        // from the DOM node instead of inadvertently setting to a string. This
-        // brings us in line with the same behavior we have on initial render.
-        if (nextProp != null) {
-          DOMPropertyOperations.setValueForProperty(node, propKey, nextProp);
-        } else {
-          DOMPropertyOperations.deleteValueForProperty(node, propKey);
-        }
-      }
-    }
-    if (styleUpdates) {
-      if (__DEV__) {
-        ReactInstrumentation.debugTool.onHostOperation({
-          instanceID: this._debugID,
-          type: 'update styles',
-          payload: styleUpdates,
-        });
-      }
-      CSSPropertyOperations.setValueForStyles(
-        getNode(this),
-        styleUpdates,
-        this,
-      );
-    }
-  },
-
-  /**
-   * Reconciles the children with the various properties that affect the
-   * children content.
-   *
-   * @param {object} lastProps
-   * @param {object} nextProps
-   * @param {ReactReconcileTransaction} transaction
-   * @param {object} context
-   */
-  _updateDOMChildren: function(lastProps, nextProps, transaction, context) {
-    var lastContent = CONTENT_TYPES[typeof lastProps.children]
-      ? lastProps.children
-      : null;
-    var nextContent = CONTENT_TYPES[typeof nextProps.children]
-      ? nextProps.children
-      : null;
-
-    var lastHtml =
-      lastProps.dangerouslySetInnerHTML &&
-      lastProps.dangerouslySetInnerHTML.__html;
-    var nextHtml =
-      nextProps.dangerouslySetInnerHTML &&
-      nextProps.dangerouslySetInnerHTML.__html;
-
-    // Note the use of `!=` which checks for null or undefined.
-    var lastChildren = lastContent != null ? null : lastProps.children;
-    var nextChildren = nextContent != null ? null : nextProps.children;
-
-    // If we're switching from children to content/html or vice versa, remove
-    // the old content
-    var lastHasContentOrHtml = lastContent != null || lastHtml != null;
-    var nextHasContentOrHtml = nextContent != null || nextHtml != null;
-    if (lastChildren != null && nextChildren == null) {
-      this.updateChildren(null, transaction, context);
-    } else if (lastHasContentOrHtml && !nextHasContentOrHtml) {
-      this.updateTextContent('');
-      if (__DEV__) {
-        ReactInstrumentation.debugTool.onSetChildren(this._debugID, []);
-      }
-    }
-
-    if (nextContent != null) {
-      if (lastContent !== nextContent) {
-        this.updateTextContent('' + nextContent);
-        if (__DEV__) {
-          setAndValidateContentChildDev.call(this, nextContent);
-        }
-      }
-    } else if (nextHtml != null) {
-      if (lastHtml !== nextHtml) {
-        this.updateMarkup('' + nextHtml);
-      }
-      if (__DEV__) {
-        ReactInstrumentation.debugTool.onSetChildren(this._debugID, []);
-      }
-    } else if (nextChildren != null) {
-      if (__DEV__) {
-        setAndValidateContentChildDev.call(this, null);
-      }
-
-      this.updateChildren(nextChildren, transaction, context);
-    }
-  },
-
-  getHostNode: function() {
-    return getNode(this);
-  },
-
-  /**
-   * Destroys all event registrations for this instance. Does not remove from
-   * the DOM. That must be done by the parent.
-   *
-   * @internal
-   */
-  unmountComponent: function(safely, skipLifecycle) {
-    switch (this._tag) {
-      case 'audio':
-      case 'form':
-      case 'iframe':
-      case 'img':
-      case 'image':
-      case 'link':
-      case 'object':
-      case 'source':
-      case 'video':
-        var listeners = this._wrapperState.listeners;
-        if (listeners) {
-          for (var i = 0; i < listeners.length; i++) {
-            listeners[i].remove();
-          }
-        }
-        break;
-      case 'input':
-      case 'textarea':
-        inputValueTracking.stopTracking(getNode(this));
-        break;
-      case 'html':
-      case 'head':
-      case 'body':
-        /**
-         * Components like <html> <head> and <body> can't be removed or added
-         * easily in a cross-browser way, however it's valuable to be able to
-         * take advantage of React's reconciliation for styling and <title>
-         * management. So we just document it and throw in dangerous cases.
-         */
-        invariant(
-          false,
-          '<%s> tried to unmount. Because of cross-browser quirks it is ' +
-            'impossible to unmount some top-level components (eg <html>, ' +
-            '<head>, and <body>) reliably and efficiently. To fix this, have a ' +
-            'single top-level component that never unmounts render these ' +
-            'elements.',
-          this._tag,
-        );
-        break;
-    }
-
-    this.unmountChildren(safely, skipLifecycle);
-    ReactDOMComponentTree.uncacheNode(this);
-    this._rootNodeID = 0;
-    this._domID = 0;
-    this._wrapperState = null;
-
-    if (__DEV__) {
-      setAndValidateContentChildDev.call(this, null);
-    }
-  },
-
-  restoreControlledState: function() {
-    switch (this._tag) {
-      case 'input':
-        ReactDOMInput.restoreControlledState(this);
-        return;
-      case 'textarea':
-        ReactDOMTextarea.restoreControlledState(this);
-        return;
-      case 'select':
-        ReactDOMSelect.restoreControlledState(this);
-        return;
-    }
-  },
-
-  getPublicInstance: function() {
-    return getNode(this);
-  },
-};
-
-Object.assign(
-  ReactDOMComponent.prototype,
-  ReactDOMComponent.Mixin,
-  ReactMultiChild,
-);
-
-module.exports = ReactDOMComponent;
diff --git a/src/renderers/dom/stack/client/ReactDOMContainerInfo.js b/src/renderers/dom/stack/client/ReactDOMContainerInfo.js
deleted file mode 100644
index 2e525014b46..00000000000
--- a/src/renderers/dom/stack/client/ReactDOMContainerInfo.js
+++ /dev/null
@@ -1,36 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMContainerInfo
- */
-
-'use strict';
-
-var validateDOMNesting = require('validateDOMNesting');
-var {DOCUMENT_NODE} = require('HTMLNodeType');
-
-function ReactDOMContainerInfo(topLevelWrapper, node) {
-  var info = {
-    _topLevelWrapper: topLevelWrapper,
-    _idCounter: 1,
-    _ownerDocument: node
-      ? node.nodeType === DOCUMENT_NODE ? node : node.ownerDocument
-      : null,
-    _node: node,
-    _tag: node ? node.nodeName.toLowerCase() : null,
-    _namespaceURI: node ? node.namespaceURI : null,
-  };
-  if (__DEV__) {
-    info._ancestorInfo = node
-      ? validateDOMNesting.updatedAncestorInfo(null, info._tag, null)
-      : null;
-  }
-  return info;
-}
-
-module.exports = ReactDOMContainerInfo;
diff --git a/src/renderers/dom/stack/client/ReactDOMEmptyComponent.js b/src/renderers/dom/stack/client/ReactDOMEmptyComponent.js
deleted file mode 100644
index bbc63163420..00000000000
--- a/src/renderers/dom/stack/client/ReactDOMEmptyComponent.js
+++ /dev/null
@@ -1,63 +0,0 @@
-/**
- * Copyright 2014-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMEmptyComponent
- */
-
-'use strict';
-
-var DOMLazyTree = require('DOMLazyTree');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-
-var ReactDOMEmptyComponent = function(instantiate) {
-  // ReactCompositeComponent uses this:
-  this._currentElement = null;
-  // ReactDOMComponentTree uses these:
-  this._hostNode = null;
-  this._hostParent = null;
-  this._hostContainerInfo = null;
-  this._domID = 0;
-};
-Object.assign(ReactDOMEmptyComponent.prototype, {
-  mountComponent: function(
-    transaction,
-    hostParent,
-    hostContainerInfo,
-    context,
-  ) {
-    var domID = hostContainerInfo._idCounter++;
-    this._domID = domID;
-    this._hostParent = hostParent;
-    this._hostContainerInfo = hostContainerInfo;
-
-    var nodeValue = ' react-empty: ' + this._domID + ' ';
-    if (transaction.useCreateElement) {
-      var ownerDocument = hostContainerInfo._ownerDocument;
-      var node = ownerDocument.createComment(nodeValue);
-      ReactDOMComponentTree.precacheNode(this, node);
-      return DOMLazyTree(node);
-    } else {
-      if (transaction.renderToStaticMarkup) {
-        // Normally we'd insert a comment node, but since this is a situation
-        // where React won't take over (static pages), we can simply return
-        // nothing.
-        return '';
-      }
-      return '<!--' + nodeValue + '-->';
-    }
-  },
-  receiveComponent: function() {},
-  getHostNode: function() {
-    return ReactDOMComponentTree.getNodeFromInstance(this);
-  },
-  unmountComponent: function() {
-    ReactDOMComponentTree.uncacheNode(this);
-  },
-});
-
-module.exports = ReactDOMEmptyComponent;
diff --git a/src/renderers/dom/stack/client/ReactDOMIDOperations.js b/src/renderers/dom/stack/client/ReactDOMIDOperations.js
deleted file mode 100644
index e24335341d8..00000000000
--- a/src/renderers/dom/stack/client/ReactDOMIDOperations.js
+++ /dev/null
@@ -1,33 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMIDOperations
- */
-
-'use strict';
-
-var DOMChildrenOperations = require('DOMChildrenOperations');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-
-/**
- * Operations used to process updates to DOM nodes.
- */
-var ReactDOMIDOperations = {
-  /**
-   * Updates a component's children by processing a series of updates.
-   *
-   * @param {array<object>} updates List of update configurations.
-   * @internal
-   */
-  dangerouslyProcessChildrenUpdates: function(parentInst, updates) {
-    var node = ReactDOMComponentTree.getNodeFromInstance(parentInst);
-    DOMChildrenOperations.processUpdates(node, updates);
-  },
-};
-
-module.exports = ReactDOMIDOperations;
diff --git a/src/renderers/dom/stack/client/ReactDOMStackInjection.js b/src/renderers/dom/stack/client/ReactDOMStackInjection.js
deleted file mode 100644
index d6a9bcebb9c..00000000000
--- a/src/renderers/dom/stack/client/ReactDOMStackInjection.js
+++ /dev/null
@@ -1,54 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMStackInjection
- */
-
-'use strict';
-
-var ReactComponentEnvironment = require('ReactComponentEnvironment');
-var ReactComponentBrowserEnvironment = require('ReactComponentBrowserEnvironment');
-var ReactDOMComponent = require('ReactDOMComponent');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactDOMEmptyComponent = require('ReactDOMEmptyComponent');
-var ReactDOMTextComponent = require('ReactDOMTextComponent');
-var ReactDefaultBatchingStrategy = require('ReactDefaultBatchingStrategy');
-var ReactEmptyComponent = require('ReactEmptyComponent');
-var ReactGenericBatching = require('ReactGenericBatching');
-var ReactHostComponent = require('ReactHostComponent');
-var ReactReconcileTransaction = require('ReactReconcileTransaction');
-var ReactUpdates = require('ReactUpdates');
-
-var findDOMNode = require('findDOMNode');
-var getHostComponentFromComposite = require('getHostComponentFromComposite');
-
-ReactGenericBatching.injection.injectStackBatchedUpdates(
-  ReactUpdates.batchedUpdates,
-);
-
-ReactHostComponent.injection.injectGenericComponentClass(ReactDOMComponent);
-
-ReactHostComponent.injection.injectTextComponentClass(ReactDOMTextComponent);
-
-ReactEmptyComponent.injection.injectEmptyComponentFactory(function(
-  instantiate,
-) {
-  return new ReactDOMEmptyComponent(instantiate);
-});
-
-ReactUpdates.injection.injectReconcileTransaction(ReactReconcileTransaction);
-ReactUpdates.injection.injectBatchingStrategy(ReactDefaultBatchingStrategy);
-
-ReactComponentEnvironment.injection.injectEnvironment(
-  ReactComponentBrowserEnvironment,
-);
-
-findDOMNode._injectStack(function(inst) {
-  inst = getHostComponentFromComposite(inst);
-  return inst ? ReactDOMComponentTree.getNodeFromInstance(inst) : null;
-});
diff --git a/src/renderers/dom/stack/client/ReactDOMTextComponent.js b/src/renderers/dom/stack/client/ReactDOMTextComponent.js
deleted file mode 100644
index 992a6267754..00000000000
--- a/src/renderers/dom/stack/client/ReactDOMTextComponent.js
+++ /dev/null
@@ -1,187 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMTextComponent
- */
-
-'use strict';
-
-var DOMChildrenOperations = require('DOMChildrenOperations');
-var DOMLazyTree = require('DOMLazyTree');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var {COMMENT_NODE} = require('HTMLNodeType');
-
-var escapeTextContentForBrowser = require('escapeTextContentForBrowser');
-var invariant = require('fbjs/lib/invariant');
-var validateDOMNesting = require('validateDOMNesting');
-
-/**
- * Text nodes violate a couple assumptions that React makes about components:
- *
- *  - When mounting text into the DOM, adjacent text nodes are merged.
- *  - Text nodes cannot be assigned a React root ID.
- *
- * This component is used to wrap strings between comment nodes so that they
- * can undergo the same reconciliation that is applied to elements.
- *
- * TODO: Investigate representing React components in the DOM with text nodes.
- *
- * @class ReactDOMTextComponent
- * @extends ReactComponent
- * @internal
- */
-var ReactDOMTextComponent = function(text) {
-  // TODO: This is really a ReactText (ReactNode), not a ReactElement
-  this._currentElement = text;
-  this._stringText = '' + text;
-  // ReactDOMComponentTree uses these:
-  this._hostNode = null;
-  this._hostParent = null;
-
-  // Properties
-  this._domID = 0;
-  this._mountIndex = 0;
-  this._closingComment = null;
-  this._commentNodes = null;
-};
-
-Object.assign(ReactDOMTextComponent.prototype, {
-  /**
-   * Creates the markup for this text node. This node is not intended to have
-   * any features besides containing text content.
-   *
-   * @param {ReactReconcileTransaction|ReactServerRenderingTransaction} transaction
-   * @return {string} Markup for this text node.
-   * @internal
-   */
-  mountComponent: function(
-    transaction,
-    hostParent,
-    hostContainerInfo,
-    context,
-  ) {
-    if (__DEV__) {
-      var parentInfo;
-      if (hostParent != null) {
-        parentInfo = hostParent._ancestorInfo;
-      } else if (hostContainerInfo != null) {
-        parentInfo = hostContainerInfo._ancestorInfo;
-      }
-      if (parentInfo) {
-        // parentInfo should always be present except for the top-level
-        // component when server rendering
-        validateDOMNesting(null, this._stringText, this, parentInfo);
-      }
-    }
-
-    var domID = hostContainerInfo._idCounter++;
-    var openingValue = ' react-text: ' + domID + ' ';
-    var closingValue = ' /react-text ';
-    this._domID = domID;
-    this._hostParent = hostParent;
-    if (transaction.useCreateElement) {
-      var ownerDocument = hostContainerInfo._ownerDocument;
-      var openingComment = ownerDocument.createComment(openingValue);
-      var closingComment = ownerDocument.createComment(closingValue);
-      var lazyTree = DOMLazyTree(ownerDocument.createDocumentFragment());
-      DOMLazyTree.queueChild(lazyTree, DOMLazyTree(openingComment));
-      if (this._stringText) {
-        DOMLazyTree.queueChild(
-          lazyTree,
-          DOMLazyTree(ownerDocument.createTextNode(this._stringText)),
-        );
-      }
-      DOMLazyTree.queueChild(lazyTree, DOMLazyTree(closingComment));
-      ReactDOMComponentTree.precacheNode(this, openingComment);
-      this._closingComment = closingComment;
-      return lazyTree;
-    } else {
-      var escapedText = escapeTextContentForBrowser(this._stringText);
-
-      if (transaction.renderToStaticMarkup) {
-        // Normally we'd wrap this between comment nodes for the reasons stated
-        // above, but since this is a situation where React won't take over
-        // (static pages), we can simply return the text as it is.
-        return escapedText;
-      }
-
-      return (
-        '<!--' +
-        openingValue +
-        '-->' +
-        escapedText +
-        '<!--' +
-        closingValue +
-        '-->'
-      );
-    }
-  },
-
-  /**
-   * Updates this component by updating the text content.
-   *
-   * @param {ReactText} nextText The next text content
-   * @param {ReactReconcileTransaction} transaction
-   * @internal
-   */
-  receiveComponent: function(nextText, transaction) {
-    if (nextText !== this._currentElement) {
-      this._currentElement = nextText;
-      var nextStringText = '' + nextText;
-      if (nextStringText !== this._stringText) {
-        // TODO: Save this as pending props and use performUpdateIfNecessary
-        // and/or updateComponent to do the actual update for consistency with
-        // other component types?
-        this._stringText = nextStringText;
-        var commentNodes = this.getHostNode();
-        DOMChildrenOperations.replaceDelimitedText(
-          commentNodes[0],
-          commentNodes[1],
-          nextStringText,
-        );
-      }
-    }
-  },
-
-  getHostNode: function() {
-    var hostNode = this._commentNodes;
-    if (hostNode) {
-      return hostNode;
-    }
-    if (!this._closingComment) {
-      var openingComment = ReactDOMComponentTree.getNodeFromInstance(this);
-      var node = openingComment.nextSibling;
-      while (true) {
-        invariant(
-          node != null,
-          'Missing closing comment for text component %s',
-          this._domID,
-        );
-        if (
-          node.nodeType === COMMENT_NODE &&
-          node.nodeValue === ' /react-text '
-        ) {
-          this._closingComment = node;
-          break;
-        }
-        node = node.nextSibling;
-      }
-    }
-    hostNode = [this._hostNode, this._closingComment];
-    this._commentNodes = hostNode;
-    return hostNode;
-  },
-
-  unmountComponent: function() {
-    this._closingComment = null;
-    this._commentNodes = null;
-    ReactDOMComponentTree.uncacheNode(this);
-  },
-});
-
-module.exports = ReactDOMTextComponent;
diff --git a/src/renderers/dom/stack/client/ReactMount.js b/src/renderers/dom/stack/client/ReactMount.js
deleted file mode 100644
index 649efdd2818..00000000000
--- a/src/renderers/dom/stack/client/ReactMount.js
+++ /dev/null
@@ -1,780 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactMount
- */
-
-'use strict';
-
-var DOMLazyTree = require('DOMLazyTree');
-var DOMProperty = require('DOMProperty');
-var React = require('react');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactDOMContainerInfo = require('ReactDOMContainerInfo');
-var ReactInstanceMap = require('ReactInstanceMap');
-var ReactInstrumentation = require('ReactInstrumentation');
-var ReactMarkupChecksum = require('ReactMarkupChecksum');
-var ReactReconciler = require('ReactReconciler');
-var ReactUpdateQueue = require('ReactUpdateQueue');
-var ReactUpdates = require('ReactUpdates');
-var {ReactCurrentOwner} = require('ReactGlobalSharedState');
-
-var getContextForSubtree = require('getContextForSubtree');
-var instantiateReactComponent = require('instantiateReactComponent');
-var invariant = require('fbjs/lib/invariant');
-var setInnerHTML = require('setInnerHTML');
-var shouldUpdateReactComponent = require('shouldUpdateReactComponent');
-var warning = require('fbjs/lib/warning');
-var validateCallback = require('validateCallback');
-var {
-  DOCUMENT_NODE,
-  ELEMENT_NODE,
-  DOCUMENT_FRAGMENT_NODE,
-} = require('HTMLNodeType');
-
-var ATTR_NAME = DOMProperty.ID_ATTRIBUTE_NAME;
-var ROOT_ATTR_NAME = DOMProperty.ROOT_ATTRIBUTE_NAME;
-
-var instancesByReactRootID = {};
-
-/**
- * Finds the index of the first character
- * that's not common between the two given strings.
- *
- * @return {number} the index of the character where the strings diverge
- */
-function firstDifferenceIndex(string1, string2) {
-  var minLen = Math.min(string1.length, string2.length);
-  for (var i = 0; i < minLen; i++) {
-    if (string1.charAt(i) !== string2.charAt(i)) {
-      return i;
-    }
-  }
-  return string1.length === string2.length ? -1 : minLen;
-}
-
-/**
- * @param {DOMElement|DOMDocument} container DOM element that may contain
- * a React component
- * @return {?*} DOM element that may have the reactRoot ID, or null.
- */
-function getReactRootElementInContainer(container) {
-  if (!container) {
-    return null;
-  }
-
-  if (container.nodeType === DOCUMENT_NODE) {
-    return container.documentElement;
-  } else {
-    return container.firstChild;
-  }
-}
-
-function internalGetID(node) {
-  // If node is something like a window, document, or text node, none of
-  // which support attributes or a .getAttribute method, gracefully return
-  // the empty string, as if the attribute were missing.
-  return (node.getAttribute && node.getAttribute(ATTR_NAME)) || '';
-}
-
-/**
- * Mounts this component and inserts it into the DOM.
- *
- * @param {ReactComponent} componentInstance The instance to mount.
- * @param {DOMElement} container DOM element to mount into.
- * @param {ReactReconcileTransaction} transaction
- * @param {boolean} shouldReuseMarkup If true, do not insert markup
- */
-function mountComponentIntoNode(
-  wrapperInstance,
-  container,
-  transaction,
-  shouldReuseMarkup,
-  context,
-) {
-  var markup = ReactReconciler.mountComponent(
-    wrapperInstance,
-    transaction,
-    null,
-    ReactDOMContainerInfo(wrapperInstance, container),
-    context,
-    0 /* parentDebugID */,
-  );
-
-  wrapperInstance._renderedComponent._topLevelWrapper = wrapperInstance;
-  ReactMount._mountImageIntoNode(
-    markup,
-    container,
-    wrapperInstance,
-    shouldReuseMarkup,
-    transaction,
-  );
-}
-
-/**
- * Batched mount.
- *
- * @param {ReactComponent} componentInstance The instance to mount.
- * @param {DOMElement} container DOM element to mount into.
- * @param {boolean} shouldReuseMarkup If true, do not insert markup
- */
-function batchedMountComponentIntoNode(
-  componentInstance,
-  container,
-  shouldReuseMarkup,
-  context,
-) {
-  var transaction = ReactUpdates.ReactReconcileTransaction.getPooled(
-    /* useCreateElement */
-    !shouldReuseMarkup,
-  );
-  transaction.perform(
-    mountComponentIntoNode,
-    null,
-    componentInstance,
-    container,
-    transaction,
-    shouldReuseMarkup,
-    context,
-  );
-  ReactUpdates.ReactReconcileTransaction.release(transaction);
-}
-
-/**
- * Unmounts a component and removes it from the DOM.
- *
- * @param {ReactComponent} instance React component instance.
- * @param {DOMElement} container DOM element to unmount from.
- * @final
- * @internal
- * @see {ReactMount.unmountComponentAtNode}
- */
-function unmountComponentFromNode(instance, container) {
-  if (__DEV__) {
-    ReactInstrumentation.debugTool.onBeginFlush();
-  }
-  ReactReconciler.unmountComponent(
-    instance,
-    false /* safely */,
-    false /* skipLifecycle */,
-  );
-  if (__DEV__) {
-    ReactInstrumentation.debugTool.onEndFlush();
-  }
-
-  if (container.nodeType === DOCUMENT_NODE) {
-    container = container.documentElement;
-  }
-
-  // http://jsperf.com/emptying-a-node
-  while (container.lastChild) {
-    container.removeChild(container.lastChild);
-  }
-}
-
-/**
- * True if the supplied DOM node has a direct React-rendered child that is
- * not a React root element. Useful for warning in `render`,
- * `unmountComponentAtNode`, etc.
- *
- * @param {?DOMElement} node The candidate DOM node.
- * @return {boolean} True if the DOM element contains a direct child that was
- * rendered by React but is not a root element.
- * @internal
- */
-function hasNonRootReactChild(container) {
-  var rootEl = getReactRootElementInContainer(container);
-  if (rootEl) {
-    var inst = ReactDOMComponentTree.getInstanceFromNode(rootEl);
-    return !!(inst && inst._hostParent);
-  }
-}
-
-/**
- * True if the supplied DOM node is a React DOM element and
- * it has been rendered by another copy of React.
- *
- * @param {?DOMElement} node The candidate DOM node.
- * @return {boolean} True if the DOM has been rendered by another copy of React
- * @internal
- */
-function nodeIsRenderedByOtherInstance(container) {
-  var rootEl = getReactRootElementInContainer(container);
-  return !!(rootEl &&
-    isReactNode(rootEl) &&
-    !ReactDOMComponentTree.getInstanceFromNode(rootEl));
-}
-
-/**
- * True if the supplied DOM node is a valid node element.
- *
- * @param {?DOMElement} node The candidate DOM node.
- * @return {boolean} True if the DOM is a valid DOM node.
- * @internal
- */
-function isValidContainer(node) {
-  return !!(node &&
-    (node.nodeType === ELEMENT_NODE ||
-      node.nodeType === DOCUMENT_NODE ||
-      node.nodeType === DOCUMENT_FRAGMENT_NODE));
-}
-
-/**
- * True if the supplied DOM node is a valid React node element.
- *
- * @param {?DOMElement} node The candidate DOM node.
- * @return {boolean} True if the DOM is a valid React DOM node.
- * @internal
- */
-function isReactNode(node) {
-  return (
-    isValidContainer(node) &&
-    (node.hasAttribute(ROOT_ATTR_NAME) || node.hasAttribute(ATTR_NAME))
-  );
-}
-
-function getHostRootInstanceInContainer(container) {
-  var rootEl = getReactRootElementInContainer(container);
-  var prevHostInstance =
-    rootEl && ReactDOMComponentTree.getInstanceFromNode(rootEl);
-  return prevHostInstance && !prevHostInstance._hostParent
-    ? prevHostInstance
-    : null;
-}
-
-function getTopLevelWrapperInContainer(container) {
-  var root = getHostRootInstanceInContainer(container);
-  return root ? root._hostContainerInfo._topLevelWrapper : null;
-}
-
-/**
- * Temporary (?) hack so that we can store all top-level pending updates on
- * composites instead of having to worry about different types of components
- * here.
- */
-var topLevelRootCounter = 1;
-var TopLevelWrapper = function() {
-  this.rootID = topLevelRootCounter++;
-};
-TopLevelWrapper.prototype.isReactComponent = {};
-if (__DEV__) {
-  TopLevelWrapper.displayName = 'TopLevelWrapper';
-}
-TopLevelWrapper.prototype.render = function() {
-  return this.props.child;
-};
-TopLevelWrapper.isReactTopLevelWrapper = true;
-
-/**
- * Mounting is the process of initializing a React component by creating its
- * representative DOM elements and inserting them into a supplied `container`.
- * Any prior content inside `container` is destroyed in the process.
- *
- *   ReactMount.render(
- *     component,
- *     document.getElementById('container')
- *   );
- *
- *   <div id="container">                   <-- Supplied `container`.
- *     <div data-reactid=".3">              <-- Rendered reactRoot of React
- *       // ...                                 component.
- *     </div>
- *   </div>
- *
- * Inside of `container`, the first element rendered is the "reactRoot".
- */
-var ReactMount = {
-  TopLevelWrapper: TopLevelWrapper,
-
-  /**
-   * Used by devtools. The keys are not important.
-   */
-  _instancesByReactRootID: instancesByReactRootID,
-
-  /**
-   * This is a hook provided to support rendering React components while
-   * ensuring that the apparent scroll position of its `container` does not
-   * change.
-   *
-   * @param {DOMElement} container The `container` being rendered into.
-   * @param {function} renderCallback This must be called once to do the render.
-   */
-  scrollMonitor: function(container, renderCallback) {
-    renderCallback();
-  },
-
-  /**
-   * Take a component that's already mounted into the DOM and replace its props
-   * @param {ReactComponent} prevComponent component instance already in the DOM
-   * @param {ReactElement} nextElement component instance to render
-   * @param {DOMElement} container container to render into
-   * @param {?function} callback function triggered on completion
-   */
-  _updateRootComponent: function(
-    prevComponent,
-    nextElement,
-    nextContext,
-    container,
-    callback,
-  ) {
-    ReactMount.scrollMonitor(container, function() {
-      ReactUpdateQueue.enqueueElementInternal(
-        prevComponent,
-        nextElement,
-        nextContext,
-      );
-      if (callback) {
-        ReactUpdateQueue.enqueueCallbackInternal(prevComponent, callback);
-      }
-    });
-
-    return prevComponent;
-  },
-
-  /**
-   * Render a new component into the DOM. Hooked by hooks!
-   *
-   * @param {ReactElement} nextElement element to render
-   * @param {DOMElement} container container to render into
-   * @param {boolean} shouldReuseMarkup if we should skip the markup insertion
-   * @return {ReactComponent} nextComponent
-   */
-  _renderNewRootComponent: function(
-    nextElement,
-    container,
-    shouldReuseMarkup,
-    context,
-    callback,
-  ) {
-    // Various parts of our code (such as ReactCompositeComponent's
-    // _renderValidatedComponent) assume that calls to render aren't nested;
-    // verify that that's the case.
-    warning(
-      ReactCurrentOwner.current == null,
-      '_renderNewRootComponent(): Render methods should be a pure function ' +
-        'of props and state; triggering nested component updates from ' +
-        'render is not allowed. If necessary, trigger nested updates in ' +
-        'componentDidUpdate.\n\nCheck the render method of %s.',
-      (ReactCurrentOwner.current && ReactCurrentOwner.current.getName()) ||
-        'ReactCompositeComponent',
-    );
-
-    invariant(
-      isValidContainer(container),
-      '_registerComponent(...): Target container is not a DOM element.',
-    );
-
-    var componentInstance = instantiateReactComponent(nextElement, false);
-
-    if (callback) {
-      componentInstance._pendingCallbacks = [
-        function() {
-          validateCallback(callback);
-          callback.call(
-            componentInstance._renderedComponent.getPublicInstance(),
-          );
-        },
-      ];
-    }
-
-    // The initial render is synchronous but any updates that happen during
-    // rendering, in componentWillMount or componentDidMount, will be batched
-    // according to the current batching strategy.
-
-    ReactUpdates.batchedUpdates(
-      batchedMountComponentIntoNode,
-      componentInstance,
-      container,
-      shouldReuseMarkup,
-      context,
-    );
-
-    var wrapperID = componentInstance._instance.rootID;
-    instancesByReactRootID[wrapperID] = componentInstance;
-
-    return componentInstance;
-  },
-
-  /**
-   * Renders a React component into the DOM in the supplied `container`.
-   *
-   * If the React component was previously rendered into `container`, this will
-   * perform an update on it and only mutate the DOM as necessary to reflect the
-   * latest React component.
-   *
-   * @param {ReactComponent} parentComponent The conceptual parent of this render tree.
-   * @param {ReactElement} nextElement Component element to render.
-   * @param {DOMElement} container DOM element to render into.
-   * @param {?function} callback function triggered on completion
-   * @return {ReactComponent} Component instance rendered in `container`.
-   */
-  renderSubtreeIntoContainer: function(
-    parentComponent,
-    nextElement,
-    container,
-    callback,
-  ) {
-    invariant(
-      parentComponent != null && ReactInstanceMap.has(parentComponent),
-      'parentComponent must be a valid React Component',
-    );
-    return ReactMount._renderSubtreeIntoContainer(
-      parentComponent,
-      nextElement,
-      container,
-      callback,
-    );
-  },
-
-  _renderSubtreeIntoContainer: function(
-    parentComponent,
-    nextElement,
-    container,
-    callback,
-  ) {
-    callback = callback === undefined ? null : callback;
-    if (__DEV__) {
-      warning(
-        callback === null || typeof callback === 'function',
-        'render(...): Expected the last optional `callback` argument to be a ' +
-          'function. Instead received: %s.',
-        '' + callback,
-      );
-    }
-    if (!React.isValidElement(nextElement)) {
-      if (typeof nextElement === 'string') {
-        invariant(
-          false,
-          'ReactDOM.render(): Invalid component element. Instead of ' +
-            "passing a string like 'div', pass " +
-            "React.createElement('div') or <div />.",
-        );
-      } else if (typeof nextElement === 'function') {
-        invariant(
-          false,
-          'ReactDOM.render(): Invalid component element. Instead of ' +
-            'passing a class like Foo, pass React.createElement(Foo) ' +
-            'or <Foo />.',
-        );
-      } else if (
-        nextElement != null &&
-        typeof nextElement.props !== 'undefined'
-      ) {
-        // Check if it quacks like an element
-        invariant(
-          false,
-          'ReactDOM.render(): Invalid component element. This may be ' +
-            'caused by unintentionally loading two independent copies ' +
-            'of React.',
-        );
-      } else {
-        invariant(false, 'ReactDOM.render(): Invalid component element.');
-      }
-    }
-
-    warning(
-      !container ||
-        !container.tagName ||
-        container.tagName.toUpperCase() !== 'BODY',
-      'render(): Rendering components directly into document.body is ' +
-        'discouraged, since its children are often manipulated by third-party ' +
-        'scripts and browser extensions. This may lead to subtle ' +
-        'reconciliation issues. Try rendering into a container element created ' +
-        'for your app.',
-    );
-
-    var nextWrappedElement = React.createElement(TopLevelWrapper, {
-      child: nextElement,
-    });
-
-    var nextContext = getContextForSubtree(parentComponent);
-    var prevComponent = getTopLevelWrapperInContainer(container);
-
-    if (prevComponent) {
-      var prevWrappedElement = prevComponent._currentElement;
-      var prevElement = prevWrappedElement.props.child;
-      if (shouldUpdateReactComponent(prevElement, nextElement)) {
-        var publicInst = prevComponent._renderedComponent.getPublicInstance();
-        var updatedCallback =
-          callback &&
-          function() {
-            validateCallback(callback);
-            callback.call(publicInst);
-          };
-        ReactMount._updateRootComponent(
-          prevComponent,
-          nextWrappedElement,
-          nextContext,
-          container,
-          updatedCallback,
-        );
-        return publicInst;
-      } else {
-        ReactMount.unmountComponentAtNode(container);
-      }
-    }
-
-    var reactRootElement = getReactRootElementInContainer(container);
-    var containerHasReactMarkup =
-      reactRootElement && !!internalGetID(reactRootElement);
-    var containerHasNonRootReactChild = hasNonRootReactChild(container);
-
-    if (__DEV__) {
-      warning(
-        !containerHasNonRootReactChild,
-        'render(...): Replacing React-rendered children with a new root ' +
-          'component. If you intended to update the children of this node, ' +
-          'you should instead have the existing children update their state ' +
-          'and render the new components instead of calling ReactDOM.render.',
-      );
-
-      if (!containerHasReactMarkup || reactRootElement.nextSibling) {
-        var rootElementSibling = reactRootElement;
-        while (rootElementSibling) {
-          if (internalGetID(rootElementSibling)) {
-            warning(
-              false,
-              'render(): Target node has markup rendered by React, but there ' +
-                'are unrelated nodes as well. This is most commonly caused by ' +
-                'white-space inserted around server-rendered markup.',
-            );
-            break;
-          }
-          rootElementSibling = rootElementSibling.nextSibling;
-        }
-      }
-    }
-
-    var shouldReuseMarkup =
-      containerHasReactMarkup &&
-      !prevComponent &&
-      !containerHasNonRootReactChild;
-    var component = ReactMount._renderNewRootComponent(
-      nextWrappedElement,
-      container,
-      shouldReuseMarkup,
-      nextContext,
-      callback,
-    )._renderedComponent.getPublicInstance();
-    return component;
-  },
-
-  /**
-   * Renders a React component into the DOM in the supplied `container`.
-   * See https://facebook.github.io/react/docs/react-dom.html#render
-   *
-   * If the React component was previously rendered into `container`, this will
-   * perform an update on it and only mutate the DOM as necessary to reflect the
-   * latest React component.
-   *
-   * @param {ReactElement} nextElement Component element to render.
-   * @param {DOMElement} container DOM element to render into.
-   * @param {?function} callback function triggered on completion
-   * @return {ReactComponent} Component instance rendered in `container`.
-   */
-  render: function(nextElement, container, callback) {
-    return ReactMount._renderSubtreeIntoContainer(
-      null,
-      nextElement,
-      container,
-      callback,
-    );
-  },
-
-  /**
-   * Unmounts and destroys the React component rendered in the `container`.
-   * See https://facebook.github.io/react/docs/react-dom.html#unmountcomponentatnode
-   *
-   * @param {DOMElement} container DOM element containing a React component.
-   * @return {boolean} True if a component was found in and unmounted from
-   *                   `container`
-   */
-  unmountComponentAtNode: function(container) {
-    // Various parts of our code (such as ReactCompositeComponent's
-    // _renderValidatedComponent) assume that calls to render aren't nested;
-    // verify that that's the case. (Strictly speaking, unmounting won't cause a
-    // render but we still don't expect to be in a render call here.)
-    warning(
-      ReactCurrentOwner.current == null,
-      'unmountComponentAtNode(): Render methods should be a pure function ' +
-        'of props and state; triggering nested component updates from render ' +
-        'is not allowed. If necessary, trigger nested updates in ' +
-        'componentDidUpdate.\n\nCheck the render method of %s.',
-      (ReactCurrentOwner.current && ReactCurrentOwner.current.getName()) ||
-        'ReactCompositeComponent',
-    );
-
-    invariant(
-      isValidContainer(container),
-      'unmountComponentAtNode(...): Target container is not a DOM element.',
-    );
-
-    if (__DEV__) {
-      warning(
-        !nodeIsRenderedByOtherInstance(container),
-        "unmountComponentAtNode(): The node you're attempting to unmount " +
-          'was rendered by another copy of React.',
-      );
-    }
-
-    var prevComponent = getTopLevelWrapperInContainer(container);
-    if (!prevComponent) {
-      // Check if the node being unmounted was rendered by React, but isn't a
-      // root node.
-      var containerHasNonRootReactChild = hasNonRootReactChild(container);
-
-      // Check if the container itself is a React root node.
-      var isContainerReactRoot =
-        container.nodeType === ELEMENT_NODE &&
-        container.hasAttribute(ROOT_ATTR_NAME);
-
-      if (__DEV__) {
-        warning(
-          !containerHasNonRootReactChild,
-          "unmountComponentAtNode(): The node you're attempting to unmount " +
-            'was rendered by React and is not a top-level container. %s',
-          isContainerReactRoot
-            ? 'You may have accidentally passed in a React root node instead ' +
-                'of its container.'
-            : 'Instead, have the parent component update its state and ' +
-                'rerender in order to remove this component.',
-        );
-      }
-
-      return false;
-    }
-    delete instancesByReactRootID[prevComponent._instance.rootID];
-    ReactUpdates.batchedUpdates(
-      unmountComponentFromNode,
-      prevComponent,
-      container,
-    );
-    return true;
-  },
-
-  _mountImageIntoNode: function(
-    markup,
-    container,
-    instance,
-    shouldReuseMarkup,
-    transaction,
-  ) {
-    invariant(
-      isValidContainer(container),
-      'mountComponentIntoNode(...): Target container is not valid.',
-    );
-
-    if (shouldReuseMarkup) {
-      var rootElement = getReactRootElementInContainer(container);
-      if (ReactMarkupChecksum.canReuseMarkup(markup, rootElement)) {
-        ReactDOMComponentTree.precacheNode(instance, rootElement);
-        return;
-      } else {
-        var checksum = rootElement.getAttribute(
-          ReactMarkupChecksum.CHECKSUM_ATTR_NAME,
-        );
-        rootElement.removeAttribute(ReactMarkupChecksum.CHECKSUM_ATTR_NAME);
-
-        var rootMarkup = rootElement.outerHTML;
-        rootElement.setAttribute(
-          ReactMarkupChecksum.CHECKSUM_ATTR_NAME,
-          checksum,
-        );
-
-        var normalizedMarkup = markup;
-        if (__DEV__) {
-          // because rootMarkup is retrieved from the DOM, various normalizations
-          // will have occurred which will not be present in `markup`. Here,
-          // insert markup into a <div> or <iframe> depending on the container
-          // type to perform the same normalizations before comparing.
-          var normalizer;
-          if (container.nodeType === ELEMENT_NODE) {
-            normalizer = document.createElement('div');
-            normalizer.innerHTML = markup;
-            normalizedMarkup = normalizer.innerHTML;
-          } else {
-            normalizer = document.createElement('iframe');
-            document.body.appendChild(normalizer);
-            normalizer.contentDocument.write(markup);
-            normalizedMarkup =
-              normalizer.contentDocument.documentElement.outerHTML;
-            document.body.removeChild(normalizer);
-          }
-        }
-
-        var diffIndex = firstDifferenceIndex(normalizedMarkup, rootMarkup);
-        var difference =
-          ' (client) ' +
-          normalizedMarkup.substring(diffIndex - 20, diffIndex + 20) +
-          '\n (server) ' +
-          rootMarkup.substring(diffIndex - 20, diffIndex + 20);
-
-        invariant(
-          container.nodeType !== DOCUMENT_NODE,
-          "You're trying to render a component to the document using " +
-            'server rendering but the checksum was invalid. This usually ' +
-            'means you rendered a different component type or props on ' +
-            'the client from the one on the server, or your render() ' +
-            'methods are impure. React cannot handle this case due to ' +
-            'cross-browser quirks by rendering at the document root. You ' +
-            'should look for environment dependent code in your components ' +
-            'and ensure the props are the same client and server side:\n%s',
-          difference,
-        );
-
-        if (__DEV__) {
-          warning(
-            false,
-            'React attempted to reuse markup in a container but the ' +
-              'checksum was invalid. This generally means that you are ' +
-              'using server rendering and the markup generated on the ' +
-              'server was not what the client was expecting. React injected ' +
-              'new markup to compensate which works but you have lost many ' +
-              'of the benefits of server rendering. Instead, figure out ' +
-              'why the markup being generated is different on the client ' +
-              'or server:\n%s',
-            difference,
-          );
-        }
-      }
-    }
-
-    invariant(
-      container.nodeType !== DOCUMENT_NODE,
-      "You're trying to render a component to the document but " +
-        "you didn't use server rendering. We can't do this " +
-        'without using server rendering due to cross-browser quirks. ' +
-        'See ReactDOMServer.renderToString() for server rendering.',
-    );
-
-    if (transaction.useCreateElement) {
-      while (container.lastChild) {
-        container.removeChild(container.lastChild);
-      }
-      DOMLazyTree.insertTreeBefore(container, markup, null);
-    } else {
-      setInnerHTML(container, markup);
-      ReactDOMComponentTree.precacheNode(instance, container.firstChild);
-    }
-
-    if (__DEV__) {
-      var hostNode = ReactDOMComponentTree.getInstanceFromNode(
-        container.firstChild,
-      );
-      if (hostNode._debugID !== 0) {
-        ReactInstrumentation.debugTool.onHostOperation({
-          instanceID: hostNode._debugID,
-          type: 'mount',
-          payload: markup.toString(),
-        });
-      }
-    }
-  },
-};
-
-module.exports = ReactMount;
diff --git a/src/renderers/dom/stack/client/ReactReconcileTransaction.js b/src/renderers/dom/stack/client/ReactReconcileTransaction.js
deleted file mode 100644
index 7047e47fa69..00000000000
--- a/src/renderers/dom/stack/client/ReactReconcileTransaction.js
+++ /dev/null
@@ -1,180 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactReconcileTransaction
- */
-
-'use strict';
-
-var CallbackQueue = require('CallbackQueue');
-var PooledClass = require('PooledClass');
-var ReactBrowserEventEmitter = require('ReactBrowserEventEmitter');
-var ReactInputSelection = require('ReactInputSelection');
-var ReactInstrumentation = require('ReactInstrumentation');
-var Transaction = require('Transaction');
-var ReactUpdateQueue = require('ReactUpdateQueue');
-
-/**
- * Ensures that, when possible, the selection range (currently selected text
- * input) is not disturbed by performing the transaction.
- */
-var SELECTION_RESTORATION = {
-  /**
-   * @return {Selection} Selection information.
-   */
-  initialize: ReactInputSelection.getSelectionInformation,
-  /**
-   * @param {Selection} sel Selection information returned from `initialize`.
-   */
-  close: ReactInputSelection.restoreSelection,
-};
-
-/**
- * Suppresses events (blur/focus) that could be inadvertently dispatched due to
- * high level DOM manipulations (like temporarily removing a text input from the
- * DOM).
- */
-var EVENT_SUPPRESSION = {
-  /**
-   * @return {boolean} The enabled status of `ReactBrowserEventEmitter` before
-   * the reconciliation.
-   */
-  initialize: function() {
-    var currentlyEnabled = ReactBrowserEventEmitter.isEnabled();
-    ReactBrowserEventEmitter.setEnabled(false);
-    return currentlyEnabled;
-  },
-
-  /**
-   * @param {boolean} previouslyEnabled Enabled status of
-   *   `ReactBrowserEventEmitter` before the reconciliation occurred. `close`
-   *   restores the previous value.
-   */
-  close: function(previouslyEnabled) {
-    ReactBrowserEventEmitter.setEnabled(previouslyEnabled);
-  },
-};
-
-/**
- * Provides a queue for collecting `componentDidMount` and
- * `componentDidUpdate` callbacks during the transaction.
- */
-var ON_DOM_READY_QUEUEING = {
-  /**
-   * Initializes the internal `onDOMReady` queue.
-   */
-  initialize: function() {
-    this.reactMountReady.reset();
-  },
-
-  /**
-   * After DOM is flushed, invoke all registered `onDOMReady` callbacks.
-   */
-  close: function() {
-    this.reactMountReady.notifyAll();
-  },
-};
-
-/**
- * Executed within the scope of the `Transaction` instance. Consider these as
- * being member methods, but with an implied ordering while being isolated from
- * each other.
- */
-var TRANSACTION_WRAPPERS = [
-  SELECTION_RESTORATION,
-  EVENT_SUPPRESSION,
-  ON_DOM_READY_QUEUEING,
-];
-
-if (__DEV__) {
-  TRANSACTION_WRAPPERS.push({
-    initialize: ReactInstrumentation.debugTool.onBeginFlush,
-    close: ReactInstrumentation.debugTool.onEndFlush,
-  });
-}
-
-/**
- * Currently:
- * - The order that these are listed in the transaction is critical:
- * - Suppresses events.
- * - Restores selection range.
- *
- * Future:
- * - Restore document/overflow scroll positions that were unintentionally
- *   modified via DOM insertions above the top viewport boundary.
- * - Implement/integrate with customized constraint based layout system and keep
- *   track of which dimensions must be remeasured.
- *
- * @class ReactReconcileTransaction
- */
-function ReactReconcileTransaction(useCreateElement) {
-  this.reinitializeTransaction();
-  // Only server-side rendering really needs this option (see
-  // `ReactServerRendering`), but server-side uses
-  // `ReactServerRenderingTransaction` instead. This option is here so that it's
-  // accessible and defaults to false when `ReactDOMComponent` and
-  // `ReactDOMTextComponent` checks it in `mountComponent`.`
-  this.renderToStaticMarkup = false;
-  this.reactMountReady = CallbackQueue.getPooled();
-  this.useCreateElement = useCreateElement;
-}
-
-var Mixin = {
-  /**
-   * @see Transaction
-   * @abstract
-   * @final
-   * @return {array<object>} List of operation wrap procedures.
-   *   TODO: convert to array<TransactionWrapper>
-   */
-  getTransactionWrappers: function() {
-    return TRANSACTION_WRAPPERS;
-  },
-
-  /**
-   * @return {object} The queue to collect `onDOMReady` callbacks with.
-   */
-  getReactMountReady: function() {
-    return this.reactMountReady;
-  },
-
-  /**
-   * @return {object} The queue to collect React async events.
-   */
-  getUpdateQueue: function() {
-    return ReactUpdateQueue;
-  },
-
-  /**
-   * Save current transaction state -- if the return value from this method is
-   * passed to `rollback`, the transaction will be reset to that state.
-   */
-  checkpoint: function() {
-    // reactMountReady is the our only stateful wrapper
-    return this.reactMountReady.checkpoint();
-  },
-
-  rollback: function(checkpoint) {
-    this.reactMountReady.rollback(checkpoint);
-  },
-
-  /**
-   * `PooledClass` looks for this, and will invoke this before allowing this
-   * instance to be reused.
-   */
-  destructor: function() {
-    CallbackQueue.release(this.reactMountReady);
-    this.reactMountReady = null;
-  },
-};
-
-Object.assign(ReactReconcileTransaction.prototype, Transaction, Mixin);
-
-PooledClass.addPoolingTo(ReactReconcileTransaction);
-
-module.exports = ReactReconcileTransaction;
diff --git a/src/renderers/dom/stack/client/wrappers/ReactDOMInput.js b/src/renderers/dom/stack/client/wrappers/ReactDOMInput.js
deleted file mode 100644
index 8ac425f52ed..00000000000
--- a/src/renderers/dom/stack/client/wrappers/ReactDOMInput.js
+++ /dev/null
@@ -1,339 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMInput
- */
-
-'use strict';
-
-var DOMPropertyOperations = require('DOMPropertyOperations');
-var ReactControlledValuePropTypes = require('ReactControlledValuePropTypes');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-
-var invariant = require('fbjs/lib/invariant');
-var warning = require('fbjs/lib/warning');
-
-if (__DEV__) {
-  var {
-    getStackAddendumByID,
-  } = require('ReactGlobalSharedState').ReactComponentTreeHook;
-}
-
-var didWarnValueDefaultValue = false;
-var didWarnCheckedDefaultChecked = false;
-var didWarnControlledToUncontrolled = false;
-var didWarnUncontrolledToControlled = false;
-
-function isControlled(props) {
-  var usesChecked = props.type === 'checkbox' || props.type === 'radio';
-  return usesChecked ? props.checked != null : props.value != null;
-}
-
-/**
- * Implements an <input> host component that allows setting these optional
- * props: `checked`, `value`, `defaultChecked`, and `defaultValue`.
- *
- * If `checked` or `value` are not supplied (or null/undefined), user actions
- * that affect the checked state or value will trigger updates to the element.
- *
- * If they are supplied (and not null/undefined), the rendered element will not
- * trigger updates to the element. Instead, the props must change in order for
- * the rendered element to be updated.
- *
- * The rendered element will be initialized as unchecked (or `defaultChecked`)
- * with an empty value (or `defaultValue`).
- *
- * @see http://www.w3.org/TR/2012/WD-html5-20121025/the-input-element.html
- */
-var ReactDOMInput = {
-  getHostProps: function(inst, props) {
-    var value = props.value;
-    var checked = props.checked;
-
-    var hostProps = Object.assign(
-      {
-        // Make sure we set .type before any other properties (setting .value
-        // before .type means .value is lost in IE11 and below)
-        type: undefined,
-        // Make sure we set .step before .value (setting .value before .step
-        // means .value is rounded on mount, based upon step precision)
-        step: undefined,
-        // Make sure we set .min & .max before .value (to ensure proper order
-        // in corner cases such as min or max deriving from value, e.g. Issue #7170)
-        min: undefined,
-        max: undefined,
-      },
-      props,
-      {
-        defaultChecked: undefined,
-        defaultValue: undefined,
-        value: value != null ? value : inst._wrapperState.initialValue,
-        checked: checked != null ? checked : inst._wrapperState.initialChecked,
-      },
-    );
-
-    return hostProps;
-  },
-
-  mountWrapper: function(inst, props) {
-    if (__DEV__) {
-      var owner = inst._currentElement._owner;
-      ReactControlledValuePropTypes.checkPropTypes('input', props, () =>
-        getStackAddendumByID(inst._debugID),
-      );
-
-      if (
-        props.checked !== undefined &&
-        props.defaultChecked !== undefined &&
-        !didWarnCheckedDefaultChecked
-      ) {
-        warning(
-          false,
-          '%s contains an input of type %s with both checked and defaultChecked props. ' +
-            'Input elements must be either controlled or uncontrolled ' +
-            '(specify either the checked prop, or the defaultChecked prop, but not ' +
-            'both). Decide between using a controlled or uncontrolled input ' +
-            'element and remove one of these props. More info: ' +
-            'https://fb.me/react-controlled-components',
-          (owner && owner.getName()) || 'A component',
-          props.type,
-        );
-        didWarnCheckedDefaultChecked = true;
-      }
-      if (
-        props.value !== undefined &&
-        props.defaultValue !== undefined &&
-        !didWarnValueDefaultValue
-      ) {
-        warning(
-          false,
-          '%s contains an input of type %s with both value and defaultValue props. ' +
-            'Input elements must be either controlled or uncontrolled ' +
-            '(specify either the value prop, or the defaultValue prop, but not ' +
-            'both). Decide between using a controlled or uncontrolled input ' +
-            'element and remove one of these props. More info: ' +
-            'https://fb.me/react-controlled-components',
-          (owner && owner.getName()) || 'A component',
-          props.type,
-        );
-        didWarnValueDefaultValue = true;
-      }
-    }
-
-    var defaultValue = props.defaultValue;
-    inst._wrapperState = {
-      initialChecked: props.checked != null
-        ? props.checked
-        : props.defaultChecked,
-      initialValue: props.value != null ? props.value : defaultValue,
-      listeners: null,
-      controlled: isControlled(props),
-    };
-  },
-
-  updateWrapper: function(inst) {
-    var props = inst._currentElement.props;
-
-    if (__DEV__) {
-      var controlled = isControlled(props);
-
-      if (
-        !inst._wrapperState.controlled &&
-        controlled &&
-        !didWarnUncontrolledToControlled
-      ) {
-        warning(
-          false,
-          'A component is changing an uncontrolled input of type %s to be controlled. ' +
-            'Input elements should not switch from uncontrolled to controlled (or vice versa). ' +
-            'Decide between using a controlled or uncontrolled input ' +
-            'element for the lifetime of the component. More info: https://fb.me/react-controlled-components%s',
-          props.type,
-          getStackAddendumByID(inst._debugID),
-        );
-        didWarnUncontrolledToControlled = true;
-      }
-      if (
-        inst._wrapperState.controlled &&
-        !controlled &&
-        !didWarnControlledToUncontrolled
-      ) {
-        warning(
-          false,
-          'A component is changing a controlled input of type %s to be uncontrolled. ' +
-            'Input elements should not switch from controlled to uncontrolled (or vice versa). ' +
-            'Decide between using a controlled or uncontrolled input ' +
-            'element for the lifetime of the component. More info: https://fb.me/react-controlled-components%s',
-          props.type,
-          getStackAddendumByID(inst._debugID),
-        );
-        didWarnControlledToUncontrolled = true;
-      }
-    }
-
-    var checked = props.checked;
-    if (checked != null) {
-      DOMPropertyOperations.setValueForProperty(
-        ReactDOMComponentTree.getNodeFromInstance(inst),
-        'checked',
-        checked || false,
-      );
-    }
-
-    var node = ReactDOMComponentTree.getNodeFromInstance(inst);
-    var value = props.value;
-    if (value != null) {
-      if (value === 0 && node.value === '') {
-        node.value = '0';
-        // Note: IE9 reports a number inputs as 'text', so check props instead.
-      } else if (props.type === 'number') {
-        // Simulate `input.valueAsNumber`. IE9 does not support it
-        var valueAsNumber = parseFloat(node.value, 10) || 0;
-
-        if (
-          // eslint-disable-next-line
-          value != valueAsNumber ||
-          // eslint-disable-next-line
-          (value == valueAsNumber && node.value != value)
-        ) {
-          // Cast `value` to a string to ensure the value is set correctly. While
-          // browsers typically do this as necessary, jsdom doesn't.
-          node.value = '' + value;
-        }
-      } else if (node.value !== '' + value) {
-        // Cast `value` to a string to ensure the value is set correctly. While
-        // browsers typically do this as necessary, jsdom doesn't.
-        node.value = '' + value;
-      }
-    } else {
-      if (props.value == null && props.defaultValue != null) {
-        // In Chrome, assigning defaultValue to certain input types triggers input validation.
-        // For number inputs, the display value loses trailing decimal points. For email inputs,
-        // Chrome raises "The specified value <x> is not a valid email address".
-        //
-        // Here we check to see if the defaultValue has actually changed, avoiding these problems
-        // when the user is inputting text
-        //
-        // https://github.com/facebook/react/issues/7253
-        if (node.defaultValue !== '' + props.defaultValue) {
-          node.defaultValue = '' + props.defaultValue;
-        }
-      }
-      if (props.checked == null && props.defaultChecked != null) {
-        node.defaultChecked = !!props.defaultChecked;
-      }
-    }
-  },
-
-  postMountWrapper: function(inst) {
-    var props = inst._currentElement.props;
-
-    // This is in postMount because we need access to the DOM node, which is not
-    // available until after the component has mounted.
-    var node = ReactDOMComponentTree.getNodeFromInstance(inst);
-
-    // Detach value from defaultValue. We won't do anything if we're working on
-    // submit or reset inputs as those values & defaultValues are linked. They
-    // are not resetable nodes so this operation doesn't matter and actually
-    // removes browser-default values (eg "Submit Query") when no value is
-    // provided.
-
-    switch (props.type) {
-      case 'submit':
-      case 'reset':
-        break;
-      case 'color':
-      case 'date':
-      case 'datetime':
-      case 'datetime-local':
-      case 'month':
-      case 'time':
-      case 'week':
-        // This fixes the no-show issue on iOS Safari and Android Chrome:
-        // https://github.com/facebook/react/issues/7233
-        node.value = '';
-        node.value = node.defaultValue;
-        break;
-      default:
-        node.value = node.value;
-        break;
-    }
-
-    // Normally, we'd just do `node.checked = node.checked` upon initial mount, less this bug
-    // this is needed to work around a chrome bug where setting defaultChecked
-    // will sometimes influence the value of checked (even after detachment).
-    // Reference: https://bugs.chromium.org/p/chromium/issues/detail?id=608416
-    // We need to temporarily unset name to avoid disrupting radio button groups.
-    var name = node.name;
-    if (name !== '') {
-      node.name = '';
-    }
-    node.defaultChecked = !node.defaultChecked;
-    node.defaultChecked = !node.defaultChecked;
-    if (name !== '') {
-      node.name = name;
-    }
-  },
-
-  restoreControlledState: function(inst) {
-    if (inst._rootNodeID) {
-      // DOM component is still mounted; update
-      ReactDOMInput.updateWrapper(inst);
-    }
-    var props = inst._currentElement.props;
-    updateNamedCousins(inst, props);
-  },
-};
-
-function updateNamedCousins(thisInstance, props) {
-  var name = props.name;
-  if (props.type === 'radio' && name != null) {
-    var rootNode = ReactDOMComponentTree.getNodeFromInstance(thisInstance);
-    var queryRoot = rootNode;
-
-    while (queryRoot.parentNode) {
-      queryRoot = queryRoot.parentNode;
-    }
-
-    // If `rootNode.form` was non-null, then we could try `form.elements`,
-    // but that sometimes behaves strangely in IE8. We could also try using
-    // `form.getElementsByName`, but that will only return direct children
-    // and won't include inputs that use the HTML5 `form=` attribute. Since
-    // the input might not even be in a form. It might not even be in the
-    // document. Let's just use the local `querySelectorAll` to ensure we don't
-    // miss anything.
-    var group = queryRoot.querySelectorAll(
-      'input[name=' + JSON.stringify('' + name) + '][type="radio"]',
-    );
-
-    for (var i = 0; i < group.length; i++) {
-      var otherNode = group[i];
-      if (otherNode === rootNode || otherNode.form !== rootNode.form) {
-        continue;
-      }
-      // This will throw if radio buttons rendered by different copies of React
-      // and the same name are rendered into the same form (same as #1939).
-      // That's probably okay; we don't support it just as we don't support
-      // mixing React radio buttons with non-React ones.
-      var otherInstance = ReactDOMComponentTree.getInstanceFromNode(otherNode);
-      invariant(
-        otherInstance,
-        'ReactDOMInput: Mixing React and non-React radio inputs with the ' +
-          'same `name` is not supported.',
-      );
-      // If this is a controlled radio button group, forcing the input that
-      // was previously checked to update will cause it to be come re-checked
-      // as appropriate.
-      if (otherInstance._rootNodeID) {
-        ReactDOMInput.updateWrapper(otherInstance);
-      }
-    }
-  }
-}
-
-module.exports = ReactDOMInput;
diff --git a/src/renderers/dom/stack/client/wrappers/ReactDOMOption.js b/src/renderers/dom/stack/client/wrappers/ReactDOMOption.js
deleted file mode 100644
index cc679ebd716..00000000000
--- a/src/renderers/dom/stack/client/wrappers/ReactDOMOption.js
+++ /dev/null
@@ -1,130 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMOption
- */
-
-'use strict';
-
-var React = require('react');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-var ReactDOMSelect = require('ReactDOMSelect');
-
-var warning = require('fbjs/lib/warning');
-var didWarnInvalidOptionChildren = false;
-
-function flattenChildren(children) {
-  var content = '';
-
-  // Flatten children and warn if they aren't strings or numbers;
-  // invalid types are ignored.
-  React.Children.forEach(children, function(child) {
-    if (child == null) {
-      return;
-    }
-    if (typeof child === 'string' || typeof child === 'number') {
-      content += child;
-    } else if (!didWarnInvalidOptionChildren) {
-      didWarnInvalidOptionChildren = true;
-      warning(
-        false,
-        'Only strings and numbers are supported as <option> children.',
-      );
-    }
-  });
-
-  return content;
-}
-
-/**
- * Implements an <option> host component that warns when `selected` is set.
- */
-var ReactDOMOption = {
-  mountWrapper: function(inst, props, hostParent) {
-    // TODO (yungsters): Remove support for `selected` in <option>.
-    if (__DEV__) {
-      warning(
-        props.selected == null,
-        'Use the `defaultValue` or `value` props on <select> instead of ' +
-          'setting `selected` on <option>.',
-      );
-    }
-
-    // Look up whether this option is 'selected'
-    var selectValue = null;
-    if (hostParent != null) {
-      var selectParent = hostParent;
-
-      if (selectParent._tag === 'optgroup') {
-        selectParent = selectParent._hostParent;
-      }
-
-      if (selectParent != null && selectParent._tag === 'select') {
-        selectValue = ReactDOMSelect.getSelectValueContext(selectParent);
-      }
-    }
-
-    // If the value is null (e.g., no specified value or after initial mount)
-    // or missing (e.g., for <datalist>), we don't change props.selected
-    var selected = null;
-    if (selectValue != null) {
-      var value;
-      if (props.value != null) {
-        value = props.value + '';
-      } else {
-        value = flattenChildren(props.children);
-      }
-      selected = false;
-      if (Array.isArray(selectValue)) {
-        // multiple
-        for (var i = 0; i < selectValue.length; i++) {
-          if ('' + selectValue[i] === value) {
-            selected = true;
-            break;
-          }
-        }
-      } else {
-        selected = '' + selectValue === value;
-      }
-    }
-
-    inst._wrapperState = {selected: selected};
-  },
-
-  postMountWrapper: function(inst) {
-    // value="" should make a value attribute (#6219)
-    var props = inst._currentElement.props;
-    if (props.value != null) {
-      var node = ReactDOMComponentTree.getNodeFromInstance(inst);
-      node.setAttribute('value', props.value);
-    }
-  },
-
-  getHostProps: function(inst, props) {
-    var hostProps = Object.assign(
-      {selected: undefined, children: undefined},
-      props,
-    );
-
-    // Read state only from initial mount because <select> updates value
-    // manually; we need the initial state only for server rendering
-    if (inst._wrapperState.selected != null) {
-      hostProps.selected = inst._wrapperState.selected;
-    }
-
-    var content = flattenChildren(props.children);
-
-    if (content) {
-      hostProps.children = content;
-    }
-
-    return hostProps;
-  },
-};
-
-module.exports = ReactDOMOption;
diff --git a/src/renderers/dom/stack/client/wrappers/ReactDOMSelect.js b/src/renderers/dom/stack/client/wrappers/ReactDOMSelect.js
deleted file mode 100644
index 21fea02bb64..00000000000
--- a/src/renderers/dom/stack/client/wrappers/ReactDOMSelect.js
+++ /dev/null
@@ -1,205 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMSelect
- */
-
-'use strict';
-
-var ReactControlledValuePropTypes = require('ReactControlledValuePropTypes');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-
-var warning = require('fbjs/lib/warning');
-
-if (__DEV__) {
-  var {
-    getStackAddendumByID,
-  } = require('ReactGlobalSharedState').ReactComponentTreeHook;
-}
-
-var didWarnValueDefaultValue = false;
-
-function getDeclarationErrorAddendum(owner) {
-  if (owner) {
-    var name = owner.getName();
-    if (name) {
-      return '\n\nCheck the render method of `' + name + '`.';
-    }
-  }
-  return '';
-}
-
-var valuePropNames = ['value', 'defaultValue'];
-
-/**
- * Validation function for `value` and `defaultValue`.
- * @private
- */
-function checkSelectPropTypes(inst, props) {
-  var owner = inst._currentElement._owner;
-  ReactControlledValuePropTypes.checkPropTypes('select', props, () =>
-    getStackAddendumByID(inst._debugID),
-  );
-
-  for (var i = 0; i < valuePropNames.length; i++) {
-    var propName = valuePropNames[i];
-    if (props[propName] == null) {
-      continue;
-    }
-    var isArray = Array.isArray(props[propName]);
-    if (props.multiple && !isArray) {
-      warning(
-        false,
-        'The `%s` prop supplied to <select> must be an array if ' +
-          '`multiple` is true.%s',
-        propName,
-        getDeclarationErrorAddendum(owner),
-      );
-    } else if (!props.multiple && isArray) {
-      warning(
-        false,
-        'The `%s` prop supplied to <select> must be a scalar ' +
-          'value if `multiple` is false.%s',
-        propName,
-        getDeclarationErrorAddendum(owner),
-      );
-    }
-  }
-}
-
-/**
- * @param {ReactDOMComponent} inst
- * @param {boolean} multiple
- * @param {*} propValue A stringable (with `multiple`, a list of stringables).
- * @private
- */
-function updateOptions(inst, multiple, propValue) {
-  var options = ReactDOMComponentTree.getNodeFromInstance(inst).options;
-
-  if (multiple) {
-    let selectedValue = {};
-    for (let i = 0; i < propValue.length; i++) {
-      // Prefix to avoid chaos with special keys.
-      selectedValue['$' + propValue[i]] = true;
-    }
-    for (let i = 0; i < options.length; i++) {
-      var selected = selectedValue.hasOwnProperty('$' + options[i].value);
-      if (options[i].selected !== selected) {
-        options[i].selected = selected;
-      }
-    }
-  } else {
-    // Do not set `select.value` as exact behavior isn't consistent across all
-    // browsers for all cases.
-    let selectedValue = '' + propValue;
-    for (let i = 0; i < options.length; i++) {
-      if (options[i].value === selectedValue) {
-        options[i].selected = true;
-        return;
-      }
-    }
-    if (options.length) {
-      options[0].selected = true;
-    }
-  }
-}
-
-/**
- * Implements a <select> host component that allows optionally setting the
- * props `value` and `defaultValue`. If `multiple` is false, the prop must be a
- * stringable. If `multiple` is true, the prop must be an array of stringables.
- *
- * If `value` is not supplied (or null/undefined), user actions that change the
- * selected option will trigger updates to the rendered options.
- *
- * If it is supplied (and not null/undefined), the rendered options will not
- * update in response to user actions. Instead, the `value` prop must change in
- * order for the rendered options to update.
- *
- * If `defaultValue` is provided, any options with the supplied values will be
- * selected.
- */
-var ReactDOMSelect = {
-  getHostProps: function(inst, props) {
-    return Object.assign({}, props, {
-      value: undefined,
-    });
-  },
-
-  mountWrapper: function(inst, props) {
-    if (__DEV__) {
-      checkSelectPropTypes(inst, props);
-    }
-
-    var value = props.value;
-    inst._wrapperState = {
-      initialValue: value != null ? value : props.defaultValue,
-      listeners: null,
-      wasMultiple: !!props.multiple,
-    };
-
-    if (
-      props.value !== undefined &&
-      props.defaultValue !== undefined &&
-      !didWarnValueDefaultValue
-    ) {
-      warning(
-        false,
-        'Select elements must be either controlled or uncontrolled ' +
-          '(specify either the value prop, or the defaultValue prop, but not ' +
-          'both). Decide between using a controlled or uncontrolled select ' +
-          'element and remove one of these props. More info: ' +
-          'https://fb.me/react-controlled-components',
-      );
-      didWarnValueDefaultValue = true;
-    }
-  },
-
-  getSelectValueContext: function(inst) {
-    // ReactDOMOption looks at this initial value so the initial generated
-    // markup has correct `selected` attributes
-    return inst._wrapperState.initialValue;
-  },
-
-  postUpdateWrapper: function(inst) {
-    var props = inst._currentElement.props;
-
-    // After the initial mount, we control selected-ness manually so don't pass
-    // this value down
-    inst._wrapperState.initialValue = undefined;
-
-    var wasMultiple = inst._wrapperState.wasMultiple;
-    inst._wrapperState.wasMultiple = !!props.multiple;
-
-    var value = props.value;
-    if (value != null) {
-      updateOptions(inst, !!props.multiple, value);
-    } else if (wasMultiple !== !!props.multiple) {
-      // For simplicity, reapply `defaultValue` if `multiple` is toggled.
-      if (props.defaultValue != null) {
-        updateOptions(inst, !!props.multiple, props.defaultValue);
-      } else {
-        // Revert the select back to its default unselected state.
-        updateOptions(inst, !!props.multiple, props.multiple ? [] : '');
-      }
-    }
-  },
-
-  restoreControlledState: function(inst) {
-    if (inst._rootNodeID) {
-      var props = inst._currentElement.props;
-      var value = props.value;
-
-      if (value != null) {
-        updateOptions(inst, !!props.multiple, value);
-      }
-    }
-  },
-};
-
-module.exports = ReactDOMSelect;
diff --git a/src/renderers/dom/stack/client/wrappers/ReactDOMTextarea.js b/src/renderers/dom/stack/client/wrappers/ReactDOMTextarea.js
deleted file mode 100644
index b939d687403..00000000000
--- a/src/renderers/dom/stack/client/wrappers/ReactDOMTextarea.js
+++ /dev/null
@@ -1,174 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDOMTextarea
- */
-
-'use strict';
-
-var ReactControlledValuePropTypes = require('ReactControlledValuePropTypes');
-var ReactDOMComponentTree = require('ReactDOMComponentTree');
-
-var invariant = require('fbjs/lib/invariant');
-var warning = require('fbjs/lib/warning');
-
-if (__DEV__) {
-  var {
-    getStackAddendumByID,
-  } = require('ReactGlobalSharedState').ReactComponentTreeHook;
-}
-
-var didWarnValDefaultVal = false;
-
-/**
- * Implements a <textarea> host component that allows setting `value`, and
- * `defaultValue`. This differs from the traditional DOM API because value is
- * usually set as PCDATA children.
- *
- * If `value` is not supplied (or null/undefined), user actions that affect the
- * value will trigger updates to the element.
- *
- * If `value` is supplied (and not null/undefined), the rendered element will
- * not trigger updates to the element. Instead, the `value` prop must change in
- * order for the rendered element to be updated.
- *
- * The rendered element will be initialized with an empty value, the prop
- * `defaultValue` if specified, or the children content (deprecated).
- */
-var ReactDOMTextarea = {
-  getHostProps: function(inst, props) {
-    invariant(
-      props.dangerouslySetInnerHTML == null,
-      '`dangerouslySetInnerHTML` does not make sense on <textarea>.',
-    );
-
-    // Always set children to the same thing. In IE9, the selection range will
-    // get reset if `textContent` is mutated.  We could add a check in setTextContent
-    // to only set the value if/when the value differs from the node value (which would
-    // completely solve this IE9 bug), but Sebastian+Ben seemed to like this solution.
-    // The value can be a boolean or object so that's why it's forced to be a string.
-    var hostProps = Object.assign({}, props, {
-      value: undefined,
-      defaultValue: undefined,
-      children: '' + inst._wrapperState.initialValue,
-    });
-
-    return hostProps;
-  },
-
-  mountWrapper: function(inst, props) {
-    if (__DEV__) {
-      ReactControlledValuePropTypes.checkPropTypes('textarea', props, () =>
-        getStackAddendumByID(inst._debugID),
-      );
-      if (
-        props.value !== undefined &&
-        props.defaultValue !== undefined &&
-        !didWarnValDefaultVal
-      ) {
-        warning(
-          false,
-          'Textarea elements must be either controlled or uncontrolled ' +
-            '(specify either the value prop, or the defaultValue prop, but not ' +
-            'both). Decide between using a controlled or uncontrolled textarea ' +
-            'and remove one of these props. More info: ' +
-            'https://fb.me/react-controlled-components',
-        );
-        didWarnValDefaultVal = true;
-      }
-    }
-
-    var value = props.value;
-    var initialValue = value;
-
-    // Only bother fetching default value if we're going to use it
-    if (value == null) {
-      var defaultValue = props.defaultValue;
-      // TODO (yungsters): Remove support for children content in <textarea>.
-      var children = props.children;
-      if (children != null) {
-        if (__DEV__) {
-          warning(
-            false,
-            'Use the `defaultValue` or `value` props instead of setting ' +
-              'children on <textarea>.',
-          );
-        }
-        invariant(
-          defaultValue == null,
-          'If you supply `defaultValue` on a <textarea>, do not pass children.',
-        );
-        if (Array.isArray(children)) {
-          invariant(
-            children.length <= 1,
-            '<textarea> can only have at most one child.',
-          );
-          children = children[0];
-        }
-
-        defaultValue = '' + children;
-      }
-      if (defaultValue == null) {
-        defaultValue = '';
-      }
-      initialValue = defaultValue;
-    }
-
-    inst._wrapperState = {
-      initialValue: '' + initialValue,
-      listeners: null,
-    };
-  },
-
-  updateWrapper: function(inst) {
-    var props = inst._currentElement.props;
-
-    var node = ReactDOMComponentTree.getNodeFromInstance(inst);
-    var value = props.value;
-    if (value != null) {
-      // Cast `value` to a string to ensure the value is set correctly. While
-      // browsers typically do this as necessary, jsdom doesn't.
-      var newValue = '' + value;
-
-      // To avoid side effects (such as losing text selection), only set value if changed
-      if (newValue !== node.value) {
-        node.value = newValue;
-      }
-      if (props.defaultValue == null) {
-        node.defaultValue = newValue;
-      }
-    }
-    if (props.defaultValue != null) {
-      node.defaultValue = props.defaultValue;
-    }
-  },
-
-  postMountWrapper: function(inst) {
-    // This is in postMount because we need access to the DOM node, which is not
-    // available until after the component has mounted.
-    var node = ReactDOMComponentTree.getNodeFromInstance(inst);
-    var textContent = node.textContent;
-
-    // Only set node.value if textContent is equal to the expected
-    // initial value. In IE10/IE11 there is a bug where the placeholder attribute
-    // will populate textContent as well.
-    // https://developer.microsoft.com/microsoft-edge/platform/issues/101525/
-    if (textContent === inst._wrapperState.initialValue) {
-      node.value = textContent;
-    }
-  },
-
-  restoreControlledState: function(inst) {
-    if (inst._rootNodeID) {
-      // DOM component is still mounted; update
-      ReactDOMTextarea.updateWrapper(inst);
-    }
-  },
-};
-
-module.exports = ReactDOMTextarea;
diff --git a/src/renderers/dom/stack/server/ReactMarkupChecksum.js b/src/renderers/dom/stack/server/ReactMarkupChecksum.js
deleted file mode 100644
index 09e477c4772..00000000000
--- a/src/renderers/dom/stack/server/ReactMarkupChecksum.js
+++ /dev/null
@@ -1,55 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactMarkupChecksum
- */
-
-'use strict';
-
-var adler32 = require('adler32');
-
-var TAG_END = /\/?>/;
-var COMMENT_START = /^<\!\-\-/;
-
-var ReactMarkupChecksum = {
-  CHECKSUM_ATTR_NAME: 'data-react-checksum',
-
-  /**
-   * @param {string} markup Markup string
-   * @return {string} Markup string with checksum attribute attached
-   */
-  addChecksumToMarkup: function(markup) {
-    var checksum = adler32(markup);
-
-    // Add checksum (handle both parent tags, comments and self-closing tags)
-    if (COMMENT_START.test(markup)) {
-      return markup;
-    } else {
-      return markup.replace(
-        TAG_END,
-        ' ' + ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="' + checksum + '"$&',
-      );
-    }
-  },
-
-  /**
-   * @param {string} markup to use
-   * @param {DOMElement} element root React element
-   * @returns {boolean} whether or not the markup is the same
-   */
-  canReuseMarkup: function(markup, element) {
-    var existingChecksum = element.getAttribute(
-      ReactMarkupChecksum.CHECKSUM_ATTR_NAME,
-    );
-    existingChecksum = existingChecksum && parseInt(existingChecksum, 10);
-    var markupChecksum = adler32(markup);
-    return markupChecksum === existingChecksum;
-  },
-};
-
-module.exports = ReactMarkupChecksum;
diff --git a/src/renderers/dom/stack/server/ReactServerBatchingStrategy.js b/src/renderers/dom/stack/server/ReactServerBatchingStrategy.js
deleted file mode 100644
index 35fa02e57d7..00000000000
--- a/src/renderers/dom/stack/server/ReactServerBatchingStrategy.js
+++ /dev/null
@@ -1,22 +0,0 @@
-/**
- * Copyright 2014-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactServerBatchingStrategy
- */
-
-'use strict';
-
-var ReactServerBatchingStrategy = {
-  isBatchingUpdates: false,
-  batchedUpdates: function(callback) {
-    // Don't do anything here. During the server rendering we don't want to
-    // schedule any updates. We will simply ignore them.
-  },
-};
-
-module.exports = ReactServerBatchingStrategy;
diff --git a/src/renderers/dom/stack/server/ReactServerRendering.js b/src/renderers/dom/stack/server/ReactServerRendering.js
deleted file mode 100644
index c2d54dcf731..00000000000
--- a/src/renderers/dom/stack/server/ReactServerRendering.js
+++ /dev/null
@@ -1,103 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactServerRendering
- */
-'use strict';
-
-var React = require('react');
-var ReactDOMContainerInfo = require('ReactDOMContainerInfo');
-var ReactInstrumentation = require('ReactInstrumentation');
-var ReactMarkupChecksum = require('ReactMarkupChecksum');
-var ReactReconciler = require('ReactReconciler');
-var ReactServerBatchingStrategy = require('ReactServerBatchingStrategy');
-var ReactServerRenderingTransaction = require('ReactServerRenderingTransaction');
-var ReactUpdates = require('ReactUpdates');
-
-var emptyObject = require('fbjs/lib/emptyObject');
-var instantiateReactComponent = require('instantiateReactComponent');
-var invariant = require('fbjs/lib/invariant');
-
-var pendingTransactions = 0;
-
-/**
- * @param {ReactElement} element
- * @return {string} the HTML markup
- */
-function renderToStringImpl(element, makeStaticMarkup) {
-  var transaction;
-  var previousBatchingStrategy;
-  try {
-    previousBatchingStrategy = ReactUpdates.injection.getBatchingStrategy();
-    ReactUpdates.injection.injectBatchingStrategy(ReactServerBatchingStrategy);
-
-    transaction = ReactServerRenderingTransaction.getPooled(makeStaticMarkup);
-
-    pendingTransactions++;
-
-    return transaction.perform(function() {
-      var componentInstance = instantiateReactComponent(element, true);
-      var markup = ReactReconciler.mountComponent(
-        componentInstance,
-        transaction,
-        null,
-        ReactDOMContainerInfo(),
-        emptyObject,
-        0 /* parentDebugID */,
-      );
-      if (__DEV__) {
-        ReactInstrumentation.debugTool.onUnmountComponent(
-          componentInstance._debugID,
-        );
-      }
-      if (!makeStaticMarkup) {
-        markup = ReactMarkupChecksum.addChecksumToMarkup(markup);
-      }
-      return markup;
-    }, null);
-  } finally {
-    pendingTransactions--;
-    ReactServerRenderingTransaction.release(transaction);
-    // Revert to the DOM batching strategy since these two renderers
-    // currently share these stateful modules.
-    if (!pendingTransactions) {
-      ReactUpdates.injection.injectBatchingStrategy(previousBatchingStrategy);
-    }
-  }
-}
-
-/**
- * Render a ReactElement to its initial HTML. This should only be used on the
- * server.
- * See https://facebook.github.io/react/docs/react-dom-server.html#rendertostring
- */
-function renderToString(element) {
-  invariant(
-    React.isValidElement(element),
-    'renderToString(): Invalid component element.',
-  );
-  return renderToStringImpl(element, false);
-}
-
-/**
- * Similar to renderToString, except this doesn't create extra DOM attributes
- * such as data-react-id that React uses internally.
- * See https://facebook.github.io/react/docs/react-dom-server.html#rendertostaticmarkup
- */
-function renderToStaticMarkup(element) {
-  invariant(
-    React.isValidElement(element),
-    'renderToStaticMarkup(): Invalid component element.',
-  );
-  return renderToStringImpl(element, true);
-}
-
-module.exports = {
-  renderToString: renderToString,
-  renderToStaticMarkup: renderToStaticMarkup,
-};
diff --git a/src/renderers/dom/stack/server/ReactServerRenderingTransaction.js b/src/renderers/dom/stack/server/ReactServerRenderingTransaction.js
deleted file mode 100644
index 2fa930cc43d..00000000000
--- a/src/renderers/dom/stack/server/ReactServerRenderingTransaction.js
+++ /dev/null
@@ -1,88 +0,0 @@
-/**
- * Copyright 2014-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactServerRenderingTransaction
- */
-
-'use strict';
-
-var PooledClass = require('PooledClass');
-var Transaction = require('Transaction');
-var ReactInstrumentation = require('ReactInstrumentation');
-var ReactServerUpdateQueue = require('ReactServerUpdateQueue');
-
-/**
- * Executed within the scope of the `Transaction` instance. Consider these as
- * being member methods, but with an implied ordering while being isolated from
- * each other.
- */
-var TRANSACTION_WRAPPERS = [];
-
-if (__DEV__) {
-  TRANSACTION_WRAPPERS.push({
-    initialize: ReactInstrumentation.debugTool.onBeginFlush,
-    close: ReactInstrumentation.debugTool.onEndFlush,
-  });
-}
-
-var noopCallbackQueue = {
-  enqueue: function() {},
-};
-
-/**
- * @class ReactServerRenderingTransaction
- * @param {boolean} renderToStaticMarkup
- */
-function ReactServerRenderingTransaction(renderToStaticMarkup) {
-  this.reinitializeTransaction();
-  this.renderToStaticMarkup = renderToStaticMarkup;
-  this.useCreateElement = false;
-  this.updateQueue = new ReactServerUpdateQueue(this);
-}
-
-var Mixin = {
-  /**
-   * @see Transaction
-   * @abstract
-   * @final
-   * @return {array} Empty list of operation wrap procedures.
-   */
-  getTransactionWrappers: function() {
-    return TRANSACTION_WRAPPERS;
-  },
-
-  /**
-   * @return {object} The queue to collect `onDOMReady` callbacks with.
-   */
-  getReactMountReady: function() {
-    return noopCallbackQueue;
-  },
-
-  /**
-   * @return {object} The queue to collect React async events.
-   */
-  getUpdateQueue: function() {
-    return this.updateQueue;
-  },
-
-  /**
-   * `PooledClass` looks for this, and will invoke this before allowing this
-   * instance to be reused.
-   */
-  destructor: function() {},
-
-  checkpoint: function() {},
-
-  rollback: function() {},
-};
-
-Object.assign(ReactServerRenderingTransaction.prototype, Transaction, Mixin);
-
-PooledClass.addPoolingTo(ReactServerRenderingTransaction);
-
-module.exports = ReactServerRenderingTransaction;
diff --git a/src/renderers/dom/stack/server/ReactServerUpdateQueue.js b/src/renderers/dom/stack/server/ReactServerUpdateQueue.js
deleted file mode 100644
index 35b064f5433..00000000000
--- a/src/renderers/dom/stack/server/ReactServerUpdateQueue.js
+++ /dev/null
@@ -1,152 +0,0 @@
-/**
- * Copyright 2015-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactServerUpdateQueue
- * @flow
- */
-
-'use strict';
-
-var ReactUpdateQueue = require('ReactUpdateQueue');
-
-var warning = require('fbjs/lib/warning');
-
-import type {Transaction} from 'Transaction';
-
-function warnNoop(
-  publicInstance: ReactComponent<any, any, any>,
-  callerName: string,
-) {
-  if (__DEV__) {
-    var constructor = publicInstance.constructor;
-    warning(
-      false,
-      '%s(...): Can only update a mounting component. ' +
-        'This usually means you called %s() outside componentWillMount() on the server. ' +
-        'This is a no-op.\n\nPlease check the code for the %s component.',
-      callerName,
-      callerName,
-      (constructor && (constructor.displayName || constructor.name)) ||
-        'ReactClass',
-    );
-  }
-}
-
-/**
- * This is the update queue used for server rendering.
- * It delegates to ReactUpdateQueue while server rendering is in progress and
- * switches to ReactNoopUpdateQueue after the transaction has completed.
- * @class ReactServerUpdateQueue
- * @param {Transaction} transaction
- */
-class ReactServerUpdateQueue {
-  transaction: Transaction;
-
-  constructor(transaction: Transaction) {
-    this.transaction = transaction;
-  }
-
-  /**
-   * Checks whether or not this composite component is mounted.
-   * @param {ReactClass} publicInstance The instance we want to test.
-   * @return {boolean} True if mounted, false otherwise.
-   * @protected
-   * @final
-   */
-  isMounted(publicInstance: ReactComponent<any, any, any>): boolean {
-    return false;
-  }
-
-  /**
-   * Forces an update. This should only be invoked when it is known with
-   * certainty that we are **not** in a DOM transaction.
-   *
-   * You may want to call this when you know that some deeper aspect of the
-   * component's state has changed but `setState` was not called.
-   *
-   * This will not invoke `shouldComponentUpdate`, but it will invoke
-   * `componentWillUpdate` and `componentDidUpdate`.
-   *
-   * @param {ReactClass} publicInstance The instance that should rerender.
-   * @param {?function} callback Called after component is updated.
-   * @param {?string} Name of the calling function in the public API.
-   * @internal
-   */
-  enqueueForceUpdate(
-    publicInstance: ReactComponent<any, any, any>,
-    callback?: Function,
-    callerName?: string,
-  ) {
-    if (this.transaction.isInTransaction()) {
-      ReactUpdateQueue.enqueueForceUpdate(publicInstance, callback, callerName);
-    } else {
-      warnNoop(publicInstance, 'forceUpdate');
-    }
-  }
-
-  /**
-   * Replaces all of the state. Always use this or `setState` to mutate state.
-   * You should treat `this.state` as immutable.
-   *
-   * There is no guarantee that `this.state` will be immediately updated, so
-   * accessing `this.state` after calling this method may return the old value.
-   *
-   * @param {ReactClass} publicInstance The instance that should rerender.
-   * @param {object|function} completeState Next state.
-   * @param {?function} callback Called after component is updated.
-   * @param {?string} Name of the calling function in the public API.
-   * @internal
-   */
-  enqueueReplaceState(
-    publicInstance: ReactComponent<any, any, any>,
-    completeState: Object | Function,
-    callback?: Function,
-    callerName?: string,
-  ) {
-    if (this.transaction.isInTransaction()) {
-      ReactUpdateQueue.enqueueReplaceState(
-        publicInstance,
-        completeState,
-        callback,
-        callerName,
-      );
-    } else {
-      warnNoop(publicInstance, 'replaceState');
-    }
-  }
-
-  /**
-   * Sets a subset of the state. This only exists because _pendingState is
-   * internal. This provides a merging strategy that is not available to deep
-   * properties which is confusing. TODO: Expose pendingState or don't use it
-   * during the merge.
-   *
-   * @param {ReactClass} publicInstance The instance that should rerender.
-   * @param {object|function} partialState Next partial state to be merged with state.
-   * @internal
-   */
-  enqueueSetState(
-    publicInstance: ReactComponent<any, any, any>,
-    partialState: Object | Function,
-    callback?: Function,
-    callerName?: string,
-  ) {
-    if (this.transaction.isInTransaction()) {
-      ReactUpdateQueue.enqueueSetState(
-        publicInstance,
-        partialState,
-        callback,
-        callerName,
-      );
-    } else {
-      warnNoop(publicInstance, 'setState');
-    }
-  }
-}
-
-module.exports = ReactServerUpdateQueue;
diff --git a/src/renderers/dom/test/ReactTestUtilsEntry.js b/src/renderers/dom/test/ReactTestUtilsEntry.js
index eaf1389e058..2fe8c2b9a57 100644
--- a/src/renderers/dom/test/ReactTestUtilsEntry.js
+++ b/src/renderers/dom/test/ReactTestUtilsEntry.js
@@ -11,20 +11,22 @@
 
 'use strict';
 
-var BrowserEventConstants = require('BrowserEventConstants');
-var React = require('react');
-var ReactDOM = require('react-dom');
-var ReactFiberTreeReflection = require('ReactFiberTreeReflection');
-var ReactInstanceMap = require('ReactInstanceMap');
-var ReactShallowRenderer = require('ReactShallowRendererEntry'); // TODO (bvaughn) Remove this import before 16.0.0
-var ReactTypeOfWork = require('ReactTypeOfWork');
-var SyntheticEvent = require('SyntheticEvent');
-
-var invariant = require('fbjs/lib/invariant');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import {topLevelTypes} from 'BrowserEventConstants';
+import React from 'react';
+import ReactDOM from 'react-dom';
+import {findCurrentFiberUsingSlowPath} from 'ReactFiberTreeReflection';
+import ReactInstanceMap from 'ReactInstanceMap';
+// TODO (bvaughn) Remove this import before 16.0.0:
+import ReactShallowRenderer from 'ReactShallowRendererEntry';
+import {
+  ClassComponent,
+  FunctionalComponent,
+  HostComponent,
+  HostText,
+} from 'ReactTypeOfWork';
+import SyntheticEvent from 'SyntheticEvent';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
 
 var {findDOMNode} = ReactDOM;
 var {
@@ -36,14 +38,6 @@ var {
   ReactDOMEventListener,
 } = ReactDOM.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED;
 
-var topLevelTypes = BrowserEventConstants.topLevelTypes;
-var {
-  ClassComponent,
-  FunctionalComponent,
-  HostComponent,
-  HostText,
-} = ReactTypeOfWork;
-
 // TODO (bvaughn) Remove this warning before 16.0.0
 // It's only being added for temporary deprecation notice in RN.
 let warnedAboutShallowRenderer = false;
@@ -64,42 +58,11 @@ function Event(suffix) {}
  * @class ReactTestUtils
  */
 
-function findAllInRenderedStackTreeInternal(inst, test) {
-  if (!inst || !inst.getPublicInstance) {
-    return [];
-  }
-  var publicInst = inst.getPublicInstance();
-  var ret = test(publicInst) ? [publicInst] : [];
-  var currentElement = inst._currentElement;
-  if (ReactTestUtils.isDOMComponent(publicInst)) {
-    var renderedChildren = inst._renderedChildren;
-    var key;
-    for (key in renderedChildren) {
-      if (!renderedChildren.hasOwnProperty(key)) {
-        continue;
-      }
-      ret = ret.concat(
-        findAllInRenderedStackTreeInternal(renderedChildren[key], test),
-      );
-    }
-  } else if (
-    React.isValidElement(currentElement) &&
-    typeof currentElement.type === 'function'
-  ) {
-    ret = ret.concat(
-      findAllInRenderedStackTreeInternal(inst._renderedComponent, test),
-    );
-  }
-  return ret;
-}
-
 function findAllInRenderedFiberTreeInternal(fiber, test) {
   if (!fiber) {
     return [];
   }
-  var currentParent = ReactFiberTreeReflection.findCurrentFiberUsingSlowPath(
-    fiber,
-  );
+  var currentParent = findCurrentFiberUsingSlowPath(fiber);
   if (!currentParent) {
     return [];
   }
@@ -190,45 +153,10 @@ var ReactTestUtils = {
       return false;
     }
     var internalInstance = ReactInstanceMap.get(inst);
-    var constructor = typeof internalInstance.tag === 'number'
-      ? internalInstance.type // Fiber reconciler
-      : internalInstance._currentElement.type; // Stack reconciler
-
+    var constructor = internalInstance.type;
     return constructor === type;
   },
 
-  // TODO: deprecate? It's undocumented and unused.
-  isCompositeComponentElement: function(inst) {
-    if (!React.isValidElement(inst)) {
-      return false;
-    }
-    // We check the prototype of the type that will get mounted, not the
-    // instance itself. This is a future proof way of duck typing.
-    var prototype = inst.type.prototype;
-    return (
-      typeof prototype.render === 'function' &&
-      typeof prototype.setState === 'function'
-    );
-  },
-
-  // TODO: deprecate? It's undocumented and unused.
-  isCompositeComponentElementWithType: function(inst, type) {
-    var internalInstance = ReactInstanceMap.get(inst);
-    var constructor = internalInstance._currentElement.type;
-
-    return !!(ReactTestUtils.isCompositeComponentElement(inst) &&
-      constructor === type);
-  },
-
-  // TODO: deprecate? It's undocumented and unused.
-  getRenderedChildOfCompositeComponent: function(inst) {
-    if (!ReactTestUtils.isCompositeComponent(inst)) {
-      return null;
-    }
-    var internalInstance = ReactInstanceMap.get(inst);
-    return internalInstance._renderedComponent.getPublicInstance();
-  },
-
   findAllInRenderedTree: function(inst, test) {
     if (!inst) {
       return [];
@@ -238,11 +166,7 @@ var ReactTestUtils = {
       'findAllInRenderedTree(...): instance must be a composite component',
     );
     var internalInstance = ReactInstanceMap.get(inst);
-    if (internalInstance && typeof internalInstance.tag === 'number') {
-      return findAllInRenderedFiberTreeInternal(internalInstance, test);
-    } else {
-      return findAllInRenderedStackTreeInternal(internalInstance, test);
-    }
+    return findAllInRenderedFiberTreeInternal(internalInstance, test);
   },
 
   /**
@@ -509,13 +433,15 @@ function buildSimulators() {
 }
 
 // Rebuild ReactTestUtils.Simulate whenever event plugins are injected
-var oldInjectEventPluginOrder = EventPluginHub.injection.injectEventPluginOrder;
-EventPluginHub.injection.injectEventPluginOrder = function() {
+var oldInjectEventPluginOrder =
+  EventPluginRegistry.injection.injectEventPluginOrder;
+EventPluginRegistry.injection.injectEventPluginOrder = function() {
   oldInjectEventPluginOrder.apply(this, arguments);
   buildSimulators();
 };
-var oldInjectEventPlugins = EventPluginHub.injection.injectEventPluginsByName;
-EventPluginHub.injection.injectEventPluginsByName = function() {
+var oldInjectEventPlugins =
+  EventPluginRegistry.injection.injectEventPluginsByName;
+EventPluginRegistry.injection.injectEventPluginsByName = function() {
   oldInjectEventPlugins.apply(this, arguments);
   buildSimulators();
 };
@@ -573,4 +499,6 @@ Object.keys(topLevelTypes).forEach(function(eventType) {
   );
 });
 
-module.exports = ReactTestUtils;
+// TODO: this fixes Rollup build but probably breaks Jest.
+// Need to figure something out.
+export default ReactTestUtils;
diff --git a/src/renderers/dom/test/__tests__/ReactTestUtils-test.js b/src/renderers/dom/test/__tests__/ReactTestUtils-test.js
index 76b54283f46..b873820ba0b 100644
--- a/src/renderers/dom/test/__tests__/ReactTestUtils-test.js
+++ b/src/renderers/dom/test/__tests__/ReactTestUtils-test.js
@@ -14,7 +14,6 @@
 let createRenderer;
 let React;
 let ReactDOM;
-let ReactDOMFeatureFlags;
 let ReactDOMServer;
 let ReactTestUtils;
 
@@ -25,7 +24,6 @@ describe('ReactTestUtils', () => {
     ReactDOM = require('react-dom');
     ReactDOMServer = require('react-dom/server');
     ReactTestUtils = require('react-dom/test-utils');
-    ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
   });
 
   it('can scryRenderedDOMComponentsWithClass with TextComponent', () => {
@@ -175,9 +173,7 @@ describe('ReactTestUtils', () => {
 
     const markup = ReactDOMServer.renderToString(<Root />);
     const testDocument = getTestDocument(markup);
-    const component = ReactDOMFeatureFlags.useFiber
-      ? ReactDOM.hydrate(<Root />, testDocument)
-      : ReactDOM.render(<Root />, testDocument);
+    const component = ReactDOM.hydrate(<Root />, testDocument);
 
     expect(component.refs.html.tagName).toBe('HTML');
     expect(component.refs.head.tagName).toBe('HEAD');
diff --git a/src/renderers/native/NativeMethodsMixin.js b/src/renderers/native/NativeMethodsMixin.js
index 977111b08a4..d1a2a6c0544 100644
--- a/src/renderers/native/NativeMethodsMixin.js
+++ b/src/renderers/native/NativeMethodsMixin.js
@@ -11,19 +11,19 @@
  */
 'use strict';
 
-const ReactNativeAttributePayload = require('ReactNativeAttributePayload');
-const TextInputState = require('TextInputState');
-const UIManager = require('UIManager');
+import ReactNativeAttributePayload from 'ReactNativeAttributePayload';
+import TextInputState from 'TextInputState';
+import UIManager from 'UIManager';
 
-const invariant = require('fbjs/lib/invariant');
-const findNodeHandle = require('findNodeHandle');
-const findNumericNodeHandle = require('findNumericNodeHandle');
+import invariant from 'fbjs/lib/invariant';
+import findNodeHandle from 'findNodeHandle';
+import findNumericNodeHandle from 'findNumericNodeHandle';
 
-const {
+import {
   mountSafeCallback,
   throwOnStylesProp,
   warnForStyleProps,
-} = require('NativeMethodsMixinUtils');
+} from 'NativeMethodsMixinUtils';
 
 import type {
   MeasureInWindowOnSuccessCallback,
@@ -204,4 +204,4 @@ if (__DEV__) {
   };
 }
 
-module.exports = NativeMethodsMixin;
+export default NativeMethodsMixin;
diff --git a/src/renderers/native/NativeMethodsMixinUtils.js b/src/renderers/native/NativeMethodsMixinUtils.js
index dad8a56dfcb..9f2d04f31eb 100644
--- a/src/renderers/native/NativeMethodsMixinUtils.js
+++ b/src/renderers/native/NativeMethodsMixinUtils.js
@@ -15,7 +15,7 @@
  * In the future, we should cleanup callbacks by cancelling them instead of
  * using this.
  */
-function mountSafeCallback(context: any, callback: ?Function): any {
+export function mountSafeCallback(context: any, callback: ?Function): any {
   return function() {
     if (!callback) {
       return undefined;
@@ -39,7 +39,7 @@ function mountSafeCallback(context: any, callback: ?Function): any {
   };
 }
 
-function throwOnStylesProp(component: any, props: any) {
+export function throwOnStylesProp(component: any, props: any) {
   if (props.styles !== undefined) {
     var owner = component._owner || null;
     var name = component.constructor.displayName;
@@ -59,7 +59,7 @@ function throwOnStylesProp(component: any, props: any) {
   }
 }
 
-function warnForStyleProps(props: any, validAttributes: any) {
+export function warnForStyleProps(props: any, validAttributes: any) {
   for (var key in validAttributes.style) {
     if (!(validAttributes[key] || props[key] === undefined)) {
       console.error(
@@ -74,9 +74,3 @@ function warnForStyleProps(props: any, validAttributes: any) {
     }
   }
 }
-
-module.exports = {
-  mountSafeCallback,
-  throwOnStylesProp,
-  warnForStyleProps,
-};
diff --git a/src/renderers/shared/stack/PooledClass.js b/src/renderers/native/PooledClass.js
similarity index 100%
rename from src/renderers/shared/stack/PooledClass.js
rename to src/renderers/native/PooledClass.js
diff --git a/src/renderers/native/ReactNativeAttributePayload.js b/src/renderers/native/ReactNativeAttributePayload.js
index 07dd2058de7..2a1e1c29904 100644
--- a/src/renderers/native/ReactNativeAttributePayload.js
+++ b/src/renderers/native/ReactNativeAttributePayload.js
@@ -11,10 +11,10 @@
  */
 'use strict';
 
-var ReactNativePropRegistry = require('ReactNativePropRegistry');
+import ReactNativePropRegistry from 'ReactNativePropRegistry';
 
-var deepDiffer = require('deepDiffer');
-var flattenStyle = require('flattenStyle');
+import deepDiffer from 'deepDiffer';
+import flattenStyle from 'flattenStyle';
 
 var emptyObject = {};
 
diff --git a/src/renderers/native/ReactNativeBridgeEventPlugin.js b/src/renderers/native/ReactNativeBridgeEventPlugin.js
index 121f7663a36..62b60914ae2 100644
--- a/src/renderers/native/ReactNativeBridgeEventPlugin.js
+++ b/src/renderers/native/ReactNativeBridgeEventPlugin.js
@@ -11,9 +11,12 @@
  */
 'use strict';
 
-var EventPropagators = require('EventPropagators');
-var SyntheticEvent = require('SyntheticEvent');
-var UIManager = require('UIManager');
+import {
+  accumulateTwoPhaseDispatches,
+  accumulateDirectDispatches,
+} from 'EventPropagators';
+import SyntheticEvent from 'SyntheticEvent';
+import UIManager from 'UIManager';
 
 var customBubblingEventTypes = UIManager.customBubblingEventTypes;
 var customDirectEventTypes = UIManager.customDirectEventTypes;
@@ -51,9 +54,9 @@ var ReactNativeBridgeEventPlugin = {
       nativeEventTarget,
     );
     if (bubbleDispatchConfig) {
-      EventPropagators.accumulateTwoPhaseDispatches(event);
+      accumulateTwoPhaseDispatches(event);
     } else if (directDispatchConfig) {
-      EventPropagators.accumulateDirectDispatches(event);
+      accumulateDirectDispatches(event);
     } else {
       return null;
     }
@@ -61,4 +64,4 @@ var ReactNativeBridgeEventPlugin = {
   },
 };
 
-module.exports = ReactNativeBridgeEventPlugin;
+export default ReactNativeBridgeEventPlugin;
diff --git a/src/renderers/native/ReactNativeComponent.js b/src/renderers/native/ReactNativeComponent.js
index 91210af31a9..fb81096e4a4 100644
--- a/src/renderers/native/ReactNativeComponent.js
+++ b/src/renderers/native/ReactNativeComponent.js
@@ -13,15 +13,15 @@
 
 'use strict';
 
-const React = require('react');
-const ReactNativeAttributePayload = require('ReactNativeAttributePayload');
-const TextInputState = require('TextInputState');
-const UIManager = require('UIManager');
+import React from 'react';
+import ReactNativeAttributePayload from 'ReactNativeAttributePayload';
+import TextInputState from 'TextInputState';
+import UIManager from 'UIManager';
 
-const findNodeHandle = require('findNodeHandle');
-const findNumericNodeHandle = require('findNumericNodeHandle');
+import findNodeHandle from 'findNodeHandle';
+import findNumericNodeHandle from 'findNumericNodeHandle';
 
-const {mountSafeCallback} = require('NativeMethodsMixinUtils');
+import {mountSafeCallback} from 'NativeMethodsMixinUtils';
 
 import type {
   MeasureInWindowOnSuccessCallback,
@@ -177,4 +177,4 @@ class ReactNativeComponent<DefaultProps, Props, State>
 // eslint-disable-next-line no-unused-expressions
 (ReactNativeComponent.prototype: NativeMethodsMixinType);
 
-module.exports = ReactNativeComponent;
+export default ReactNativeComponent;
diff --git a/src/renderers/native/ReactNativeComponentTree.js b/src/renderers/native/ReactNativeComponentTree.js
index eb856b70ab2..45574e31a3e 100644
--- a/src/renderers/native/ReactNativeComponentTree.js
+++ b/src/renderers/native/ReactNativeComponentTree.js
@@ -11,79 +11,36 @@
 
 'use strict';
 
-var invariant = require('fbjs/lib/invariant');
+import invariant from 'fbjs/lib/invariant';
 
 var instanceCache = {};
 var instanceProps = {};
 
-/**
- * Drill down (through composites and empty components) until we get a host or
- * host text component.
- *
- * This is pretty polymorphic but unavoidable with the current structure we have
- * for `_renderedChildren`.
- */
-function getRenderedHostOrTextFromComponent(component) {
-  var rendered;
-  while ((rendered = component._renderedComponent)) {
-    component = rendered;
-  }
-  return component;
-}
-
-/**
- * Populate `_hostNode` on the rendered host/text component with the given
- * DOM node. The passed `inst` can be a composite.
- */
-function precacheNode(inst, tag) {
-  var nativeInst = getRenderedHostOrTextFromComponent(inst);
-  instanceCache[tag] = nativeInst;
-}
-
-function precacheFiberNode(hostInst, tag) {
+export function precacheFiberNode(hostInst, tag) {
   instanceCache[tag] = hostInst;
 }
 
-function uncacheNode(inst) {
-  var tag = inst._rootNodeID;
-  if (tag) {
-    delete instanceCache[tag];
-  }
-}
-
-function uncacheFiberNode(tag) {
+export function uncacheFiberNode(tag) {
   delete instanceCache[tag];
   delete instanceProps[tag];
 }
 
-function getInstanceFromTag(tag) {
+export function getInstanceFromNode(tag) {
   return instanceCache[tag] || null;
 }
 
-function getTagFromInstance(inst) {
+export const getClosestInstanceFromNode = getInstanceFromNode;
+
+export function getNodeFromInstance(inst) {
   var tag = inst.stateNode._nativeTag;
   invariant(tag, 'All native instances should have a tag.');
   return tag;
 }
 
-function getFiberCurrentPropsFromNode(stateNode) {
+export function getFiberCurrentPropsFromNode(stateNode) {
   return instanceProps[stateNode._nativeTag] || null;
 }
 
-function updateFiberProps(tag, props) {
+export function updateFiberProps(tag, props) {
   instanceProps[tag] = props;
 }
-
-var ReactNativeComponentTree = {
-  getClosestInstanceFromNode: getInstanceFromTag,
-  getInstanceFromNode: getInstanceFromTag,
-  getNodeFromInstance: getTagFromInstance,
-  precacheFiberNode,
-  precacheNode,
-  uncacheFiberNode,
-  uncacheNode,
-  getFiberCurrentPropsFromNode,
-  updateFiberProps,
-};
-
-module.exports = ReactNativeComponentTree;
diff --git a/src/renderers/native/ReactNativeEventEmitter.js b/src/renderers/native/ReactNativeEventEmitter.js
index 19d31b24b0a..4e5fae6d1d0 100644
--- a/src/renderers/native/ReactNativeEventEmitter.js
+++ b/src/renderers/native/ReactNativeEventEmitter.js
@@ -11,16 +11,13 @@
  */
 'use strict';
 
-var EventPluginHub = require('EventPluginHub');
-var EventPluginRegistry = require('EventPluginRegistry');
-var ReactEventEmitterMixin = require('ReactEventEmitterMixin');
-var ReactNativeComponentTree = require('ReactNativeComponentTree');
-var ReactNativeTagHandles = require('ReactNativeTagHandles');
-var ReactGenericBatching = require('ReactGenericBatching');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import {getListener} from 'EventPluginHub';
+import {handleTopLevel} from 'ReactEventEmitterMixin';
+import {registrationNames} from 'EventPluginRegistry';
+import {getInstanceFromNode} from 'ReactNativeComponentTree';
+import {tagsStartAt} from 'ReactNativeTagHandles';
+import {batchedUpdates} from 'ReactGenericBatching';
+import warning from 'fbjs/lib/warning';
 
 /**
  * Version of `ReactBrowserEventEmitter` that works on the receiving side of a
@@ -80,124 +77,108 @@ var removeTouchesAtIndices = function(
   return rippedOut;
 };
 
-var ReactNativeEventEmitter = {
-  ...ReactEventEmitterMixin,
-
-  registrationNames: EventPluginRegistry.registrationNameModules,
-
-  getListener: EventPluginHub.getListener,
+export {handleTopLevel, registrationNames, getListener};
 
-  /**
-   * Internal version of `receiveEvent` in terms of normalized (non-tag)
-   * `rootNodeID`.
-   *
-   * @see receiveEvent.
-   *
-   * @param {rootNodeID} rootNodeID React root node ID that event occurred on.
-   * @param {TopLevelType} topLevelType Top level type of event.
-   * @param {object} nativeEventParam Object passed from native.
-   */
-  _receiveRootNodeIDEvent: function(
-    rootNodeID: number,
-    topLevelType: string,
-    nativeEventParam: Object,
-  ) {
-    var nativeEvent = nativeEventParam || EMPTY_NATIVE_EVENT;
-    var inst = ReactNativeComponentTree.getInstanceFromNode(rootNodeID);
-    ReactGenericBatching.batchedUpdates(function() {
-      ReactNativeEventEmitter.handleTopLevel(
-        topLevelType,
-        inst,
-        nativeEvent,
-        nativeEvent.target,
-      );
-    });
-    // React Native doesn't use ReactControlledComponent but if it did, here's
-    // where it would do it.
-  },
+/**
+ * Internal version of `receiveEvent` in terms of normalized (non-tag)
+ * `rootNodeID`.
+ *
+ * @see receiveEvent.
+ *
+ * @param {rootNodeID} rootNodeID React root node ID that event occurred on.
+ * @param {TopLevelType} topLevelType Top level type of event.
+ * @param {object} nativeEventParam Object passed from native.
+ */
+export function _receiveRootNodeIDEvent(
+  rootNodeID: number,
+  topLevelType: string,
+  nativeEventParam: Object,
+) {
+  var nativeEvent = nativeEventParam || EMPTY_NATIVE_EVENT;
+  var inst = getInstanceFromNode(rootNodeID);
+  batchedUpdates(function() {
+    handleTopLevel(topLevelType, inst, nativeEvent, nativeEvent.target);
+  });
+  // React Native doesn't use ReactControlledComponent but if it did, here's
+  // where it would do it.
+}
 
-  /**
-   * Publicly exposed method on module for native objc to invoke when a top
-   * level event is extracted.
-   * @param {rootNodeID} rootNodeID React root node ID that event occurred on.
-   * @param {TopLevelType} topLevelType Top level type of event.
-   * @param {object} nativeEventParam Object passed from native.
-   */
-  receiveEvent: function(
-    tag: number,
-    topLevelType: string,
-    nativeEventParam: Object,
-  ) {
-    var rootNodeID = tag;
-    ReactNativeEventEmitter._receiveRootNodeIDEvent(
-      rootNodeID,
-      topLevelType,
-      nativeEventParam,
-    );
-  },
+/**
+ * Publicly exposed method on module for native objc to invoke when a top
+ * level event is extracted.
+ * @param {rootNodeID} rootNodeID React root node ID that event occurred on.
+ * @param {TopLevelType} topLevelType Top level type of event.
+ * @param {object} nativeEventParam Object passed from native.
+ */
+export function receiveEvent(
+  tag: number,
+  topLevelType: string,
+  nativeEventParam: Object,
+) {
+  var rootNodeID = tag;
+  _receiveRootNodeIDEvent(rootNodeID, topLevelType, nativeEventParam);
+}
 
-  /**
-   * Simple multi-wrapper around `receiveEvent` that is intended to receive an
-   * efficient representation of `Touch` objects, and other information that
-   * can be used to construct W3C compliant `Event` and `Touch` lists.
-   *
-   * This may create dispatch behavior that differs than web touch handling. We
-   * loop through each of the changed touches and receive it as a single event.
-   * So two `touchStart`/`touchMove`s that occur simultaneously are received as
-   * two separate touch event dispatches - when they arguably should be one.
-   *
-   * This implementation reuses the `Touch` objects themselves as the `Event`s
-   * since we dispatch an event for each touch (though that might not be spec
-   * compliant). The main purpose of reusing them is to save allocations.
-   *
-   * TODO: Dispatch multiple changed touches in one event. The bubble path
-   * could be the first common ancestor of all the `changedTouches`.
-   *
-   * One difference between this behavior and W3C spec: cancelled touches will
-   * not appear in `.touches`, or in any future `.touches`, though they may
-   * still be "actively touching the surface".
-   *
-   * Web desktop polyfills only need to construct a fake touch event with
-   * identifier 0, also abandoning traditional click handlers.
-   */
-  receiveTouches: function(
-    eventTopLevelType: string,
-    touches: Array<Object>,
-    changedIndices: Array<number>,
-  ) {
-    var changedTouches = eventTopLevelType === 'topTouchEnd' ||
-      eventTopLevelType === 'topTouchCancel'
-      ? removeTouchesAtIndices(touches, changedIndices)
-      : touchSubsequence(touches, changedIndices);
+/**
+ * Simple multi-wrapper around `receiveEvent` that is intended to receive an
+ * efficient representation of `Touch` objects, and other information that
+ * can be used to construct W3C compliant `Event` and `Touch` lists.
+ *
+ * This may create dispatch behavior that differs than web touch handling. We
+ * loop through each of the changed touches and receive it as a single event.
+ * So two `touchStart`/`touchMove`s that occur simultaneously are received as
+ * two separate touch event dispatches - when they arguably should be one.
+ *
+ * This implementation reuses the `Touch` objects themselves as the `Event`s
+ * since we dispatch an event for each touch (though that might not be spec
+ * compliant). The main purpose of reusing them is to save allocations.
+ *
+ * TODO: Dispatch multiple changed touches in one event. The bubble path
+ * could be the first common ancestor of all the `changedTouches`.
+ *
+ * One difference between this behavior and W3C spec: cancelled touches will
+ * not appear in `.touches`, or in any future `.touches`, though they may
+ * still be "actively touching the surface".
+ *
+ * Web desktop polyfills only need to construct a fake touch event with
+ * identifier 0, also abandoning traditional click handlers.
+ */
+export function receiveTouches(
+  eventTopLevelType: string,
+  touches: Array<Object>,
+  changedIndices: Array<number>,
+) {
+  var changedTouches = eventTopLevelType === 'topTouchEnd' ||
+    eventTopLevelType === 'topTouchCancel'
+    ? removeTouchesAtIndices(touches, changedIndices)
+    : touchSubsequence(touches, changedIndices);
 
-    for (var jj = 0; jj < changedTouches.length; jj++) {
-      var touch = changedTouches[jj];
-      // Touch objects can fulfill the role of `DOM` `Event` objects if we set
-      // the `changedTouches`/`touches`. This saves allocations.
-      touch.changedTouches = changedTouches;
-      touch.touches = touches;
-      var nativeEvent = touch;
-      var rootNodeID = null;
-      var target = nativeEvent.target;
-      if (target !== null && target !== undefined) {
-        if (target < ReactNativeTagHandles.tagsStartAt) {
-          if (__DEV__) {
-            warning(
-              false,
-              'A view is reporting that a touch occurred on tag zero.',
-            );
-          }
-        } else {
-          rootNodeID = target;
+  for (var jj = 0; jj < changedTouches.length; jj++) {
+    var touch = changedTouches[jj];
+    // Touch objects can fulfill the role of `DOM` `Event` objects if we set
+    // the `changedTouches`/`touches`. This saves allocations.
+    touch.changedTouches = changedTouches;
+    touch.touches = touches;
+    var nativeEvent = touch;
+    var rootNodeID = null;
+    var target = nativeEvent.target;
+    if (target !== null && target !== undefined) {
+      if (target < tagsStartAt) {
+        if (__DEV__) {
+          warning(
+            false,
+            'A view is reporting that a touch occurred on tag zero.',
+          );
         }
+      } else {
+        rootNodeID = target;
       }
-      ReactNativeEventEmitter._receiveRootNodeIDEvent(
-        rootNodeID,
-        eventTopLevelType,
-        nativeEvent,
-      );
     }
-  },
-};
-
-module.exports = ReactNativeEventEmitter;
+    _receiveRootNodeIDEvent(
+      // TODO: Flow uncovered an error here
+      rootNodeID,
+      eventTopLevelType,
+      nativeEvent,
+    );
+  }
+}
diff --git a/src/renderers/native/ReactNativeEventPluginOrder.js b/src/renderers/native/ReactNativeEventPluginOrder.js
index b1b5f66d110..6f172b8ef72 100644
--- a/src/renderers/native/ReactNativeEventPluginOrder.js
+++ b/src/renderers/native/ReactNativeEventPluginOrder.js
@@ -16,4 +16,4 @@ var ReactNativeEventPluginOrder = [
   'ReactNativeBridgeEventPlugin',
 ];
 
-module.exports = ReactNativeEventPluginOrder;
+export default ReactNativeEventPluginOrder;
diff --git a/src/renderers/native/ReactNativeFiberEntry.js b/src/renderers/native/ReactNativeFiberEntry.js
index 3dd78acf40a..f4b12452cae 100644
--- a/src/renderers/native/ReactNativeFiberEntry.js
+++ b/src/renderers/native/ReactNativeFiberEntry.js
@@ -12,39 +12,49 @@
 
 'use strict';
 
-const ReactFiberErrorLogger = require('ReactFiberErrorLogger');
-const ReactGenericBatching = require('ReactGenericBatching');
-const ReactNativeFiberErrorDialog = require('ReactNativeFiberErrorDialog');
-const ReactPortal = require('ReactPortal');
-const ReactNativeComponentTree = require('ReactNativeComponentTree');
-const ReactNativeFiberRenderer = require('ReactNativeFiberRenderer');
-const ReactNativeFiberInspector = require('ReactNativeFiberInspector');
-const ReactVersion = require('ReactVersion');
-const UIManager = require('UIManager');
-
-const findNumericNodeHandle = require('findNumericNodeHandle');
-
-const {injectInternals} = require('ReactFiberDevToolsHook');
+import 'ReactNativeInjection';
+import {
+  injection as ReactFiberErrorLoggerInjection,
+} from 'ReactFiberErrorLogger';
+import {
+  injection as ReactGenericBatchingInjection,
+  batchedUpdates,
+} from 'ReactGenericBatching';
+import ReactNativeComponent from 'ReactNativeComponent';
+import {showFiberErrorDialog} from 'ReactNativeFiberErrorDialog';
+import {createPortal} from 'ReactPortal';
+import {getClosestInstanceFromNode} from 'ReactNativeComponentTree';
+import ReactNativeFiberRenderer from 'ReactNativeFiberRenderer';
+import {getInspectorDataForViewTag} from 'ReactNativeFiberInspector';
+import ReactVersion from 'ReactVersion';
+import UIManager from 'UIManager';
+import findNumericNodeHandle from 'findNumericNodeHandle';
+import {injectInternals} from 'ReactFiberDevToolsHook';
+
+// These can be removed once we stop exposing them to RN internals.
+import NativeMethodsMixin from 'NativeMethodsMixin';
+import ReactGlobalSharedState from 'ReactGlobalSharedState';
+import * as ReactNativeComponentTree from 'ReactNativeComponentTree';
+import ReactNativePropRegistry from 'ReactNativePropRegistry';
+import TouchHistoryMath from 'TouchHistoryMath';
+import createReactNativeComponentClass from 'createReactNativeComponentClass';
+import takeSnapshot from 'takeSnapshot';
 
 import type {ReactNativeType} from 'ReactNativeTypes';
 import type {ReactNodeList} from 'ReactTypes';
 
-require('ReactNativeInjection');
-
-ReactGenericBatching.injection.injectFiberBatchedUpdates(
+ReactGenericBatchingInjection.injectBatchedUpdatesImplementation(
   ReactNativeFiberRenderer.batchedUpdates,
 );
 
-const roots = new Map();
-
 // Intercept lifecycle errors and ensure they are shown with the correct stack
 // trace within the native redbox component.
-ReactFiberErrorLogger.injection.injectDialog(
-  ReactNativeFiberErrorDialog.showDialog,
-);
+ReactFiberErrorLoggerInjection.injectDialog(showFiberErrorDialog);
+
+const roots = new Map();
 
 const ReactNativeFiber: ReactNativeType = {
-  NativeComponent: require('ReactNativeComponent'),
+  NativeComponent: ReactNativeComponent,
 
   findNodeHandle: findNumericNodeHandle,
 
@@ -84,24 +94,24 @@ const ReactNativeFiber: ReactNativeType = {
     containerTag: number,
     key: ?string = null,
   ) {
-    return ReactPortal.createPortal(children, containerTag, null, key);
+    return createPortal(children, containerTag, null, key);
   },
 
-  unstable_batchedUpdates: ReactGenericBatching.batchedUpdates,
+  unstable_batchedUpdates: batchedUpdates,
 
   flushSync: ReactNativeFiberRenderer.flushSync,
 
   __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: {
     // Used as a mixin in many createClass-based components
-    NativeMethodsMixin: require('NativeMethodsMixin'),
+    NativeMethodsMixin,
 
     // Used by react-native-github/Libraries/ components
-    ReactGlobalSharedState: require('ReactGlobalSharedState'), // Systrace
-    ReactNativeComponentTree: require('ReactNativeComponentTree'), // InspectorUtils, ScrollResponder
-    ReactNativePropRegistry: require('ReactNativePropRegistry'), // flattenStyle, Stylesheet
-    TouchHistoryMath: require('TouchHistoryMath'), // PanResponder
-    createReactNativeComponentClass: require('createReactNativeComponentClass'), // eg Text
-    takeSnapshot: require('takeSnapshot'), // react-native-implementation
+    ReactGlobalSharedState, // Systrace
+    ReactNativeComponentTree, // InspectorUtils, ScrollResponder
+    ReactNativePropRegistry, // flattenStyle, Stylesheet
+    TouchHistoryMath, // PanResponder
+    createReactNativeComponentClass, // eg Text
+    takeSnapshot, // react-native-implementation
   },
 };
 
@@ -110,20 +120,33 @@ if (__DEV__) {
   Object.assign(
     ReactNativeFiber.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED,
     {
-      ReactDebugTool: require('ReactDebugTool'), // RCTRenderingPerf, Systrace
-      ReactPerf: require('ReactPerf'), // ReactPerfStallHandler, RCTRenderingPerf
+      // TODO: none of these work since Fiber. Remove these dependencies.
+      // Used by RCTRenderingPerf, Systrace:
+      ReactDebugTool: {
+        addHook() {},
+        removeHook() {},
+      },
+      // Used by ReactPerfStallHandler, RCTRenderingPerf:
+      ReactPerf: {
+        start() {},
+        stop() {},
+        printInclusive() {},
+        printWasted() {},
+      },
     },
   );
 }
 
 injectInternals({
-  findFiberByHostInstance: ReactNativeComponentTree.getClosestInstanceFromNode,
+  findFiberByHostInstance: getClosestInstanceFromNode,
   findHostInstanceByFiber: ReactNativeFiberRenderer.findHostInstance,
-  getInspectorDataForViewTag: ReactNativeFiberInspector.getInspectorDataForViewTag,
+  getInspectorDataForViewTag,
   // This is an enum because we may add more (e.g. profiler build)
   bundleType: __DEV__ ? 1 : 0,
   version: ReactVersion,
   rendererPackageName: 'react-native',
 });
 
-module.exports = ReactNativeFiber;
+// TODO: this fixes Rollup build but probably breaks Jest.
+// Need to figure something out.
+export default ReactNativeFiber;
diff --git a/src/renderers/native/ReactNativeFiberErrorDialog.js b/src/renderers/native/ReactNativeFiberErrorDialog.js
index 69835c1cf43..ecc4cb6921a 100644
--- a/src/renderers/native/ReactNativeFiberErrorDialog.js
+++ b/src/renderers/native/ReactNativeFiberErrorDialog.js
@@ -20,7 +20,7 @@ import type {CapturedError} from 'ReactFiberScheduler';
  * Intercept lifecycle errors and ensure they are shown with the correct stack
  * trace within the native redbox component.
  */
-function ReactNativeFiberErrorDialog(capturedError: CapturedError): boolean {
+export function showFiberErrorDialog(capturedError: CapturedError): boolean {
   const {componentStack, error} = capturedError;
 
   let errorToHandle: Error;
@@ -52,5 +52,3 @@ function ReactNativeFiberErrorDialog(capturedError: CapturedError): boolean {
   // done above by calling ExceptionsManager.
   return false;
 }
-
-module.exports.showDialog = ReactNativeFiberErrorDialog;
diff --git a/src/renderers/native/ReactNativeFiberHostComponent.js b/src/renderers/native/ReactNativeFiberHostComponent.js
index 67e9af67d70..8b97fde7719 100644
--- a/src/renderers/native/ReactNativeFiberHostComponent.js
+++ b/src/renderers/native/ReactNativeFiberHostComponent.js
@@ -13,11 +13,12 @@
 
 'use strict';
 
-var ReactNativeAttributePayload = require('ReactNativeAttributePayload');
-var TextInputState = require('TextInputState');
-var UIManager = require('UIManager');
-
-var {mountSafeCallback, warnForStyleProps} = require('NativeMethodsMixinUtils');
+import {
+  create as createReactNativeAttributePayload,
+} from 'ReactNativeAttributePayload';
+import {blurTextInput, focusTextInput} from 'TextInputState';
+import UIManager from 'UIManager';
+import {mountSafeCallback, warnForStyleProps} from 'NativeMethodsMixinUtils';
 
 import type {
   MeasureInWindowOnSuccessCallback,
@@ -49,11 +50,11 @@ class ReactNativeFiberHostComponent {
   }
 
   blur() {
-    TextInputState.blurTextInput(this._nativeTag);
+    blurTextInput(this._nativeTag);
   }
 
   focus() {
-    TextInputState.focusTextInput(this._nativeTag);
+    focusTextInput(this._nativeTag);
   }
 
   measure(callback: MeasureOnSuccessCallback) {
@@ -85,7 +86,7 @@ class ReactNativeFiberHostComponent {
       warnForStyleProps(nativeProps, this.viewConfig.validAttributes);
     }
 
-    var updatePayload = ReactNativeAttributePayload.create(
+    var updatePayload = createReactNativeAttributePayload(
       nativeProps,
       this.viewConfig.validAttributes,
     );
@@ -106,4 +107,4 @@ class ReactNativeFiberHostComponent {
 // eslint-disable-next-line no-unused-expressions
 (ReactNativeFiberHostComponent.prototype: NativeMethodsMixinType);
 
-module.exports = ReactNativeFiberHostComponent;
+export default ReactNativeFiberHostComponent;
diff --git a/src/renderers/native/ReactNativeFiberInspector.js b/src/renderers/native/ReactNativeFiberInspector.js
index bd9d73f00f3..a04dd3c4a36 100644
--- a/src/renderers/native/ReactNativeFiberInspector.js
+++ b/src/renderers/native/ReactNativeFiberInspector.js
@@ -11,21 +11,25 @@
  */
 'use strict';
 
-const ReactNativeComponentTree = require('ReactNativeComponentTree');
-const ReactFiberTreeReflection = require('ReactFiberTreeReflection');
-const getComponentName = require('getComponentName');
-const emptyObject = require('fbjs/lib/emptyObject');
-const ReactTypeOfWork = require('ReactTypeOfWork');
-const UIManager = require('UIManager');
-const invariant = require('fbjs/lib/invariant');
-
-const {getClosestInstanceFromNode} = ReactNativeComponentTree;
-const {findCurrentFiberUsingSlowPath} = ReactFiberTreeReflection;
-const {HostComponent} = ReactTypeOfWork;
+import {getClosestInstanceFromNode} from 'ReactNativeComponentTree';
+import {
+  findCurrentHostFiber,
+  findCurrentFiberUsingSlowPath,
+} from 'ReactFiberTreeReflection';
+import getComponentName from 'getComponentName';
+import emptyObject from 'fbjs/lib/emptyObject';
+import {HostComponent} from 'ReactTypeOfWork';
+import UIManager from 'UIManager';
+import invariant from 'fbjs/lib/invariant';
 
 import type {Fiber} from 'ReactFiber';
 
-let getInspectorDataForViewTag;
+export let getInspectorDataForViewTag = () => {
+  invariant(
+    false,
+    'getInspectorDataForViewTag() is not available in production',
+  );
+};
 
 if (__DEV__) {
   var traverseOwnerTreeUp = function(hierarchy, instance: any) {
@@ -53,7 +57,7 @@ if (__DEV__) {
   };
 
   var getHostProps = function(fiber) {
-    const host = ReactFiberTreeReflection.findCurrentHostFiber(fiber);
+    const host = findCurrentHostFiber(fiber);
     if (host) {
       return host.memoizedProps || emptyObject;
     }
@@ -116,15 +120,4 @@ if (__DEV__) {
       source,
     };
   };
-} else {
-  getInspectorDataForViewTag = () => {
-    invariant(
-      false,
-      'getInspectorDataForViewTag() is not available in production',
-    );
-  };
 }
-
-module.exports = {
-  getInspectorDataForViewTag,
-};
diff --git a/src/renderers/native/ReactNativeFiberRenderer.js b/src/renderers/native/ReactNativeFiberRenderer.js
index ee1dbccb4ca..4c166f18be3 100644
--- a/src/renderers/native/ReactNativeFiberRenderer.js
+++ b/src/renderers/native/ReactNativeFiberRenderer.js
@@ -12,17 +12,24 @@
 
 'use strict';
 
-const ReactFiberReconciler = require('ReactFiberReconciler');
-const ReactNativeAttributePayload = require('ReactNativeAttributePayload');
-const ReactNativeComponentTree = require('ReactNativeComponentTree');
-const ReactNativeFiberHostComponent = require('ReactNativeFiberHostComponent');
-const ReactNativeTagHandles = require('ReactNativeTagHandles');
-const ReactNativeViewConfigRegistry = require('ReactNativeViewConfigRegistry');
-const UIManager = require('UIManager');
-
-const deepFreezeAndThrowOnMutationInDev = require('deepFreezeAndThrowOnMutationInDev');
-const emptyObject = require('fbjs/lib/emptyObject');
-const invariant = require('fbjs/lib/invariant');
+import ReactFiberReconciler from 'ReactFiberReconciler';
+import {
+  create as createAttributePayload,
+  diff as diffAttributePayload,
+} from 'ReactNativeAttributePayload';
+import {
+  precacheFiberNode,
+  uncacheFiberNode,
+  updateFiberProps,
+} from 'ReactNativeComponentTree';
+import ReactNativeFiberHostComponent from 'ReactNativeFiberHostComponent';
+import {allocateTag} from 'ReactNativeTagHandles';
+import {get as getFromViewConfigRegistry} from 'ReactNativeViewConfigRegistry';
+import UIManager from 'UIManager';
+import deepFreezeAndThrowOnMutationInDev
+  from 'deepFreezeAndThrowOnMutationInDev';
+import emptyObject from 'fbjs/lib/emptyObject';
+import invariant from 'fbjs/lib/invariant';
 
 import type {
   ReactNativeBaseComponentViewConfig,
@@ -37,12 +44,6 @@ export type Instance = {
 export type Props = Object;
 export type TextInstance = number;
 
-const {
-  precacheFiberNode,
-  uncacheFiberNode,
-  updateFiberProps,
-} = ReactNativeComponentTree;
-
 function recursivelyUncacheFiberNode(node: Instance | TextInstance) {
   if (typeof node === 'number') {
     // Leaf node (eg text)
@@ -137,7 +138,7 @@ const NativeRenderer = ReactFiberReconciler({
 
     updateFiberProps(instance._nativeTag, newProps);
 
-    const updatePayload = ReactNativeAttributePayload.diff(
+    const updatePayload = diffAttributePayload(
       oldProps,
       newProps,
       viewConfig.validAttributes,
@@ -162,8 +163,8 @@ const NativeRenderer = ReactFiberReconciler({
     hostContext: {},
     internalInstanceHandle: Object,
   ): Instance {
-    const tag = ReactNativeTagHandles.allocateTag();
-    const viewConfig = ReactNativeViewConfigRegistry.get(type);
+    const tag = allocateTag();
+    const viewConfig = getFromViewConfigRegistry(type);
 
     if (__DEV__) {
       for (const key in viewConfig.validAttributes) {
@@ -173,7 +174,7 @@ const NativeRenderer = ReactFiberReconciler({
       }
     }
 
-    const updatePayload = ReactNativeAttributePayload.create(
+    const updatePayload = createAttributePayload(
       props,
       viewConfig.validAttributes,
     );
@@ -201,7 +202,7 @@ const NativeRenderer = ReactFiberReconciler({
     hostContext: {},
     internalInstanceHandle: Object,
   ): TextInstance {
-    const tag = ReactNativeTagHandles.allocateTag();
+    const tag = allocateTag();
 
     UIManager.createView(
       tag, // reactTag
@@ -383,4 +384,4 @@ const NativeRenderer = ReactFiberReconciler({
   useSyncScheduling: true,
 });
 
-module.exports = NativeRenderer;
+export default NativeRenderer;
diff --git a/src/renderers/native/ReactNativeGlobalResponderHandler.js b/src/renderers/native/ReactNativeGlobalResponderHandler.js
index d586bcc6c02..c0ef0f376ba 100644
--- a/src/renderers/native/ReactNativeGlobalResponderHandler.js
+++ b/src/renderers/native/ReactNativeGlobalResponderHandler.js
@@ -10,7 +10,7 @@
  */
 'use strict';
 
-var UIManager = require('UIManager');
+import UIManager from 'UIManager';
 
 var ReactNativeGlobalResponderHandler = {
   onChange: function(from, to, blockNativeResponder) {
@@ -23,4 +23,4 @@ var ReactNativeGlobalResponderHandler = {
   },
 };
 
-module.exports = ReactNativeGlobalResponderHandler;
+export default ReactNativeGlobalResponderHandler;
diff --git a/src/renderers/native/ReactNativeInjection.js b/src/renderers/native/ReactNativeInjection.js
index b94c4921cbc..3f34481eb04 100644
--- a/src/renderers/native/ReactNativeInjection.js
+++ b/src/renderers/native/ReactNativeInjection.js
@@ -17,17 +17,17 @@
  * ensures it exists in the dependency graph and can be `require`d.
  * TODO: require this in packager, not in React #10932517
  */
-require('InitializeCore');
-
-var EventPluginHub = require('EventPluginHub');
-var EventPluginUtils = require('EventPluginUtils');
-var RCTEventEmitter = require('RCTEventEmitter');
-var ReactNativeBridgeEventPlugin = require('ReactNativeBridgeEventPlugin');
-var ReactNativeComponentTree = require('ReactNativeComponentTree');
-var ReactNativeEventEmitter = require('ReactNativeEventEmitter');
-var ReactNativeEventPluginOrder = require('ReactNativeEventPluginOrder');
-var ReactNativeGlobalResponderHandler = require('ReactNativeGlobalResponderHandler');
-var ResponderEventPlugin = require('ResponderEventPlugin');
+import 'InitializeCore';
+import {injection as EventPluginRegistryInjection} from 'EventPluginRegistry';
+import {injection as EventPluginUtilsInjection} from 'EventPluginUtils';
+import RCTEventEmitter from 'RCTEventEmitter';
+import ReactNativeBridgeEventPlugin from 'ReactNativeBridgeEventPlugin';
+import * as ReactNativeComponentTree from 'ReactNativeComponentTree';
+import * as ReactNativeEventEmitter from 'ReactNativeEventEmitter';
+import ReactNativeEventPluginOrder from 'ReactNativeEventPluginOrder';
+import ReactNativeGlobalResponderHandler
+  from 'ReactNativeGlobalResponderHandler';
+import ResponderEventPlugin from 'ResponderEventPlugin';
 
 /**
  * Register the event emitter with the native bridge
@@ -37,8 +37,10 @@ RCTEventEmitter.register(ReactNativeEventEmitter);
 /**
  * Inject module for resolving DOM hierarchy and plugin ordering.
  */
-EventPluginHub.injection.injectEventPluginOrder(ReactNativeEventPluginOrder);
-EventPluginUtils.injection.injectComponentTree(ReactNativeComponentTree);
+EventPluginRegistryInjection.injectEventPluginOrder(
+  ReactNativeEventPluginOrder,
+);
+EventPluginUtilsInjection.injectComponentTree(ReactNativeComponentTree);
 
 ResponderEventPlugin.injection.injectGlobalResponderHandler(
   ReactNativeGlobalResponderHandler,
@@ -48,7 +50,7 @@ ResponderEventPlugin.injection.injectGlobalResponderHandler(
  * Some important event plugins included by default (without having to require
  * them).
  */
-EventPluginHub.injection.injectEventPluginsByName({
+EventPluginRegistryInjection.injectEventPluginsByName({
   ResponderEventPlugin: ResponderEventPlugin,
   ReactNativeBridgeEventPlugin: ReactNativeBridgeEventPlugin,
 });
diff --git a/src/renderers/native/ReactNativePropRegistry.js b/src/renderers/native/ReactNativePropRegistry.js
index 3cffb9acf3b..8004db3ea91 100644
--- a/src/renderers/native/ReactNativePropRegistry.js
+++ b/src/renderers/native/ReactNativePropRegistry.js
@@ -41,4 +41,4 @@ class ReactNativePropRegistry {
   }
 }
 
-module.exports = ReactNativePropRegistry;
+export default ReactNativePropRegistry;
diff --git a/src/renderers/native/ReactNativeTagHandles.js b/src/renderers/native/ReactNativeTagHandles.js
index 51e54d4033b..bcfa188ff86 100644
--- a/src/renderers/native/ReactNativeTagHandles.js
+++ b/src/renderers/native/ReactNativeTagHandles.js
@@ -11,7 +11,7 @@
  */
 'use strict';
 
-var invariant = require('fbjs/lib/invariant');
+import invariant from 'fbjs/lib/invariant';
 
 /**
  * Keeps track of allocating and associating native "tags" which are numeric,
@@ -27,32 +27,29 @@ var invariant = require('fbjs/lib/invariant');
  * unmount a component with a `rootNodeID`, then mount a new one in its place,
  */
 var INITIAL_TAG_COUNT = 1;
-var ReactNativeTagHandles = {
-  tagsStartAt: INITIAL_TAG_COUNT,
-  tagCount: INITIAL_TAG_COUNT,
 
-  allocateTag: function(): number {
-    // Skip over root IDs as those are reserved for native
-    while (this.reactTagIsNativeTopRootID(ReactNativeTagHandles.tagCount)) {
-      ReactNativeTagHandles.tagCount++;
-    }
-    var tag = ReactNativeTagHandles.tagCount;
-    ReactNativeTagHandles.tagCount++;
-    return tag;
-  },
+let tagCount = INITIAL_TAG_COUNT;
+export const tagsStartAt = INITIAL_TAG_COUNT;
 
-  assertRootTag: function(tag: number): void {
-    invariant(
-      this.reactTagIsNativeTopRootID(tag),
-      'Expect a native root tag, instead got %s',
-      tag,
-    );
-  },
+export function allocateTag(): number {
+  // Skip over root IDs as those are reserved for native
+  while (reactTagIsNativeTopRootID(tagCount)) {
+    tagCount++;
+  }
+  var tag = tagCount;
+  tagCount++;
+  return tag;
+}
 
-  reactTagIsNativeTopRootID: function(reactTag: number): boolean {
-    // We reserve all tags that are 1 mod 10 for native root views
-    return reactTag % 10 === 1;
-  },
-};
+export function assertRootTag(tag: number): void {
+  invariant(
+    reactTagIsNativeTopRootID(tag),
+    'Expect a native root tag, instead got %s',
+    tag,
+  );
+}
 
-module.exports = ReactNativeTagHandles;
+export function reactTagIsNativeTopRootID(reactTag: number): boolean {
+  // We reserve all tags that are 1 mod 10 for native root views
+  return reactTag % 10 === 1;
+}
diff --git a/src/renderers/native/ReactNativeViewConfigRegistry.js b/src/renderers/native/ReactNativeViewConfigRegistry.js
index fa6d379924e..01c012d542f 100644
--- a/src/renderers/native/ReactNativeViewConfigRegistry.js
+++ b/src/renderers/native/ReactNativeViewConfigRegistry.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-const invariant = require('fbjs/lib/invariant');
+import invariant from 'fbjs/lib/invariant';
 
 export type ReactNativeBaseComponentViewConfig = {
   validAttributes: Object,
@@ -22,22 +22,18 @@ export type ReactNativeBaseComponentViewConfig = {
 
 const viewConfigs = new Map();
 
-const ReactNativeViewConfigRegistry = {
-  register(viewConfig: ReactNativeBaseComponentViewConfig) {
-    const name = viewConfig.uiViewClassName;
-    invariant(
-      !viewConfigs.has(name),
-      'Tried to register two views with the same name %s',
-      name,
-    );
-    viewConfigs.set(name, viewConfig);
-    return name;
-  },
-  get(name: string) {
-    const config = viewConfigs.get(name);
-    invariant(config, 'View config not found for name %s', name);
-    return config;
-  },
-};
-
-module.exports = ReactNativeViewConfigRegistry;
+export function register(viewConfig: ReactNativeBaseComponentViewConfig) {
+  const name = viewConfig.uiViewClassName;
+  invariant(
+    !viewConfigs.has(name),
+    'Tried to register two views with the same name %s',
+    name,
+  );
+  viewConfigs.set(name, viewConfig);
+  return name;
+}
+export function get(name: string) {
+  const config = viewConfigs.get(name);
+  invariant(config, 'View config not found for name %s', name);
+  return config;
+}
diff --git a/src/renderers/shared/stack/__tests__/PooledClass-test.js b/src/renderers/native/__tests__/PooledClass-test.js
similarity index 100%
rename from src/renderers/shared/stack/__tests__/PooledClass-test.js
rename to src/renderers/native/__tests__/PooledClass-test.js
diff --git a/src/renderers/native/__tests__/ReactNativeEvents-test.js b/src/renderers/native/__tests__/ReactNativeEvents-test.js
index 5a43e47c8df..600609564ec 100644
--- a/src/renderers/native/__tests__/ReactNativeEvents-test.js
+++ b/src/renderers/native/__tests__/ReactNativeEvents-test.js
@@ -195,9 +195,7 @@ it('handles when a responder is unmounted while a touch sequence is in progress'
     if (responder === null) {
       return null;
     }
-    const props = typeof responder.tag === 'number'
-      ? responder.memoizedProps
-      : responder._currentElement.props;
+    const props = responder.memoizedProps;
     return props ? props.id : null;
   }
 
@@ -289,9 +287,7 @@ it('handles events without target', () => {
     if (responder === null) {
       return null;
     }
-    const props = typeof responder.tag === 'number'
-      ? responder.memoizedProps
-      : responder._currentElement.props;
+    const props = responder.memoizedProps;
     return props ? props.id : null;
   }
 
diff --git a/src/renderers/native/createReactNativeComponentClass.js b/src/renderers/native/createReactNativeComponentClass.js
index 3742475902d..28137f445ac 100644
--- a/src/renderers/native/createReactNativeComponentClass.js
+++ b/src/renderers/native/createReactNativeComponentClass.js
@@ -12,7 +12,9 @@
 
 'use strict';
 
-const ReactNativeViewConfigRegistry = require('ReactNativeViewConfigRegistry');
+import {
+  register as registerInViewConfigRegistry,
+} from 'ReactNativeViewConfigRegistry';
 
 // See also ReactNativeBaseComponent
 export type ReactNativeBaseComponentViewConfig = {
@@ -28,7 +30,7 @@ export type ReactNativeBaseComponentViewConfig = {
 const createReactNativeComponentClass = function(
   viewConfig: ReactNativeBaseComponentViewConfig,
 ): string {
-  return ReactNativeViewConfigRegistry.register(viewConfig);
+  return registerInViewConfigRegistry(viewConfig);
 };
 
-module.exports = createReactNativeComponentClass;
+export default createReactNativeComponentClass;
diff --git a/src/renderers/native/findNodeHandle.js b/src/renderers/native/findNodeHandle.js
index 75bb5ce6b16..b5ff66ab6bd 100644
--- a/src/renderers/native/findNodeHandle.js
+++ b/src/renderers/native/findNodeHandle.js
@@ -12,15 +12,12 @@
 
 'use strict';
 
-var ReactInstanceMap = require('ReactInstanceMap');
-var ReactNativeFiberRenderer = require('ReactNativeFiberRenderer');
-var {ReactCurrentOwner} = require('ReactGlobalSharedState');
-var getComponentName = require('getComponentName');
-var invariant = require('fbjs/lib/invariant');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import ReactInstanceMap from 'ReactInstanceMap';
+import ReactNativeFiberRenderer from 'ReactNativeFiberRenderer';
+import {ReactCurrentOwner} from 'ReactGlobalSharedState';
+import getComponentName from 'getComponentName';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
 
 import type {Fiber} from 'ReactFiber';
 
@@ -112,4 +109,4 @@ function findNodeHandle(componentOrHandle: any): any {
   }
 }
 
-module.exports = findNodeHandle;
+export default findNodeHandle;
diff --git a/src/renderers/native/findNumericNodeHandle.js b/src/renderers/native/findNumericNodeHandle.js
index f46bd18a0ef..17637f5daac 100644
--- a/src/renderers/native/findNumericNodeHandle.js
+++ b/src/renderers/native/findNumericNodeHandle.js
@@ -11,14 +11,14 @@
  */
 'use strict';
 
-var findNodeHandle = require('findNodeHandle');
+import findNodeHandle from 'findNodeHandle';
 
 /**
  * External users of findNodeHandle() expect the host tag number return type.
  * The injected findNodeHandle() strategy returns the instance wrapper though.
  * See NativeMethodsMixin#setNativeProps for more info on why this is done.
  */
-module.exports = function findNumericNodeHandleFiber(
+export default function findNumericNodeHandleFiber(
   componentOrHandle: any,
 ): ?number {
   const instance: any = findNodeHandle(componentOrHandle);
@@ -26,4 +26,4 @@ module.exports = function findNumericNodeHandleFiber(
     return instance;
   }
   return instance._nativeTag;
-};
+}
diff --git a/src/renderers/native/takeSnapshot.js b/src/renderers/native/takeSnapshot.js
index 5fa0df2028c..8afbe40ef5d 100644
--- a/src/renderers/native/takeSnapshot.js
+++ b/src/renderers/native/takeSnapshot.js
@@ -11,9 +11,9 @@
  */
 'use strict';
 
-const UIManager = require('UIManager');
+import UIManager from 'UIManager';
 
-const findNumericNodeHandle = require('findNumericNodeHandle');
+import findNumericNodeHandle from 'findNumericNodeHandle';
 
 /**
  * Capture an image of the screen, window or an individual view. The image
@@ -32,7 +32,7 @@ const findNumericNodeHandle = require('findNumericNodeHandle');
  * Returns a Promise.
  * @platform ios
  */
-function takeSnapshot(
+export default function takeSnapshot(
   view?: 'window' | ReactElement<any> | number,
   options?: {
     width?: number,
@@ -49,5 +49,3 @@ function takeSnapshot(
   // prevent accidental backwards-incompatible usage.
   return UIManager.__takeSnapshot(view, options);
 }
-
-module.exports = takeSnapshot;
diff --git a/src/renderers/noop/ReactNoopEntry.js b/src/renderers/noop/ReactNoopEntry.js
index bd9a21d1245..c71c70d38e2 100644
--- a/src/renderers/noop/ReactNoopEntry.js
+++ b/src/renderers/noop/ReactNoopEntry.js
@@ -22,13 +22,13 @@
 import type {Fiber} from 'ReactFiber';
 import type {UpdateQueue} from 'ReactFiberUpdateQueue';
 
-var ReactFiberInstrumentation = require('ReactFiberInstrumentation');
-var ReactFiberReconciler = require('ReactFiberReconciler');
-var ReactInstanceMap = require('ReactInstanceMap');
-var {TaskPriority} = require('ReactPriorityLevel');
-var emptyObject = require('fbjs/lib/emptyObject');
+import ReactFiberInstrumentation from 'ReactFiberInstrumentation';
+import ReactFiberReconciler from 'ReactFiberReconciler';
+import ReactInstanceMap from 'ReactInstanceMap';
+import {TaskPriority} from 'ReactPriorityLevel';
+import emptyObject from 'fbjs/lib/emptyObject';
 
-var expect = require('jest-matchers');
+import expect from 'jest-matchers';
 
 const UPDATE_SIGNAL = {};
 
@@ -474,4 +474,6 @@ var ReactNoop = {
   },
 };
 
+// TODO: this fixes Rollup build but probably breaks Jest.
+// Need to figure something out.
 module.exports = ReactNoop;
diff --git a/src/renderers/shared/ReactDOMFrameScheduling.js b/src/renderers/shared/ReactDOMFrameScheduling.js
index a7023349666..852b31dc565 100644
--- a/src/renderers/shared/ReactDOMFrameScheduling.js
+++ b/src/renderers/shared/ReactDOMFrameScheduling.js
@@ -22,11 +22,10 @@
 
 import type {Deadline} from 'ReactFiberReconciler';
 
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
+import ExecutionEnvironment from 'fbjs/lib/ExecutionEnvironment';
+import warning from 'fbjs/lib/warning';
 
 if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-
   if (
     ExecutionEnvironment.canUseDOM &&
     typeof requestAnimationFrame !== 'function'
@@ -40,7 +39,7 @@ if (__DEV__) {
 }
 
 // TODO: There's no way to cancel, because Fiber doesn't atm.
-let rIC: (callback: (deadline: Deadline) => void) => number;
+export let rIC: (callback: (deadline: Deadline) => void) => number;
 
 if (!ExecutionEnvironment.canUseDOM) {
   rIC = function(frameCallback: (deadline: Deadline) => void): number {
@@ -154,5 +153,3 @@ if (!ExecutionEnvironment.canUseDOM) {
 } else {
   rIC = requestIdleCallback;
 }
-
-exports.rIC = rIC;
diff --git a/src/renderers/shared/ReactDebugTool.js b/src/renderers/shared/ReactDebugTool.js
deleted file mode 100644
index 2b212d37a19..00000000000
--- a/src/renderers/shared/ReactDebugTool.js
+++ /dev/null
@@ -1,441 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDebugTool
- * @flow
- */
-
-'use strict';
-
-var ReactInvalidSetStateWarningHook = require('ReactInvalidSetStateWarningHook');
-var ReactHostOperationHistoryHook = require('ReactHostOperationHistoryHook');
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
-var {ReactComponentTreeHook} = require('ReactGlobalSharedState');
-
-var performanceNow = require('fbjs/lib/performanceNow');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
-import type {ReactElement} from 'ReactElementType';
-import type {DebugID} from 'ReactInstanceType';
-import type {Operation} from 'ReactHostOperationHistoryHook';
-
-type Hook = any;
-
-type TimerType =
-  | 'ctor'
-  | 'render'
-  | 'componentWillMount'
-  | 'componentWillUnmount'
-  | 'componentWillReceiveProps'
-  | 'shouldComponentUpdate'
-  | 'componentWillUpdate'
-  | 'componentDidUpdate'
-  | 'componentDidMount';
-
-type Measurement = {
-  timerType: TimerType,
-  instanceID: DebugID,
-  duration: number,
-};
-
-type TreeSnapshot = {
-  [key: DebugID]: {
-    displayName: string,
-    text: string,
-    updateCount: number,
-    childIDs: Array<DebugID>,
-    ownerID: DebugID,
-    parentID: DebugID,
-  },
-};
-
-type HistoryItem = {
-  duration: number,
-  measurements: Array<Measurement>,
-  operations: Array<Operation>,
-  treeSnapshot: TreeSnapshot,
-};
-
-export type FlushHistory = Array<HistoryItem>;
-
-// Trust the developer to only use this with a __DEV__ check
-var ReactDebugTool = ((null: any): typeof ReactDebugTool);
-
-if (__DEV__) {
-  var hooks = [];
-  var didHookThrowForEvent = {};
-
-  const callHook = function(event, fn, context, arg1, arg2, arg3, arg4, arg5) {
-    try {
-      fn.call(context, arg1, arg2, arg3, arg4, arg5);
-    } catch (e) {
-      warning(
-        didHookThrowForEvent[event],
-        'Exception thrown by hook while handling %s: %s',
-        event,
-        e + '\n' + e.stack,
-      );
-      didHookThrowForEvent[event] = true;
-    }
-  };
-
-  const emitEvent = function(event, arg1, arg2, arg3, arg4, arg5) {
-    for (var i = 0; i < hooks.length; i++) {
-      var hook = hooks[i];
-      var fn = hook[event];
-      if (fn) {
-        callHook(event, fn, hook, arg1, arg2, arg3, arg4, arg5);
-      }
-    }
-  };
-
-  var isProfiling = false;
-  var flushHistory = [];
-  var lifeCycleTimerStack = [];
-  var currentFlushNesting = 0;
-  var currentFlushMeasurements = [];
-  var currentFlushStartTime = 0;
-  var currentTimerDebugID = null;
-  var currentTimerStartTime = 0;
-  var currentTimerNestedFlushDuration = 0;
-  var currentTimerType = null;
-
-  var lifeCycleTimerHasWarned = false;
-
-  const clearHistory = function() {
-    ReactComponentTreeHook.purgeUnmountedComponents();
-    ReactHostOperationHistoryHook.clearHistory();
-  };
-
-  const getTreeSnapshot = function(registeredIDs) {
-    return registeredIDs.reduce((tree, id) => {
-      var ownerID = ReactComponentTreeHook.getOwnerID(id);
-      var parentID = ReactComponentTreeHook.getParentID(id);
-      tree[id] = {
-        displayName: ReactComponentTreeHook.getDisplayName(id),
-        text: ReactComponentTreeHook.getText(id),
-        updateCount: ReactComponentTreeHook.getUpdateCount(id),
-        childIDs: ReactComponentTreeHook.getChildIDs(id),
-        // Text nodes don't have owners but this is close enough.
-        ownerID: ownerID ||
-          (parentID && ReactComponentTreeHook.getOwnerID(parentID)) ||
-          0,
-        parentID,
-      };
-      return tree;
-    }, {});
-  };
-
-  const resetMeasurements = function() {
-    var previousStartTime = currentFlushStartTime;
-    var previousMeasurements = currentFlushMeasurements;
-    var previousOperations = ReactHostOperationHistoryHook.getHistory();
-
-    if (currentFlushNesting === 0) {
-      currentFlushStartTime = 0;
-      currentFlushMeasurements = [];
-      clearHistory();
-      return;
-    }
-
-    if (previousMeasurements.length || previousOperations.length) {
-      var registeredIDs = ReactComponentTreeHook.getRegisteredIDs();
-      flushHistory.push({
-        duration: performanceNow() - previousStartTime,
-        measurements: previousMeasurements || [],
-        operations: previousOperations || [],
-        treeSnapshot: getTreeSnapshot(registeredIDs),
-      });
-    }
-
-    clearHistory();
-    currentFlushStartTime = performanceNow();
-    currentFlushMeasurements = [];
-  };
-
-  const checkDebugID = function(debugID, allowRoot = false) {
-    if (allowRoot && debugID === 0) {
-      return;
-    }
-    if (!debugID) {
-      warning(false, 'ReactDebugTool: debugID may not be empty.');
-    }
-  };
-
-  const beginLifeCycleTimer = function(debugID, timerType) {
-    if (currentFlushNesting === 0) {
-      return;
-    }
-    if (currentTimerType && !lifeCycleTimerHasWarned) {
-      warning(
-        false,
-        'There is an internal error in the React performance measurement code.' +
-          '\n\nDid not expect %s timer to start while %s timer is still in ' +
-          'progress for %s instance.',
-        timerType,
-        currentTimerType || 'no',
-        debugID === currentTimerDebugID ? 'the same' : 'another',
-      );
-      lifeCycleTimerHasWarned = true;
-    }
-    currentTimerStartTime = performanceNow();
-    currentTimerNestedFlushDuration = 0;
-    currentTimerDebugID = debugID;
-    currentTimerType = timerType;
-  };
-
-  const endLifeCycleTimer = function(debugID, timerType) {
-    if (currentFlushNesting === 0) {
-      return;
-    }
-    if (currentTimerType !== timerType && !lifeCycleTimerHasWarned) {
-      warning(
-        false,
-        'There is an internal error in the React performance measurement code. ' +
-          'We did not expect %s timer to stop while %s timer is still in ' +
-          'progress for %s instance. Please report this as a bug in React.',
-        timerType,
-        currentTimerType || 'no',
-        debugID === currentTimerDebugID ? 'the same' : 'another',
-      );
-      lifeCycleTimerHasWarned = true;
-    }
-    if (isProfiling) {
-      currentFlushMeasurements.push({
-        timerType,
-        instanceID: debugID,
-        duration: performanceNow() -
-          currentTimerStartTime -
-          currentTimerNestedFlushDuration,
-      });
-    }
-    currentTimerStartTime = 0;
-    currentTimerNestedFlushDuration = 0;
-    currentTimerDebugID = null;
-    currentTimerType = null;
-  };
-
-  const pauseCurrentLifeCycleTimer = function() {
-    var currentTimer = {
-      startTime: currentTimerStartTime,
-      nestedFlushStartTime: performanceNow(),
-      debugID: currentTimerDebugID,
-      timerType: currentTimerType,
-    };
-    lifeCycleTimerStack.push(currentTimer);
-    currentTimerStartTime = 0;
-    currentTimerNestedFlushDuration = 0;
-    currentTimerDebugID = null;
-    currentTimerType = null;
-  };
-
-  const resumeCurrentLifeCycleTimer = function() {
-    var {
-      startTime,
-      nestedFlushStartTime,
-      debugID,
-      timerType,
-    } = lifeCycleTimerStack.pop();
-    var nestedFlushDuration = performanceNow() - nestedFlushStartTime;
-    currentTimerStartTime = startTime;
-    currentTimerNestedFlushDuration += nestedFlushDuration;
-    currentTimerDebugID = debugID;
-    currentTimerType = timerType;
-  };
-
-  var lastMarkTimeStamp = 0;
-  var canUsePerformanceMeasure: boolean =
-    typeof performance !== 'undefined' &&
-    typeof performance.mark === 'function' &&
-    typeof performance.clearMarks === 'function' &&
-    typeof performance.measure === 'function' &&
-    typeof performance.clearMeasures === 'function';
-
-  const shouldMark = function(debugID) {
-    if (!isProfiling || !canUsePerformanceMeasure) {
-      return false;
-    }
-    var element = ReactComponentTreeHook.getElement(debugID);
-    if (element == null || typeof element !== 'object') {
-      return false;
-    }
-    var isHostElement = typeof element.type === 'string';
-    if (isHostElement) {
-      return false;
-    }
-    return true;
-  };
-
-  const markBegin = function(debugID, markType) {
-    if (!shouldMark(debugID)) {
-      return;
-    }
-
-    var markName = `${debugID}::${markType}`;
-    lastMarkTimeStamp = performanceNow();
-    performance.mark(markName);
-  };
-
-  const markEnd = function(debugID, markType) {
-    if (!shouldMark(debugID)) {
-      return;
-    }
-
-    var markName = `${debugID}::${markType}`;
-    var displayName =
-      ReactComponentTreeHook.getDisplayName(debugID) || 'Unknown';
-
-    // Chrome has an issue of dropping markers recorded too fast:
-    // https://bugs.chromium.org/p/chromium/issues/detail?id=640652
-    // To work around this, we will not report very small measurements.
-    // I determined the magic number by tweaking it back and forth.
-    // 0.05ms was enough to prevent the issue, but I set it to 0.1ms to be safe.
-    // When the bug is fixed, we can `measure()` unconditionally if we want to.
-    var timeStamp = performanceNow();
-    if (timeStamp - lastMarkTimeStamp > 0.1) {
-      var measurementName = `${displayName} [${markType}]`;
-      performance.measure(measurementName, markName);
-    }
-
-    performance.clearMarks(markName);
-    if (measurementName) {
-      performance.clearMeasures(measurementName);
-    }
-  };
-
-  ReactDebugTool = {
-    addHook(hook: Hook): void {
-      hooks.push(hook);
-    },
-    removeHook(hook: Hook): void {
-      for (var i = 0; i < hooks.length; i++) {
-        if (hooks[i] === hook) {
-          hooks.splice(i, 1);
-          i--;
-        }
-      }
-    },
-    isProfiling(): boolean {
-      return isProfiling;
-    },
-    beginProfiling(): void {
-      if (isProfiling) {
-        return;
-      }
-
-      isProfiling = true;
-      flushHistory.length = 0;
-      resetMeasurements();
-      ReactDebugTool.addHook(ReactHostOperationHistoryHook);
-    },
-    endProfiling(): void {
-      if (!isProfiling) {
-        return;
-      }
-
-      isProfiling = false;
-      resetMeasurements();
-      ReactDebugTool.removeHook(ReactHostOperationHistoryHook);
-    },
-    getFlushHistory(): FlushHistory {
-      return flushHistory;
-    },
-    onBeginFlush(): void {
-      currentFlushNesting++;
-      resetMeasurements();
-      pauseCurrentLifeCycleTimer();
-      emitEvent('onBeginFlush');
-    },
-    onEndFlush(): void {
-      resetMeasurements();
-      currentFlushNesting--;
-      resumeCurrentLifeCycleTimer();
-      emitEvent('onEndFlush');
-    },
-    onBeginLifeCycleTimer(debugID: DebugID, timerType: TimerType): void {
-      checkDebugID(debugID);
-      emitEvent('onBeginLifeCycleTimer', debugID, timerType);
-      markBegin(debugID, timerType);
-      beginLifeCycleTimer(debugID, timerType);
-    },
-    onEndLifeCycleTimer(debugID: DebugID, timerType: TimerType): void {
-      checkDebugID(debugID);
-      endLifeCycleTimer(debugID, timerType);
-      markEnd(debugID, timerType);
-      emitEvent('onEndLifeCycleTimer', debugID, timerType);
-    },
-    onBeginProcessingChildContext(): void {
-      emitEvent('onBeginProcessingChildContext');
-    },
-    onEndProcessingChildContext(): void {
-      emitEvent('onEndProcessingChildContext');
-    },
-    onHostOperation(operation: Operation) {
-      checkDebugID(operation.instanceID);
-      emitEvent('onHostOperation', operation);
-    },
-    onSetState(): void {
-      emitEvent('onSetState');
-    },
-    onSetChildren(debugID: DebugID, childDebugIDs: Array<DebugID>) {
-      checkDebugID(debugID);
-      childDebugIDs.forEach(checkDebugID);
-      emitEvent('onSetChildren', debugID, childDebugIDs);
-    },
-    onBeforeMountComponent(
-      debugID: DebugID,
-      element: ReactElement,
-      parentDebugID: DebugID,
-    ): void {
-      checkDebugID(debugID);
-      checkDebugID(parentDebugID, true);
-      emitEvent('onBeforeMountComponent', debugID, element, parentDebugID);
-      markBegin(debugID, 'mount');
-    },
-    onMountComponent(debugID: DebugID): void {
-      checkDebugID(debugID);
-      markEnd(debugID, 'mount');
-      emitEvent('onMountComponent', debugID);
-    },
-    onBeforeUpdateComponent(debugID: DebugID, element: ReactElement): void {
-      checkDebugID(debugID);
-      emitEvent('onBeforeUpdateComponent', debugID, element);
-      markBegin(debugID, 'update');
-    },
-    onUpdateComponent(debugID: DebugID): void {
-      checkDebugID(debugID);
-      markEnd(debugID, 'update');
-      emitEvent('onUpdateComponent', debugID);
-    },
-    onBeforeUnmountComponent(debugID: DebugID): void {
-      checkDebugID(debugID);
-      emitEvent('onBeforeUnmountComponent', debugID);
-      markBegin(debugID, 'unmount');
-    },
-    onUnmountComponent(debugID: DebugID): void {
-      checkDebugID(debugID);
-      markEnd(debugID, 'unmount');
-      emitEvent('onUnmountComponent', debugID);
-    },
-    onTestEvent(): void {
-      emitEvent('onTestEvent');
-    },
-  };
-
-  ReactDebugTool.addHook(ReactInvalidSetStateWarningHook);
-  ReactDebugTool.addHook(ReactComponentTreeHook);
-  var url = (ExecutionEnvironment.canUseDOM && window.location.href) || '';
-  if (/[?&]react_perf\b/.test(url)) {
-    ReactDebugTool.beginProfiling();
-  }
-}
-
-module.exports = ReactDebugTool;
diff --git a/src/renderers/shared/ReactGlobalSharedState.js b/src/renderers/shared/ReactGlobalSharedState.js
index 42e9d9bc011..808570b595d 100644
--- a/src/renderers/shared/ReactGlobalSharedState.js
+++ b/src/renderers/shared/ReactGlobalSharedState.js
@@ -11,18 +11,9 @@
 
 'use strict';
 
-var ReactInternals = require('react')
-  .__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED;
+import React from 'react';
+var ReactInternals = React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED;
 
-var ReactGlobalSharedState = {
-  ReactCurrentOwner: ReactInternals.ReactCurrentOwner,
-};
-
-if (__DEV__) {
-  Object.assign(ReactGlobalSharedState, {
-    ReactComponentTreeHook: ReactInternals.ReactComponentTreeHook,
-    ReactDebugCurrentFrame: ReactInternals.ReactDebugCurrentFrame,
-  });
-}
-
-module.exports = ReactGlobalSharedState;
+export const ReactCurrentOwner = ReactInternals.ReactCurrentOwner;
+// DEV-only:
+export const ReactDebugCurrentFrame = ReactInternals.ReactDebugCurrentFrame;
diff --git a/src/renderers/shared/ReactInstrumentation.js b/src/renderers/shared/ReactInstrumentation.js
deleted file mode 100644
index a5de36d00ef..00000000000
--- a/src/renderers/shared/ReactInstrumentation.js
+++ /dev/null
@@ -1,23 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactInstrumentation
- * @flow
- */
-
-'use strict';
-
-// Trust the developer to only use ReactInstrumentation with a __DEV__ check
-var debugTool = ((null: any): typeof ReactDebugTool);
-
-if (__DEV__) {
-  var ReactDebugTool = require('ReactDebugTool');
-  debugTool = ReactDebugTool;
-}
-
-module.exports = {debugTool};
diff --git a/src/renderers/shared/ReactPerf.js b/src/renderers/shared/ReactPerf.js
deleted file mode 100644
index 17abb58095e..00000000000
--- a/src/renderers/shared/ReactPerf.js
+++ /dev/null
@@ -1,458 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactPerf
- * @flow
- */
-
-'use strict';
-
-var ReactDebugTool = require('ReactDebugTool');
-var lowPriorityWarning = require('lowPriorityWarning');
-var alreadyWarned = false;
-
-import type {FlushHistory} from 'ReactDebugTool';
-
-function roundFloat(val, base = 2) {
-  var n = Math.pow(10, base);
-  return Math.floor(val * n) / n;
-}
-
-// Flow type definition of console.table is too strict right now, see
-// https://github.com/facebook/flow/pull/2353 for updates
-function consoleTable(table: Array<{[key: string]: any}>): void {
-  console.table((table: any));
-}
-
-function warnInProduction() {
-  if (alreadyWarned) {
-    return;
-  }
-  alreadyWarned = true;
-  if (typeof console !== 'undefined') {
-    console.error(
-      'ReactPerf is not supported in the production builds of React. ' +
-        'To collect measurements, please use the development build of React instead.',
-    );
-  }
-}
-
-function getLastMeasurements() {
-  if (!__DEV__) {
-    warnInProduction();
-    return [];
-  }
-
-  return ReactDebugTool.getFlushHistory();
-}
-
-function getExclusive(flushHistory = getLastMeasurements()) {
-  if (!__DEV__) {
-    warnInProduction();
-    return [];
-  }
-
-  var aggregatedStats = {};
-  var affectedIDs = {};
-
-  function updateAggregatedStats(
-    treeSnapshot,
-    instanceID,
-    timerType,
-    applyUpdate,
-  ) {
-    var {displayName} = treeSnapshot[instanceID];
-    var key = displayName;
-    var stats = aggregatedStats[key];
-    if (!stats) {
-      affectedIDs[key] = {};
-      stats = aggregatedStats[key] = {
-        key,
-        instanceCount: 0,
-        counts: {},
-        durations: {},
-        totalDuration: 0,
-      };
-    }
-    if (!stats.durations[timerType]) {
-      stats.durations[timerType] = 0;
-    }
-    if (!stats.counts[timerType]) {
-      stats.counts[timerType] = 0;
-    }
-    affectedIDs[key][instanceID] = true;
-    applyUpdate(stats);
-  }
-
-  flushHistory.forEach(flush => {
-    var {measurements, treeSnapshot} = flush;
-    measurements.forEach(measurement => {
-      var {duration, instanceID, timerType} = measurement;
-      updateAggregatedStats(treeSnapshot, instanceID, timerType, stats => {
-        stats.totalDuration += duration;
-        stats.durations[timerType] += duration;
-        stats.counts[timerType]++;
-      });
-    });
-  });
-
-  return Object.keys(aggregatedStats)
-    .map(key => ({
-      ...aggregatedStats[key],
-      instanceCount: Object.keys(affectedIDs[key]).length,
-    }))
-    .sort((a, b) => b.totalDuration - a.totalDuration);
-}
-
-function getInclusive(flushHistory = getLastMeasurements()) {
-  if (!__DEV__) {
-    warnInProduction();
-    return [];
-  }
-
-  var aggregatedStats = {};
-  var affectedIDs = {};
-
-  function updateAggregatedStats(treeSnapshot, instanceID, applyUpdate) {
-    var {displayName, ownerID} = treeSnapshot[instanceID];
-    var owner = treeSnapshot[ownerID];
-    var key = (owner ? owner.displayName + ' > ' : '') + displayName;
-    var stats = aggregatedStats[key];
-    if (!stats) {
-      affectedIDs[key] = {};
-      stats = aggregatedStats[key] = {
-        key,
-        instanceCount: 0,
-        inclusiveRenderDuration: 0,
-        renderCount: 0,
-      };
-    }
-    affectedIDs[key][instanceID] = true;
-    applyUpdate(stats);
-  }
-
-  var isCompositeByID = {};
-  flushHistory.forEach(flush => {
-    var {measurements} = flush;
-    measurements.forEach(measurement => {
-      var {instanceID, timerType} = measurement;
-      if (timerType !== 'render') {
-        return;
-      }
-      isCompositeByID[instanceID] = true;
-    });
-  });
-
-  flushHistory.forEach(flush => {
-    var {measurements, treeSnapshot} = flush;
-    measurements.forEach(measurement => {
-      var {duration, instanceID, timerType} = measurement;
-      if (timerType !== 'render') {
-        return;
-      }
-      updateAggregatedStats(treeSnapshot, instanceID, stats => {
-        stats.renderCount++;
-      });
-      var nextParentID = instanceID;
-      while (nextParentID) {
-        // As we traverse parents, only count inclusive time towards composites.
-        // We know something is a composite if its render() was called.
-        if (isCompositeByID[nextParentID]) {
-          updateAggregatedStats(treeSnapshot, nextParentID, stats => {
-            stats.inclusiveRenderDuration += duration;
-          });
-        }
-        nextParentID = treeSnapshot[nextParentID].parentID;
-      }
-    });
-  });
-
-  return Object.keys(aggregatedStats)
-    .map(key => ({
-      ...aggregatedStats[key],
-      instanceCount: Object.keys(affectedIDs[key]).length,
-    }))
-    .sort((a, b) => b.inclusiveRenderDuration - a.inclusiveRenderDuration);
-}
-
-function getWasted(flushHistory = getLastMeasurements()) {
-  if (!__DEV__) {
-    warnInProduction();
-    return [];
-  }
-
-  var aggregatedStats = {};
-  var affectedIDs = {};
-
-  function updateAggregatedStats(treeSnapshot, instanceID, applyUpdate) {
-    var {displayName, ownerID} = treeSnapshot[instanceID];
-    var owner = treeSnapshot[ownerID];
-    var key = (owner ? owner.displayName + ' > ' : '') + displayName;
-    var stats = aggregatedStats[key];
-    if (!stats) {
-      affectedIDs[key] = {};
-      stats = aggregatedStats[key] = {
-        key,
-        instanceCount: 0,
-        inclusiveRenderDuration: 0,
-        renderCount: 0,
-      };
-    }
-    affectedIDs[key][instanceID] = true;
-    applyUpdate(stats);
-  }
-
-  flushHistory.forEach(flush => {
-    var {measurements, treeSnapshot, operations} = flush;
-    var isDefinitelyNotWastedByID = {};
-
-    // Find host components associated with an operation in this batch.
-    // Mark all components in their parent tree as definitely not wasted.
-    operations.forEach(operation => {
-      var {instanceID} = operation;
-      var nextParentID = instanceID;
-      while (nextParentID) {
-        isDefinitelyNotWastedByID[nextParentID] = true;
-        nextParentID = treeSnapshot[nextParentID].parentID;
-      }
-    });
-
-    // Find composite components that rendered in this batch.
-    // These are potential candidates for being wasted renders.
-    var renderedCompositeIDs = {};
-    measurements.forEach(measurement => {
-      var {instanceID, timerType} = measurement;
-      if (timerType !== 'render') {
-        return;
-      }
-      renderedCompositeIDs[instanceID] = true;
-    });
-
-    measurements.forEach(measurement => {
-      var {duration, instanceID, timerType} = measurement;
-      if (timerType !== 'render') {
-        return;
-      }
-
-      // If there was a DOM update below this component, or it has just been
-      // mounted, its render() is not considered wasted.
-      var {updateCount} = treeSnapshot[instanceID];
-      if (isDefinitelyNotWastedByID[instanceID] || updateCount === 0) {
-        return;
-      }
-
-      // We consider this render() wasted.
-      updateAggregatedStats(treeSnapshot, instanceID, stats => {
-        stats.renderCount++;
-      });
-
-      var nextParentID = instanceID;
-      while (nextParentID) {
-        // Any parents rendered during this batch are considered wasted
-        // unless we previously marked them as dirty.
-        var isWasted =
-          renderedCompositeIDs[nextParentID] &&
-          !isDefinitelyNotWastedByID[nextParentID];
-        if (isWasted) {
-          updateAggregatedStats(treeSnapshot, nextParentID, stats => {
-            stats.inclusiveRenderDuration += duration;
-          });
-        }
-        nextParentID = treeSnapshot[nextParentID].parentID;
-      }
-    });
-  });
-
-  return Object.keys(aggregatedStats)
-    .map(key => ({
-      ...aggregatedStats[key],
-      instanceCount: Object.keys(affectedIDs[key]).length,
-    }))
-    .sort((a, b) => b.inclusiveRenderDuration - a.inclusiveRenderDuration);
-}
-
-function getOperations(flushHistory = getLastMeasurements()) {
-  if (!__DEV__) {
-    warnInProduction();
-    return [];
-  }
-
-  var stats = [];
-  flushHistory.forEach((flush, flushIndex) => {
-    var {operations, treeSnapshot} = flush;
-    operations.forEach(operation => {
-      var {instanceID, type, payload} = operation;
-      var {displayName, ownerID} = treeSnapshot[instanceID];
-      var owner = treeSnapshot[ownerID];
-      var key = (owner ? owner.displayName + ' > ' : '') + displayName;
-
-      stats.push({
-        flushIndex,
-        instanceID,
-        key,
-        type,
-        ownerID,
-        payload,
-      });
-    });
-  });
-  return stats;
-}
-
-function printExclusive(flushHistory?: FlushHistory) {
-  if (!__DEV__) {
-    warnInProduction();
-    return;
-  }
-
-  var stats = getExclusive(flushHistory);
-  var table = stats.map(item => {
-    var {key, instanceCount, totalDuration} = item;
-    var renderCount = item.counts.render || 0;
-    var renderDuration = item.durations.render || 0;
-    return {
-      Component: key,
-      'Total time (ms)': roundFloat(totalDuration),
-      'Instance count': instanceCount,
-      'Total render time (ms)': roundFloat(renderDuration),
-      'Average render time (ms)': renderCount
-        ? roundFloat(renderDuration / renderCount)
-        : undefined,
-      'Render count': renderCount,
-      'Total lifecycle time (ms)': roundFloat(totalDuration - renderDuration),
-    };
-  });
-  consoleTable(table);
-}
-
-function printInclusive(flushHistory?: FlushHistory) {
-  if (!__DEV__) {
-    warnInProduction();
-    return;
-  }
-
-  var stats = getInclusive(flushHistory);
-  var table = stats.map(item => {
-    var {key, instanceCount, inclusiveRenderDuration, renderCount} = item;
-    return {
-      'Owner > Component': key,
-      'Inclusive render time (ms)': roundFloat(inclusiveRenderDuration),
-      'Instance count': instanceCount,
-      'Render count': renderCount,
-    };
-  });
-  consoleTable(table);
-}
-
-function printWasted(flushHistory?: FlushHistory) {
-  if (!__DEV__) {
-    warnInProduction();
-    return;
-  }
-
-  var stats = getWasted(flushHistory);
-  var table = stats.map(item => {
-    var {key, instanceCount, inclusiveRenderDuration, renderCount} = item;
-    return {
-      'Owner > Component': key,
-      'Inclusive wasted time (ms)': roundFloat(inclusiveRenderDuration),
-      'Instance count': instanceCount,
-      'Render count': renderCount,
-    };
-  });
-  consoleTable(table);
-}
-
-function printOperations(flushHistory?: FlushHistory) {
-  if (!__DEV__) {
-    warnInProduction();
-    return;
-  }
-
-  var stats = getOperations(flushHistory);
-  var table = stats.map(stat => ({
-    'Owner > Node': stat.key,
-    Operation: stat.type,
-    Payload: typeof stat.payload === 'object'
-      ? JSON.stringify(stat.payload)
-      : stat.payload,
-    'Flush index': stat.flushIndex,
-    'Owner Component ID': stat.ownerID,
-    'DOM Component ID': stat.instanceID,
-  }));
-  consoleTable(table);
-}
-
-var warnedAboutPrintDOM = false;
-function printDOM(measurements: FlushHistory) {
-  lowPriorityWarning(
-    warnedAboutPrintDOM,
-    '`ReactPerf.printDOM(...)` is deprecated. Use ' +
-      '`ReactPerf.printOperations(...)` instead.',
-  );
-  warnedAboutPrintDOM = true;
-  return printOperations(measurements);
-}
-
-var warnedAboutGetMeasurementsSummaryMap = false;
-function getMeasurementsSummaryMap(measurements: FlushHistory) {
-  lowPriorityWarning(
-    warnedAboutGetMeasurementsSummaryMap,
-    '`ReactPerf.getMeasurementsSummaryMap(...)` is deprecated. Use ' +
-      '`ReactPerf.getWasted(...)` instead.',
-  );
-  warnedAboutGetMeasurementsSummaryMap = true;
-  return getWasted(measurements);
-}
-
-function start() {
-  if (!__DEV__) {
-    warnInProduction();
-    return;
-  }
-
-  ReactDebugTool.beginProfiling();
-}
-
-function stop() {
-  if (!__DEV__) {
-    warnInProduction();
-    return;
-  }
-
-  ReactDebugTool.endProfiling();
-}
-
-function isRunning() {
-  if (!__DEV__) {
-    warnInProduction();
-    return false;
-  }
-
-  return ReactDebugTool.isProfiling();
-}
-
-var ReactPerfAnalysis = {
-  getLastMeasurements,
-  getExclusive,
-  getInclusive,
-  getWasted,
-  getOperations,
-  printExclusive,
-  printInclusive,
-  printWasted,
-  printOperations,
-  start,
-  stop,
-  isRunning,
-  // Deprecated:
-  printDOM,
-  getMeasurementsSummaryMap,
-};
-
-module.exports = ReactPerfAnalysis;
diff --git a/src/renderers/shared/__tests__/ReactDOMFrameScheduling-test.js b/src/renderers/shared/__tests__/ReactDOMFrameScheduling-test.js
index 7b6949ca12f..ce40ecd9b39 100644
--- a/src/renderers/shared/__tests__/ReactDOMFrameScheduling-test.js
+++ b/src/renderers/shared/__tests__/ReactDOMFrameScheduling-test.js
@@ -11,10 +11,7 @@
 
 'use strict';
 
-const ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-const describeFiber = ReactDOMFeatureFlags.useFiber ? describe : xdescribe;
-
-describeFiber('ReactDOMFrameScheduling', () => {
+describe('ReactDOMFrameScheduling', () => {
   it('warns when requestAnimationFrame is not polyfilled in the browser', () => {
     const previousRAF = global.requestAnimationFrame;
     try {
diff --git a/src/renderers/shared/__tests__/ReactDebugTool-test.js b/src/renderers/shared/__tests__/ReactDebugTool-test.js
deleted file mode 100644
index 3082b9eab9e..00000000000
--- a/src/renderers/shared/__tests__/ReactDebugTool-test.js
+++ /dev/null
@@ -1,84 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @emails react-core
- */
-
-'use strict';
-
-describe('ReactDebugTool', () => {
-  var ReactDebugTool;
-
-  beforeEach(() => {
-    jest.resetModules();
-    ReactDebugTool = require('ReactDebugTool');
-  });
-
-  it('should add and remove hooks', () => {
-    var handler1 = jasmine.createSpy('spy');
-    var handler2 = jasmine.createSpy('spy');
-    var hook1 = {onTestEvent: handler1};
-    var hook2 = {onTestEvent: handler2};
-
-    ReactDebugTool.addHook(hook1);
-    ReactDebugTool.onTestEvent();
-    expect(handler1.calls.count()).toBe(1);
-    expect(handler2.calls.count()).toBe(0);
-
-    ReactDebugTool.onTestEvent();
-    expect(handler1.calls.count()).toBe(2);
-    expect(handler2.calls.count()).toBe(0);
-
-    ReactDebugTool.addHook(hook2);
-    ReactDebugTool.onTestEvent();
-    expect(handler1.calls.count()).toBe(3);
-    expect(handler2.calls.count()).toBe(1);
-
-    ReactDebugTool.onTestEvent();
-    expect(handler1.calls.count()).toBe(4);
-    expect(handler2.calls.count()).toBe(2);
-
-    ReactDebugTool.removeHook(hook1);
-    ReactDebugTool.onTestEvent();
-    expect(handler1.calls.count()).toBe(4);
-    expect(handler2.calls.count()).toBe(3);
-
-    ReactDebugTool.removeHook(hook2);
-    ReactDebugTool.onTestEvent();
-    expect(handler1.calls.count()).toBe(4);
-    expect(handler2.calls.count()).toBe(3);
-  });
-
-  it('warns once when an error is thrown in hook', () => {
-    spyOn(console, 'error');
-    ReactDebugTool.addHook({
-      onTestEvent() {
-        throw new Error('Hi.');
-      },
-    });
-
-    ReactDebugTool.onTestEvent();
-    expectDev(console.error.calls.count()).toBe(1);
-    expectDev(console.error.calls.argsFor(0)[0]).toContain(
-      'Exception thrown by hook while handling ' + 'onTestEvent: Error: Hi.',
-    );
-
-    ReactDebugTool.onTestEvent();
-    expectDev(console.error.calls.count()).toBe(1);
-  });
-
-  it('returns isProfiling state', () => {
-    expect(ReactDebugTool.isProfiling()).toBe(false);
-
-    ReactDebugTool.beginProfiling();
-    expect(ReactDebugTool.isProfiling()).toBe(true);
-
-    ReactDebugTool.endProfiling();
-    expect(ReactDebugTool.isProfiling()).toBe(false);
-  });
-});
diff --git a/src/renderers/shared/fiber/ReactChildFiber.js b/src/renderers/shared/fiber/ReactChildFiber.js
index 9a4157b13e9..c251cf0e243 100644
--- a/src/renderers/shared/fiber/ReactChildFiber.js
+++ b/src/renderers/shared/fiber/ReactChildFiber.js
@@ -15,23 +15,36 @@
 import type {ReactElement} from 'ReactElementType';
 import type {ReactCoroutine, ReactPortal, ReactYield} from 'ReactTypes';
 import type {Fiber} from 'ReactFiber';
-import type {ReactInstance} from 'ReactInstanceType';
 import type {PriorityLevel} from 'ReactPriorityLevel';
 
-var {REACT_COROUTINE_TYPE, REACT_YIELD_TYPE} = require('ReactCoroutine');
-var {REACT_PORTAL_TYPE} = require('ReactPortal');
-
-var ReactFiber = require('ReactFiber');
-var ReactTypeOfSideEffect = require('ReactTypeOfSideEffect');
-var ReactTypeOfWork = require('ReactTypeOfWork');
-
-var emptyObject = require('fbjs/lib/emptyObject');
-var invariant = require('fbjs/lib/invariant');
-var ReactFeatureFlags = require('ReactFeatureFlags');
+import {REACT_COROUTINE_TYPE, REACT_YIELD_TYPE} from 'ReactCoroutine';
+import {REACT_PORTAL_TYPE} from 'ReactPortal';
+import {
+  createWorkInProgress,
+  createFiberFromElement,
+  createFiberFromFragment,
+  createFiberFromText,
+  createFiberFromCoroutine,
+  createFiberFromYield,
+  createFiberFromPortal,
+} from 'ReactFiber';
+import {NoEffect, Placement, Deletion} from 'ReactTypeOfSideEffect';
+import {
+  FunctionalComponent,
+  ClassComponent,
+  HostText,
+  HostPortal,
+  CoroutineComponent,
+  YieldComponent,
+  Fragment,
+} from 'ReactTypeOfWork';
+import emptyObject from 'fbjs/lib/emptyObject';
+import invariant from 'fbjs/lib/invariant';
+import ReactFeatureFlags from 'ReactFeatureFlags';
+import {getCurrentFiberStackAddendum} from 'ReactDebugCurrentFiber';
+import warning from 'fbjs/lib/warning';
 
 if (__DEV__) {
-  var {getCurrentFiberStackAddendum} = require('ReactDebugCurrentFiber');
-  var warning = require('fbjs/lib/warning');
   var didWarnAboutMaps = false;
   /**
    * Warn if there's no key explicitly set on dynamic arrays of children or
@@ -74,30 +87,8 @@ if (__DEV__) {
   };
 }
 
-const {
-  createWorkInProgress,
-  createFiberFromElement,
-  createFiberFromFragment,
-  createFiberFromText,
-  createFiberFromCoroutine,
-  createFiberFromYield,
-  createFiberFromPortal,
-} = ReactFiber;
-
 const isArray = Array.isArray;
 
-const {
-  FunctionalComponent,
-  ClassComponent,
-  HostText,
-  HostPortal,
-  CoroutineComponent,
-  YieldComponent,
-  Fragment,
-} = ReactTypeOfWork;
-
-const {NoEffect, Placement, Deletion} = ReactTypeOfSideEffect;
-
 const ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
 const FAUX_ITERATOR_SYMBOL = '@@iterator'; // Before Symbol spec.
 // The Symbol used to tag the ReactElement type. If there is no native Symbol
@@ -123,20 +114,15 @@ function coerceRef(current: Fiber | null, element: ReactElement) {
   let mixedRef = element.ref;
   if (mixedRef !== null && typeof mixedRef !== 'function') {
     if (element._owner) {
-      const owner: ?(Fiber | ReactInstance) = (element._owner: any);
+      const owner: ?Fiber = (element._owner: any);
       let inst;
       if (owner) {
-        if (typeof owner.tag === 'number') {
-          const ownerFiber = ((owner: any): Fiber);
-          invariant(
-            ownerFiber.tag === ClassComponent,
-            'Stateless function components cannot have refs.',
-          );
-          inst = ownerFiber.stateNode;
-        } else {
-          // Stack
-          inst = (owner: any).getPublicInstance();
-        }
+        const ownerFiber = ((owner: any): Fiber);
+        invariant(
+          ownerFiber.tag === ClassComponent,
+          'Stateless function components cannot have refs.',
+        );
+        inst = ownerFiber.stateNode;
       }
       invariant(
         inst,
@@ -1491,13 +1477,13 @@ function ChildReconciler(shouldClone, shouldTrackSideEffects) {
   return reconcileChildFibers;
 }
 
-exports.reconcileChildFibers = ChildReconciler(true, true);
+export const reconcileChildFibers = ChildReconciler(true, true);
 
-exports.reconcileChildFibersInPlace = ChildReconciler(false, true);
+export const reconcileChildFibersInPlace = ChildReconciler(false, true);
 
-exports.mountChildFibersInPlace = ChildReconciler(false, false);
+export const mountChildFibersInPlace = ChildReconciler(false, false);
 
-exports.cloneChildFibers = function(
+export function cloneChildFibers(
   current: Fiber | null,
   workInProgress: Fiber,
 ): void {
@@ -1530,4 +1516,4 @@ exports.cloneChildFibers = function(
     newChild.return = workInProgress;
   }
   newChild.sibling = null;
-};
+}
diff --git a/src/renderers/shared/fiber/ReactDebugCurrentFiber.js b/src/renderers/shared/fiber/ReactDebugCurrentFiber.js
index dd36659201f..41118a13d7d 100644
--- a/src/renderers/shared/fiber/ReactDebugCurrentFiber.js
+++ b/src/renderers/shared/fiber/ReactDebugCurrentFiber.js
@@ -14,18 +14,17 @@
 
 import type {Fiber} from 'ReactFiber';
 
-type LifeCyclePhase = 'render' | 'getChildContext';
+import getComponentName from 'getComponentName';
+import {ReactDebugCurrentFrame} from 'ReactGlobalSharedState';
+import {
+  getStackAddendumByWorkInProgressFiber,
+} from 'ReactFiberComponentTreeHook';
 
-var {ReactDebugCurrentFrame} = require('ReactGlobalSharedState');
+const {setCurrentStackImplementation} = ReactDebugCurrentFrame;
 
-if (__DEV__) {
-  var getComponentName = require('getComponentName');
-  var {
-    getStackAddendumByWorkInProgressFiber,
-  } = require('ReactFiberComponentTreeHook');
-}
+type LifeCyclePhase = 'render' | 'getChildContext';
 
-function getCurrentFiberOwnerName(): string | null {
+export function getCurrentFiberOwnerName(): string | null {
   if (__DEV__) {
     const fiber = ReactDebugCurrentFiber.current;
     if (fiber === null) {
@@ -38,7 +37,7 @@ function getCurrentFiberOwnerName(): string | null {
   return null;
 }
 
-function getCurrentFiberStackAddendum(): string | null {
+export function getCurrentFiberStackAddendum(): string | null {
   if (__DEV__) {
     const fiber = ReactDebugCurrentFiber.current;
     if (fiber === null) {
@@ -51,25 +50,24 @@ function getCurrentFiberStackAddendum(): string | null {
   return null;
 }
 
-function resetCurrentFiber() {
-  ReactDebugCurrentFrame.getCurrentStack = null;
+export function resetCurrentFiber() {
+  setCurrentStackImplementation(null);
   ReactDebugCurrentFiber.current = null;
   ReactDebugCurrentFiber.phase = null;
 }
 
-function setCurrentFiber(fiber: Fiber | null, phase: LifeCyclePhase | null) {
-  ReactDebugCurrentFrame.getCurrentStack = getCurrentFiberStackAddendum;
+export function setCurrentFiber(
+  fiber: Fiber | null,
+  phase: LifeCyclePhase | null,
+) {
+  setCurrentStackImplementation(getCurrentFiberStackAddendum);
   ReactDebugCurrentFiber.current = fiber;
   ReactDebugCurrentFiber.phase = phase;
 }
 
-var ReactDebugCurrentFiber = {
+const ReactDebugCurrentFiber = {
   current: (null: Fiber | null),
   phase: (null: LifeCyclePhase | null),
-  resetCurrentFiber,
-  setCurrentFiber,
-  getCurrentFiberOwnerName,
-  getCurrentFiberStackAddendum,
 };
 
-module.exports = ReactDebugCurrentFiber;
+export default ReactDebugCurrentFiber;
diff --git a/src/renderers/shared/fiber/ReactDebugFiberPerf.js b/src/renderers/shared/fiber/ReactDebugFiberPerf.js
index b0ed45fb5dc..2bbf21961e7 100644
--- a/src/renderers/shared/fiber/ReactDebugFiberPerf.js
+++ b/src/renderers/shared/fiber/ReactDebugFiberPerf.js
@@ -12,6 +12,17 @@
 
 import type {Fiber} from 'ReactFiber';
 
+import {
+  HostRoot,
+  HostComponent,
+  HostText,
+  HostPortal,
+  YieldComponent,
+  Fragment,
+} from 'ReactTypeOfWork';
+import getComponentName from 'getComponentName';
+import emptyFunction from 'fbjs/lib/emptyFunction';
+
 type MeasurementPhase =
   | 'componentWillMount'
   | 'componentWillUnmount'
@@ -22,21 +33,24 @@ type MeasurementPhase =
   | 'componentDidMount'
   | 'getChildContext';
 
-// Trust the developer to only use this with a __DEV__ check
-let ReactDebugFiberPerf = ((null: any): typeof ReactDebugFiberPerf);
+export let recordEffect = emptyFunction;
+export let recordScheduleUpdate = emptyFunction;
+export let startWorkTimer = emptyFunction;
+export let cancelWorkTimer = emptyFunction;
+export let stopWorkTimer = emptyFunction;
+export let stopFailedWorkTimer = emptyFunction;
+export let startPhaseTimer = emptyFunction;
+export let stopPhaseTimer = emptyFunction;
+export let startWorkLoopTimer = emptyFunction;
+export let stopWorkLoopTimer = emptyFunction;
+export let startCommitTimer = emptyFunction;
+export let stopCommitTimer = emptyFunction;
+export let startCommitHostEffectsTimer = emptyFunction;
+export let stopCommitHostEffectsTimer = emptyFunction;
+export let startCommitLifeCyclesTimer = emptyFunction;
+export let stopCommitLifeCyclesTimer = emptyFunction;
 
 if (__DEV__) {
-  const {
-    HostRoot,
-    HostComponent,
-    HostText,
-    HostPortal,
-    YieldComponent,
-    Fragment,
-  } = require('ReactTypeOfWork');
-
-  const getComponentName = require('getComponentName');
-
   // Prefix measurements so that it's possible to filter them.
   // Longer prefixes are hard to read in DevTools.
   const reactEmoji = '\u269B';
@@ -217,199 +231,195 @@ if (__DEV__) {
     }
   };
 
-  ReactDebugFiberPerf = {
-    recordEffect(): void {
-      effectCountInCurrentCommit++;
-    },
+  recordEffect = function(): void {
+    effectCountInCurrentCommit++;
+  };
 
-    recordScheduleUpdate(): void {
-      if (isCommitting) {
-        hasScheduledUpdateInCurrentCommit = true;
-      }
-      if (
-        currentPhase !== null &&
-        currentPhase !== 'componentWillMount' &&
-        currentPhase !== 'componentWillReceiveProps'
-      ) {
-        hasScheduledUpdateInCurrentPhase = true;
-      }
-    },
+  recordScheduleUpdate = function(): void {
+    if (isCommitting) {
+      hasScheduledUpdateInCurrentCommit = true;
+    }
+    if (
+      currentPhase !== null &&
+      currentPhase !== 'componentWillMount' &&
+      currentPhase !== 'componentWillReceiveProps'
+    ) {
+      hasScheduledUpdateInCurrentPhase = true;
+    }
+  };
 
-    startWorkTimer(fiber: Fiber): void {
-      if (!supportsUserTiming || shouldIgnoreFiber(fiber)) {
-        return;
-      }
-      // If we pause, this is the fiber to unwind from.
-      currentFiber = fiber;
-      if (!beginFiberMark(fiber, null)) {
-        return;
-      }
-      fiber._debugIsCurrentlyTiming = true;
-    },
+  startWorkTimer = function(fiber: Fiber): void {
+    if (!supportsUserTiming || shouldIgnoreFiber(fiber)) {
+      return;
+    }
+    // If we pause, this is the fiber to unwind from.
+    currentFiber = fiber;
+    if (!beginFiberMark(fiber, null)) {
+      return;
+    }
+    fiber._debugIsCurrentlyTiming = true;
+  };
 
-    cancelWorkTimer(fiber: Fiber): void {
-      if (!supportsUserTiming || shouldIgnoreFiber(fiber)) {
-        return;
-      }
-      // Remember we shouldn't complete measurement for this fiber.
-      // Otherwise flamechart will be deep even for small updates.
-      fiber._debugIsCurrentlyTiming = false;
-      clearFiberMark(fiber, null);
-    },
-
-    stopWorkTimer(fiber: Fiber): void {
-      if (!supportsUserTiming || shouldIgnoreFiber(fiber)) {
-        return;
-      }
-      // If we pause, its parent is the fiber to unwind from.
-      currentFiber = fiber.return;
-      if (!fiber._debugIsCurrentlyTiming) {
-        return;
-      }
-      fiber._debugIsCurrentlyTiming = false;
-      endFiberMark(fiber, null, null);
-    },
+  cancelWorkTimer = function(fiber: Fiber): void {
+    if (!supportsUserTiming || shouldIgnoreFiber(fiber)) {
+      return;
+    }
+    // Remember we shouldn't complete measurement for this fiber.
+    // Otherwise flamechart will be deep even for small updates.
+    fiber._debugIsCurrentlyTiming = false;
+    clearFiberMark(fiber, null);
+  };
 
-    stopFailedWorkTimer(fiber: Fiber): void {
-      if (!supportsUserTiming || shouldIgnoreFiber(fiber)) {
-        return;
-      }
-      // If we pause, its parent is the fiber to unwind from.
-      currentFiber = fiber.return;
-      if (!fiber._debugIsCurrentlyTiming) {
-        return;
-      }
-      fiber._debugIsCurrentlyTiming = false;
-      const warning = 'An error was thrown inside this error boundary';
-      endFiberMark(fiber, null, warning);
-    },
-
-    startPhaseTimer(fiber: Fiber, phase: MeasurementPhase): void {
-      if (!supportsUserTiming) {
-        return;
-      }
-      clearPendingPhaseMeasurement();
-      if (!beginFiberMark(fiber, phase)) {
-        return;
-      }
-      currentPhaseFiber = fiber;
-      currentPhase = phase;
-    },
+  stopWorkTimer = function(fiber: Fiber): void {
+    if (!supportsUserTiming || shouldIgnoreFiber(fiber)) {
+      return;
+    }
+    // If we pause, its parent is the fiber to unwind from.
+    currentFiber = fiber.return;
+    if (!fiber._debugIsCurrentlyTiming) {
+      return;
+    }
+    fiber._debugIsCurrentlyTiming = false;
+    endFiberMark(fiber, null, null);
+  };
 
-    stopPhaseTimer(): void {
-      if (!supportsUserTiming) {
-        return;
-      }
-      if (currentPhase !== null && currentPhaseFiber !== null) {
-        const warning = hasScheduledUpdateInCurrentPhase
-          ? 'Scheduled a cascading update'
-          : null;
-        endFiberMark(currentPhaseFiber, currentPhase, warning);
-      }
-      currentPhase = null;
-      currentPhaseFiber = null;
-    },
+  stopFailedWorkTimer = function(fiber: Fiber): void {
+    if (!supportsUserTiming || shouldIgnoreFiber(fiber)) {
+      return;
+    }
+    // If we pause, its parent is the fiber to unwind from.
+    currentFiber = fiber.return;
+    if (!fiber._debugIsCurrentlyTiming) {
+      return;
+    }
+    fiber._debugIsCurrentlyTiming = false;
+    const warning = 'An error was thrown inside this error boundary';
+    endFiberMark(fiber, null, warning);
+  };
 
-    startWorkLoopTimer(): void {
-      if (!supportsUserTiming) {
-        return;
-      }
-      commitCountInCurrentWorkLoop = 0;
-      // This is top level call.
-      // Any other measurements are performed within.
-      beginMark('(React Tree Reconciliation)');
-      // Resume any measurements that were in progress during the last loop.
-      resumeTimers();
-    },
-
-    stopWorkLoopTimer(): void {
-      if (!supportsUserTiming) {
-        return;
-      }
-      const warning = commitCountInCurrentWorkLoop > 1
-        ? 'There were cascading updates'
+  startPhaseTimer = function(fiber: Fiber, phase: MeasurementPhase): void {
+    if (!supportsUserTiming) {
+      return;
+    }
+    clearPendingPhaseMeasurement();
+    if (!beginFiberMark(fiber, phase)) {
+      return;
+    }
+    currentPhaseFiber = fiber;
+    currentPhase = phase;
+  };
+
+  stopPhaseTimer = function(): void {
+    if (!supportsUserTiming) {
+      return;
+    }
+    if (currentPhase !== null && currentPhaseFiber !== null) {
+      const warning = hasScheduledUpdateInCurrentPhase
+        ? 'Scheduled a cascading update'
         : null;
-      commitCountInCurrentWorkLoop = 0;
-      // Pause any measurements until the next loop.
-      pauseTimers();
-      endMark(
-        '(React Tree Reconciliation)',
-        '(React Tree Reconciliation)',
-        warning,
-      );
-    },
-
-    startCommitTimer(): void {
-      if (!supportsUserTiming) {
-        return;
-      }
-      isCommitting = true;
-      hasScheduledUpdateInCurrentCommit = false;
-      labelsInCurrentCommit.clear();
-      beginMark('(Committing Changes)');
-    },
-
-    stopCommitTimer(): void {
-      if (!supportsUserTiming) {
-        return;
-      }
+      endFiberMark(currentPhaseFiber, currentPhase, warning);
+    }
+    currentPhase = null;
+    currentPhaseFiber = null;
+  };
 
-      let warning = null;
-      if (hasScheduledUpdateInCurrentCommit) {
-        warning = 'Lifecycle hook scheduled a cascading update';
-      } else if (commitCountInCurrentWorkLoop > 0) {
-        warning = 'Caused by a cascading update in earlier commit';
-      }
-      hasScheduledUpdateInCurrentCommit = false;
-      commitCountInCurrentWorkLoop++;
-      isCommitting = false;
-      labelsInCurrentCommit.clear();
+  startWorkLoopTimer = function(): void {
+    if (!supportsUserTiming) {
+      return;
+    }
+    commitCountInCurrentWorkLoop = 0;
+    // This is top level call.
+    // Any other measurements are performed within.
+    beginMark('(React Tree Reconciliation)');
+    // Resume any measurements that were in progress during the last loop.
+    resumeTimers();
+  };
 
-      endMark('(Committing Changes)', '(Committing Changes)', warning);
-    },
+  stopWorkLoopTimer = function(): void {
+    if (!supportsUserTiming) {
+      return;
+    }
+    const warning = commitCountInCurrentWorkLoop > 1
+      ? 'There were cascading updates'
+      : null;
+    commitCountInCurrentWorkLoop = 0;
+    // Pause any measurements until the next loop.
+    pauseTimers();
+    endMark(
+      '(React Tree Reconciliation)',
+      '(React Tree Reconciliation)',
+      warning,
+    );
+  };
 
-    startCommitHostEffectsTimer(): void {
-      if (!supportsUserTiming) {
-        return;
-      }
-      effectCountInCurrentCommit = 0;
-      beginMark('(Committing Host Effects)');
-    },
+  startCommitTimer = function(): void {
+    if (!supportsUserTiming) {
+      return;
+    }
+    isCommitting = true;
+    hasScheduledUpdateInCurrentCommit = false;
+    labelsInCurrentCommit.clear();
+    beginMark('(Committing Changes)');
+  };
 
-    stopCommitHostEffectsTimer(): void {
-      if (!supportsUserTiming) {
-        return;
-      }
-      const count = effectCountInCurrentCommit;
-      effectCountInCurrentCommit = 0;
-      endMark(
-        `(Committing Host Effects: ${count} Total)`,
-        '(Committing Host Effects)',
-        null,
-      );
-    },
-
-    startCommitLifeCyclesTimer(): void {
-      if (!supportsUserTiming) {
-        return;
-      }
-      effectCountInCurrentCommit = 0;
-      beginMark('(Calling Lifecycle Methods)');
-    },
+  stopCommitTimer = function(): void {
+    if (!supportsUserTiming) {
+      return;
+    }
 
-    stopCommitLifeCyclesTimer(): void {
-      if (!supportsUserTiming) {
-        return;
-      }
-      const count = effectCountInCurrentCommit;
-      effectCountInCurrentCommit = 0;
-      endMark(
-        `(Calling Lifecycle Methods: ${count} Total)`,
-        '(Calling Lifecycle Methods)',
-        null,
-      );
-    },
+    let warning = null;
+    if (hasScheduledUpdateInCurrentCommit) {
+      warning = 'Lifecycle hook scheduled a cascading update';
+    } else if (commitCountInCurrentWorkLoop > 0) {
+      warning = 'Caused by a cascading update in earlier commit';
+    }
+    hasScheduledUpdateInCurrentCommit = false;
+    commitCountInCurrentWorkLoop++;
+    isCommitting = false;
+    labelsInCurrentCommit.clear();
+
+    endMark('(Committing Changes)', '(Committing Changes)', warning);
+  };
+
+  startCommitHostEffectsTimer = function(): void {
+    if (!supportsUserTiming) {
+      return;
+    }
+    effectCountInCurrentCommit = 0;
+    beginMark('(Committing Host Effects)');
   };
-}
 
-module.exports = ReactDebugFiberPerf;
+  stopCommitHostEffectsTimer = function(): void {
+    if (!supportsUserTiming) {
+      return;
+    }
+    const count = effectCountInCurrentCommit;
+    effectCountInCurrentCommit = 0;
+    endMark(
+      `(Committing Host Effects: ${count} Total)`,
+      '(Committing Host Effects)',
+      null,
+    );
+  };
+
+  startCommitLifeCyclesTimer = function(): void {
+    if (!supportsUserTiming) {
+      return;
+    }
+    effectCountInCurrentCommit = 0;
+    beginMark('(Calling Lifecycle Methods)');
+  };
+
+  stopCommitLifeCyclesTimer = function(): void {
+    if (!supportsUserTiming) {
+      return;
+    }
+    const count = effectCountInCurrentCommit;
+    effectCountInCurrentCommit = 0;
+    endMark(
+      `(Calling Lifecycle Methods: ${count} Total)`,
+      '(Calling Lifecycle Methods)',
+      null,
+    );
+  };
+}
diff --git a/src/renderers/shared/fiber/ReactFiber.js b/src/renderers/shared/fiber/ReactFiber.js
index 2a07cf2dc63..0dc883db811 100644
--- a/src/renderers/shared/fiber/ReactFiber.js
+++ b/src/renderers/shared/fiber/ReactFiber.js
@@ -13,7 +13,6 @@
 'use strict';
 
 import type {ReactElement, Source} from 'ReactElementType';
-import type {ReactInstance, DebugID} from 'ReactInstanceType';
 import type {
   ReactCoroutine,
   ReactFragment,
@@ -26,7 +25,8 @@ import type {TypeOfSideEffect} from 'ReactTypeOfSideEffect';
 import type {PriorityLevel} from 'ReactPriorityLevel';
 import type {UpdateQueue} from 'ReactFiberUpdateQueue';
 
-var {
+import getComponentName from 'getComponentName';
+import {
   IndeterminateComponent,
   ClassComponent,
   HostRoot,
@@ -36,18 +36,14 @@ var {
   CoroutineComponent,
   YieldComponent,
   Fragment,
-} = require('ReactTypeOfWork');
+} from 'ReactTypeOfWork';
 
-var {NoWork} = require('ReactPriorityLevel');
-
-var {NoContext} = require('ReactTypeOfInternalContext');
-
-var {NoEffect} = require('ReactTypeOfSideEffect');
-
-var invariant = require('fbjs/lib/invariant');
+import {NoWork} from 'ReactPriorityLevel';
+import {NoContext} from 'ReactTypeOfInternalContext';
+import {NoEffect} from 'ReactTypeOfSideEffect';
+import invariant from 'fbjs/lib/invariant';
 
 if (__DEV__) {
-  var getComponentName = require('getComponentName');
   var hasBadMapPolyfill = false;
   try {
     const nonExtensibleObject = Object.preventExtensions({});
@@ -149,9 +145,9 @@ export type Fiber = {|
   // workInProgress : Fiber ->  alternate The alternate used for reuse happens
   // to be the same as work in progress.
   // __DEV__ only
-  _debugID?: DebugID,
+  _debugID?: number,
   _debugSource?: Source | null,
-  _debugOwner?: Fiber | ReactInstance | null, // Stack compatible
+  _debugOwner?: Fiber | null, // Stack compatible
   _debugIsCurrentlyTiming?: boolean,
 |};
 
@@ -234,7 +230,7 @@ function shouldConstruct(Component) {
 }
 
 // This is used to create an alternate fiber to do work on.
-exports.createWorkInProgress = function(
+export function createWorkInProgress(
   current: Fiber,
   renderPriority: PriorityLevel,
 ): Fiber {
@@ -289,14 +285,14 @@ exports.createWorkInProgress = function(
   workInProgress.ref = current.ref;
 
   return workInProgress;
-};
+}
 
-exports.createHostRootFiber = function(): Fiber {
+export function createHostRootFiber(): Fiber {
   const fiber = createFiber(HostRoot, null, NoContext);
   return fiber;
-};
+}
 
-exports.createFiberFromElement = function(
+export function createFiberFromElement(
   element: ReactElement,
   internalContextTag: TypeOfInternalContext,
   priorityLevel: PriorityLevel,
@@ -321,9 +317,9 @@ exports.createFiberFromElement = function(
   }
 
   return fiber;
-};
+}
 
-exports.createFiberFromFragment = function(
+export function createFiberFromFragment(
   elements: ReactFragment,
   internalContextTag: TypeOfInternalContext,
   priorityLevel: PriorityLevel,
@@ -334,9 +330,9 @@ exports.createFiberFromFragment = function(
   fiber.pendingProps = elements;
   fiber.pendingWorkPriority = priorityLevel;
   return fiber;
-};
+}
 
-exports.createFiberFromText = function(
+export function createFiberFromText(
   content: string,
   internalContextTag: TypeOfInternalContext,
   priorityLevel: PriorityLevel,
@@ -345,13 +341,13 @@ exports.createFiberFromText = function(
   fiber.pendingProps = content;
   fiber.pendingWorkPriority = priorityLevel;
   return fiber;
-};
+}
 
-function createFiberFromElementType(
+export function createFiberFromElementType(
   type: mixed,
   key: null | string,
   internalContextTag: TypeOfInternalContext,
-  debugOwner: null | Fiber | ReactInstance,
+  debugOwner: null | Fiber,
 ): Fiber {
   let fiber;
   if (typeof type === 'function') {
@@ -403,15 +399,13 @@ function createFiberFromElementType(
   return fiber;
 }
 
-exports.createFiberFromElementType = createFiberFromElementType;
-
-exports.createFiberFromHostInstanceForDeletion = function(): Fiber {
+export function createFiberFromHostInstanceForDeletion(): Fiber {
   const fiber = createFiber(HostComponent, null, NoContext);
   fiber.type = 'DELETED';
   return fiber;
-};
+}
 
-exports.createFiberFromCoroutine = function(
+export function createFiberFromCoroutine(
   coroutine: ReactCoroutine,
   internalContextTag: TypeOfInternalContext,
   priorityLevel: PriorityLevel,
@@ -425,18 +419,18 @@ exports.createFiberFromCoroutine = function(
   fiber.pendingProps = coroutine;
   fiber.pendingWorkPriority = priorityLevel;
   return fiber;
-};
+}
 
-exports.createFiberFromYield = function(
+export function createFiberFromYield(
   yieldNode: ReactYield,
   internalContextTag: TypeOfInternalContext,
   priorityLevel: PriorityLevel,
 ): Fiber {
   const fiber = createFiber(YieldComponent, null, internalContextTag);
   return fiber;
-};
+}
 
-exports.createFiberFromPortal = function(
+export function createFiberFromPortal(
   portal: ReactPortal,
   internalContextTag: TypeOfInternalContext,
   priorityLevel: PriorityLevel,
@@ -449,11 +443,11 @@ exports.createFiberFromPortal = function(
     implementation: portal.implementation,
   };
   return fiber;
-};
+}
 
-exports.largerPriority = function(
+export function largerPriority(
   p1: PriorityLevel,
   p2: PriorityLevel,
 ): PriorityLevel {
   return p1 !== NoWork && (p2 === NoWork || p2 > p1) ? p1 : p2;
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberBeginWork.js b/src/renderers/shared/fiber/ReactFiberBeginWork.js
index d9821063f47..0edc832b2ed 100644
--- a/src/renderers/shared/fiber/ReactFiberBeginWork.js
+++ b/src/renderers/shared/fiber/ReactFiberBeginWork.js
@@ -20,23 +20,14 @@ import type {FiberRoot} from 'ReactFiberRoot';
 import type {HostConfig} from 'ReactFiberReconciler';
 import type {PriorityLevel} from 'ReactPriorityLevel';
 
-var {
+import {
   mountChildFibersInPlace,
   reconcileChildFibers,
   reconcileChildFibersInPlace,
   cloneChildFibers,
-} = require('ReactChildFiber');
-var {beginUpdateQueue} = require('ReactFiberUpdateQueue');
-var ReactTypeOfWork = require('ReactTypeOfWork');
-var {
-  getMaskedContext,
-  getUnmaskedContext,
-  hasContextChanged,
-  pushContextProvider,
-  pushTopLevelContextObject,
-  invalidateContextProvider,
-} = require('ReactFiberContext');
-var {
+} from 'ReactChildFiber';
+import {beginUpdateQueue} from 'ReactFiberUpdateQueue';
+import {
   IndeterminateComponent,
   FunctionalComponent,
   ClassComponent,
@@ -48,28 +39,39 @@ var {
   CoroutineHandlerPhase,
   YieldComponent,
   Fragment,
-} = ReactTypeOfWork;
-var {NoWork, OffscreenPriority} = require('ReactPriorityLevel');
-var {
+} from 'ReactTypeOfWork';
+import {
+  getMaskedContext,
+  getUnmaskedContext,
+  hasContextChanged,
+  pushContextProvider,
+  pushTopLevelContextObject,
+  invalidateContextProvider,
+} from 'ReactFiberContext';
+import {NoWork, OffscreenPriority} from 'ReactPriorityLevel';
+import {
   PerformedWork,
   Placement,
   ContentReset,
   Err,
   Ref,
-} = require('ReactTypeOfSideEffect');
-var ReactFiberClassComponent = require('ReactFiberClassComponent');
-var {ReactCurrentOwner} = require('ReactGlobalSharedState');
-var invariant = require('fbjs/lib/invariant');
+} from 'ReactTypeOfSideEffect';
+import ReactFiberClassComponent from 'ReactFiberClassComponent';
+import {ReactCurrentOwner} from 'ReactGlobalSharedState';
+import invariant from 'fbjs/lib/invariant';
+import {
+  setCurrentFiber,
+  getCurrentFiberOwnerName,
+  getCurrentFiberStackAddendum,
+} from 'ReactDebugCurrentFiber';
+import {cancelWorkTimer} from 'ReactDebugFiberPerf';
+import warning from 'fbjs/lib/warning';
 
 if (__DEV__) {
-  var ReactDebugCurrentFiber = require('ReactDebugCurrentFiber');
-  var {cancelWorkTimer} = require('ReactDebugFiberPerf');
-  var warning = require('fbjs/lib/warning');
-
   var warnedAboutStatelessRefs = {};
 }
 
-module.exports = function<T, P, I, TI, PI, C, CX, PL>(
+export default function<T, P, I, TI, PI, C, CX, PL>(
   config: HostConfig<T, P, I, TI, PI, C, CX, PL>,
   hostContext: HostContext<C, CX>,
   hydrationContext: HydrationContext<C>,
@@ -209,9 +211,9 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
 
     if (__DEV__) {
       ReactCurrentOwner.current = workInProgress;
-      ReactDebugCurrentFiber.setCurrentFiber(workInProgress, 'render');
+      setCurrentFiber(workInProgress, 'render');
       nextChildren = fn(nextProps, context);
-      ReactDebugCurrentFiber.setCurrentFiber(workInProgress, null);
+      setCurrentFiber(workInProgress, null);
     } else {
       nextChildren = fn(nextProps, context);
     }
@@ -283,9 +285,9 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
     ReactCurrentOwner.current = workInProgress;
     let nextChildren;
     if (__DEV__) {
-      ReactDebugCurrentFiber.setCurrentFiber(workInProgress, 'render');
+      setCurrentFiber(workInProgress, 'render');
       nextChildren = instance.render();
-      ReactDebugCurrentFiber.setCurrentFiber(workInProgress, null);
+      setCurrentFiber(workInProgress, null);
     } else {
       nextChildren = instance.render();
     }
@@ -504,7 +506,7 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
         }
         if (workInProgress.ref !== null) {
           let info = '';
-          const ownerName = ReactDebugCurrentFiber.getCurrentFiberOwnerName();
+          const ownerName = getCurrentFiberOwnerName();
           if (ownerName) {
             info += '\n\nCheck the render method of `' + ownerName + '`.';
           }
@@ -521,7 +523,7 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
               'Stateless function components cannot be given refs. ' +
                 'Attempts to access this ref will fail.%s%s',
               info,
-              ReactDebugCurrentFiber.getCurrentFiberStackAddendum(),
+              getCurrentFiberStackAddendum(),
             );
           }
         }
@@ -723,7 +725,7 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
     }
 
     if (__DEV__) {
-      ReactDebugCurrentFiber.setCurrentFiber(workInProgress, null);
+      setCurrentFiber(workInProgress, null);
     }
 
     switch (workInProgress.tag) {
@@ -836,4 +838,4 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
     beginWork,
     beginFailedWork,
   };
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberClassComponent.js b/src/renderers/shared/fiber/ReactFiberClassComponent.js
index e726cfd5692..8710750301c 100644
--- a/src/renderers/shared/fiber/ReactFiberClassComponent.js
+++ b/src/renderers/shared/fiber/ReactFiberClassComponent.js
@@ -15,37 +15,35 @@
 import type {Fiber} from 'ReactFiber';
 import type {PriorityLevel} from 'ReactPriorityLevel';
 
-var {Update} = require('ReactTypeOfSideEffect');
-
-var ReactFeatureFlags = require('ReactFeatureFlags');
-var {AsyncUpdates} = require('ReactTypeOfInternalContext');
-
-var {
+import {Update} from 'ReactTypeOfSideEffect';
+import ReactFeatureFlags from 'ReactFeatureFlags';
+import {AsyncUpdates} from 'ReactTypeOfInternalContext';
+import {
   cacheContext,
   getMaskedContext,
   getUnmaskedContext,
+  hasContextChanged,
   isContextConsumer,
-} = require('ReactFiberContext');
-var {
+} from 'ReactFiberContext';
+import {
   addUpdate,
   addReplaceUpdate,
   addForceUpdate,
   beginUpdateQueue,
-} = require('ReactFiberUpdateQueue');
-var {hasContextChanged} = require('ReactFiberContext');
-var {isMounted} = require('ReactFiberTreeReflection');
-var ReactInstanceMap = require('ReactInstanceMap');
-var emptyObject = require('fbjs/lib/emptyObject');
-var getComponentName = require('getComponentName');
-var shallowEqual = require('fbjs/lib/shallowEqual');
-var invariant = require('fbjs/lib/invariant');
+} from 'ReactFiberUpdateQueue';
+import {isMounted} from 'ReactFiberTreeReflection';
+import {startPhaseTimer, stopPhaseTimer} from 'ReactDebugFiberPerf';
+import ReactInstanceMap from 'ReactInstanceMap';
+import emptyObject from 'fbjs/lib/emptyObject';
+import getComponentName from 'getComponentName';
+import shallowEqual from 'fbjs/lib/shallowEqual';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
 
 const fakeInternalInstance = {};
 const isArray = Array.isArray;
 
 if (__DEV__) {
-  var {startPhaseTimer, stopPhaseTimer} = require('ReactDebugFiberPerf');
-  var warning = require('fbjs/lib/warning');
   var warnOnInvalidCallback = function(callback: mixed, callerName: string) {
     warning(
       callback === null || typeof callback === 'function',
@@ -78,7 +76,7 @@ if (__DEV__) {
   Object.freeze(fakeInternalInstance);
 }
 
-module.exports = function(
+export default function(
   scheduleUpdate: (fiber: Fiber, priorityLevel: PriorityLevel) => void,
   getPriorityContext: (fiber: Fiber, forceAsync: boolean) => PriorityLevel,
   memoizeProps: (workInProgress: Fiber, props: any) => void,
@@ -681,4 +679,4 @@ module.exports = function(
     // resumeMountClassInstance,
     updateClassInstance,
   };
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberCommitWork.js b/src/renderers/shared/fiber/ReactFiberCommitWork.js
index e90da861065..bf7bda3a8cb 100644
--- a/src/renderers/shared/fiber/ReactFiberCommitWork.js
+++ b/src/renderers/shared/fiber/ReactFiberCommitWork.js
@@ -15,37 +15,28 @@
 import type {Fiber} from 'ReactFiber';
 import type {HostConfig} from 'ReactFiberReconciler';
 
-var ReactTypeOfWork = require('ReactTypeOfWork');
-var {
+import {
   ClassComponent,
   HostRoot,
   HostComponent,
   HostText,
   HostPortal,
   CoroutineComponent,
-} = ReactTypeOfWork;
-var {commitCallbacks} = require('ReactFiberUpdateQueue');
-var {onCommitUnmount} = require('ReactFiberDevToolsHook');
-var {
+} from 'ReactTypeOfWork';
+import {commitCallbacks} from 'ReactFiberUpdateQueue';
+import {onCommitUnmount} from 'ReactFiberDevToolsHook';
+import ReactErrorUtils from 'ReactErrorUtils';
+import {Placement, Update, Callback, ContentReset} from 'ReactTypeOfSideEffect';
+import invariant from 'fbjs/lib/invariant';
+import {startPhaseTimer, stopPhaseTimer} from 'ReactDebugFiberPerf';
+
+const {
   invokeGuardedCallback,
   hasCaughtError,
   clearCaughtError,
-} = require('ReactErrorUtils');
-
-var {
-  Placement,
-  Update,
-  Callback,
-  ContentReset,
-} = require('ReactTypeOfSideEffect');
-
-var invariant = require('fbjs/lib/invariant');
+} = ReactErrorUtils;
 
-if (__DEV__) {
-  var {startPhaseTimer, stopPhaseTimer} = require('ReactDebugFiberPerf');
-}
-
-module.exports = function<T, P, I, TI, PI, C, CX, PL>(
+export default function<T, P, I, TI, PI, C, CX, PL>(
   config: HostConfig<T, P, I, TI, PI, C, CX, PL>,
   captureError: (failedFiber: Fiber, error: mixed) => Fiber | null,
 ) {
@@ -597,4 +588,4 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
     commitAttachRef,
     commitDetachRef,
   };
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberCompleteWork.js b/src/renderers/shared/fiber/ReactFiberCompleteWork.js
index c733f036933..5aa38e739b5 100644
--- a/src/renderers/shared/fiber/ReactFiberCompleteWork.js
+++ b/src/renderers/shared/fiber/ReactFiberCompleteWork.js
@@ -20,12 +20,9 @@ import type {HydrationContext} from 'ReactFiberHydrationContext';
 import type {FiberRoot} from 'ReactFiberRoot';
 import type {HostConfig} from 'ReactFiberReconciler';
 
-var {reconcileChildFibers} = require('ReactChildFiber');
-var {popContextProvider} = require('ReactFiberContext');
-var ReactTypeOfWork = require('ReactTypeOfWork');
-var ReactTypeOfSideEffect = require('ReactTypeOfSideEffect');
-var ReactPriorityLevel = require('ReactPriorityLevel');
-var {
+import {reconcileChildFibers} from 'ReactChildFiber';
+import {popContextProvider} from 'ReactFiberContext';
+import {
   IndeterminateComponent,
   FunctionalComponent,
   ClassComponent,
@@ -37,17 +34,13 @@ var {
   CoroutineHandlerPhase,
   YieldComponent,
   Fragment,
-} = ReactTypeOfWork;
-var {Placement, Ref, Update} = ReactTypeOfSideEffect;
-var {OffscreenPriority} = ReactPriorityLevel;
+} from 'ReactTypeOfWork';
+import {Placement, Ref, Update} from 'ReactTypeOfSideEffect';
+import {OffscreenPriority} from 'ReactPriorityLevel';
+import {setCurrentFiber} from 'ReactDebugCurrentFiber';
+import invariant from 'fbjs/lib/invariant';
 
-if (__DEV__) {
-  var ReactDebugCurrentFiber = require('ReactDebugCurrentFiber');
-}
-
-var invariant = require('fbjs/lib/invariant');
-
-module.exports = function<T, P, I, TI, PI, C, CX, PL>(
+export default function<T, P, I, TI, PI, C, CX, PL>(
   config: HostConfig<T, P, I, TI, PI, C, CX, PL>,
   hostContext: HostContext<C, CX>,
   hydrationContext: HydrationContext<C>,
@@ -187,7 +180,7 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
     renderPriority: PriorityLevel,
   ): Fiber | null {
     if (__DEV__) {
-      ReactDebugCurrentFiber.setCurrentFiber(workInProgress, null);
+      setCurrentFiber(workInProgress, null);
     }
 
     // Get the latest props.
@@ -399,4 +392,4 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
   return {
     completeWork,
   };
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberContext.js b/src/renderers/shared/fiber/ReactFiberContext.js
index 3b9b7ed9d43..67f97695fa9 100644
--- a/src/renderers/shared/fiber/ReactFiberContext.js
+++ b/src/renderers/shared/fiber/ReactFiberContext.js
@@ -15,18 +15,22 @@
 import type {Fiber} from 'ReactFiber';
 import type {StackCursor} from 'ReactFiberStack';
 
-var emptyObject = require('fbjs/lib/emptyObject');
-var getComponentName = require('getComponentName');
-var invariant = require('fbjs/lib/invariant');
-var {isFiberMounted} = require('ReactFiberTreeReflection');
-var {ClassComponent, HostRoot} = require('ReactTypeOfWork');
-const {createCursor, pop, push} = require('ReactFiberStack');
+import emptyObject from 'fbjs/lib/emptyObject';
+import getComponentName from 'getComponentName';
+import invariant from 'fbjs/lib/invariant';
+import {isFiberMounted} from 'ReactFiberTreeReflection';
+import {ClassComponent, HostRoot} from 'ReactTypeOfWork';
+import {createCursor, pop, push} from 'ReactFiberStack';
+import warning from 'fbjs/lib/warning';
+import checkPropTypes from 'prop-types/checkPropTypes';
+import {
+  getCurrentFiberStackAddendum,
+  setCurrentFiber,
+  resetCurrentFiber,
+} from 'ReactDebugCurrentFiber';
+import {startPhaseTimer, stopPhaseTimer} from 'ReactDebugFiberPerf';
 
 if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var checkPropTypes = require('prop-types/checkPropTypes');
-  var ReactDebugCurrentFiber = require('ReactDebugCurrentFiber');
-  var {startPhaseTimer, stopPhaseTimer} = require('ReactDebugFiberPerf');
   var warnedAboutMissingGetChildContext = {};
 }
 
@@ -39,7 +43,7 @@ let didPerformWorkStackCursor: StackCursor<boolean> = createCursor(false);
 // pushed the next context provider, and now need to merge their contexts.
 let previousContext: Object = emptyObject;
 
-function getUnmaskedContext(workInProgress: Fiber): Object {
+export function getUnmaskedContext(workInProgress: Fiber): Object {
   const hasOwnContext = isContextProvider(workInProgress);
   if (hasOwnContext) {
     // If the fiber is a context provider itself, when we read its context
@@ -50,9 +54,8 @@ function getUnmaskedContext(workInProgress: Fiber): Object {
   }
   return contextStackCursor.current;
 }
-exports.getUnmaskedContext = getUnmaskedContext;
 
-function cacheContext(
+export function cacheContext(
   workInProgress: Fiber,
   unmaskedContext: Object,
   maskedContext: Object,
@@ -61,9 +64,8 @@ function cacheContext(
   instance.__reactInternalMemoizedUnmaskedChildContext = unmaskedContext;
   instance.__reactInternalMemoizedMaskedChildContext = maskedContext;
 }
-exports.cacheContext = cacheContext;
 
-exports.getMaskedContext = function(
+export function getMaskedContext(
   workInProgress: Fiber,
   unmaskedContext: Object,
 ) {
@@ -91,15 +93,15 @@ exports.getMaskedContext = function(
 
   if (__DEV__) {
     const name = getComponentName(workInProgress) || 'Unknown';
-    ReactDebugCurrentFiber.setCurrentFiber(workInProgress, null);
+    setCurrentFiber(workInProgress, null);
     checkPropTypes(
       contextTypes,
       context,
       'context',
       name,
-      ReactDebugCurrentFiber.getCurrentFiberStackAddendum,
+      getCurrentFiberStackAddendum,
     );
-    ReactDebugCurrentFiber.resetCurrentFiber();
+    resetCurrentFiber();
   }
 
   // Cache unmasked context so we can avoid recreating masked context unless necessary.
@@ -109,23 +111,21 @@ exports.getMaskedContext = function(
   }
 
   return context;
-};
+}
 
-exports.hasContextChanged = function(): boolean {
+export function hasContextChanged(): boolean {
   return didPerformWorkStackCursor.current;
-};
+}
 
-function isContextConsumer(fiber: Fiber): boolean {
+export function isContextConsumer(fiber: Fiber): boolean {
   return fiber.tag === ClassComponent && fiber.type.contextTypes != null;
 }
-exports.isContextConsumer = isContextConsumer;
 
-function isContextProvider(fiber: Fiber): boolean {
+export function isContextProvider(fiber: Fiber): boolean {
   return fiber.tag === ClassComponent && fiber.type.childContextTypes != null;
 }
-exports.isContextProvider = isContextProvider;
 
-function popContextProvider(fiber: Fiber): void {
+export function popContextProvider(fiber: Fiber): void {
   if (!isContextProvider(fiber)) {
     return;
   }
@@ -133,9 +133,8 @@ function popContextProvider(fiber: Fiber): void {
   pop(didPerformWorkStackCursor, fiber);
   pop(contextStackCursor, fiber);
 }
-exports.popContextProvider = popContextProvider;
 
-exports.pushTopLevelContextObject = function(
+export function pushTopLevelContextObject(
   fiber: Fiber,
   context: Object,
   didChange: boolean,
@@ -148,9 +147,9 @@ exports.pushTopLevelContextObject = function(
 
   push(contextStackCursor, context, fiber);
   push(didPerformWorkStackCursor, didChange, fiber);
-};
+}
 
-function processChildContext(
+export function processChildContext(
   fiber: Fiber,
   parentContext: Object,
   isReconciling: boolean,
@@ -181,11 +180,11 @@ function processChildContext(
 
   let childContext;
   if (__DEV__) {
-    ReactDebugCurrentFiber.setCurrentFiber(fiber, 'getChildContext');
+    setCurrentFiber(fiber, 'getChildContext');
     startPhaseTimer(fiber, 'getChildContext');
     childContext = instance.getChildContext();
     stopPhaseTimer();
-    ReactDebugCurrentFiber.resetCurrentFiber();
+    resetCurrentFiber();
   } else {
     childContext = instance.getChildContext();
   }
@@ -205,22 +204,21 @@ function processChildContext(
     // assume anything about the given fiber. We won't pass it down if we aren't sure.
     // TODO: remove this hack when we delete unstable_renderSubtree in Fiber.
     const workInProgress = isReconciling ? fiber : null;
-    ReactDebugCurrentFiber.setCurrentFiber(workInProgress, null);
+    setCurrentFiber(workInProgress, null);
     checkPropTypes(
       childContextTypes,
       childContext,
       'child context',
       name,
-      ReactDebugCurrentFiber.getCurrentFiberStackAddendum,
+      getCurrentFiberStackAddendum,
     );
-    ReactDebugCurrentFiber.resetCurrentFiber();
+    resetCurrentFiber();
   }
 
   return {...parentContext, ...childContext};
 }
-exports.processChildContext = processChildContext;
 
-exports.pushContextProvider = function(workInProgress: Fiber): boolean {
+export function pushContextProvider(workInProgress: Fiber): boolean {
   if (!isContextProvider(workInProgress)) {
     return false;
   }
@@ -244,9 +242,9 @@ exports.pushContextProvider = function(workInProgress: Fiber): boolean {
   );
 
   return true;
-};
+}
 
-exports.invalidateContextProvider = function(
+export function invalidateContextProvider(
   workInProgress: Fiber,
   didChange: boolean,
 ): void {
@@ -279,15 +277,15 @@ exports.invalidateContextProvider = function(
     pop(didPerformWorkStackCursor, workInProgress);
     push(didPerformWorkStackCursor, didChange, workInProgress);
   }
-};
+}
 
-exports.resetContext = function(): void {
+export function resetContext(): void {
   previousContext = emptyObject;
   contextStackCursor.current = emptyObject;
   didPerformWorkStackCursor.current = false;
-};
+}
 
-exports.findCurrentUnmaskedContext = function(fiber: Fiber): Object {
+export function findCurrentUnmaskedContext(fiber: Fiber): Object {
   // Currently this is only used with renderSubtreeIntoContainer; not sure if it
   // makes sense elsewhere
   invariant(
@@ -310,4 +308,4 @@ exports.findCurrentUnmaskedContext = function(fiber: Fiber): Object {
     node = parent;
   }
   return node.stateNode.context;
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberDevToolsHook.js b/src/renderers/shared/fiber/ReactFiberDevToolsHook.js
index 86d090c6b5c..d010b216039 100644
--- a/src/renderers/shared/fiber/ReactFiberDevToolsHook.js
+++ b/src/renderers/shared/fiber/ReactFiberDevToolsHook.js
@@ -17,9 +17,7 @@ import type {FiberRoot} from 'ReactFiberRoot';
 
 declare var __REACT_DEVTOOLS_GLOBAL_HOOK__: Object | void;
 
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import warning from 'fbjs/lib/warning';
 
 let onCommitFiberRoot = null;
 let onCommitFiberUnmount = null;
@@ -38,7 +36,7 @@ function catchErrors(fn) {
   };
 }
 
-function injectInternals(internals: Object): boolean {
+export function injectInternals(internals: Object): boolean {
   if (typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ === 'undefined') {
     // No DevTools
     return false;
@@ -75,18 +73,14 @@ function injectInternals(internals: Object): boolean {
   return true;
 }
 
-function onCommitRoot(root: FiberRoot) {
+export function onCommitRoot(root: FiberRoot) {
   if (typeof onCommitFiberRoot === 'function') {
     onCommitFiberRoot(root);
   }
 }
 
-function onCommitUnmount(fiber: Fiber) {
+export function onCommitUnmount(fiber: Fiber) {
   if (typeof onCommitFiberUnmount === 'function') {
     onCommitFiberUnmount(fiber);
   }
 }
-
-exports.injectInternals = injectInternals;
-exports.onCommitRoot = onCommitRoot;
-exports.onCommitUnmount = onCommitUnmount;
diff --git a/src/renderers/shared/fiber/ReactFiberErrorLogger.js b/src/renderers/shared/fiber/ReactFiberErrorLogger.js
index 74ec53e946a..df66755a801 100644
--- a/src/renderers/shared/fiber/ReactFiberErrorLogger.js
+++ b/src/renderers/shared/fiber/ReactFiberErrorLogger.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-const invariant = require('fbjs/lib/invariant');
+import invariant from 'fbjs/lib/invariant';
 
 import type {CapturedError} from 'ReactFiberScheduler';
 
@@ -20,7 +20,7 @@ const defaultShowDialog = (capturedError: CapturedError) => true;
 
 let showDialog = defaultShowDialog;
 
-function logCapturedError(capturedError: CapturedError): void {
+export function logCapturedError(capturedError: CapturedError): void {
   const logError = showDialog(capturedError);
 
   // Allow injected showDialog() to prevent default console.error logging.
@@ -77,11 +77,11 @@ function logCapturedError(capturedError: CapturedError): void {
   }
 }
 
-exports.injection = {
-  /**
-   * Display custom dialog for lifecycle errors.
-   * Return false to prevent default behavior of logging to console.error.
-   */
+/**
+ * Display custom dialog for lifecycle errors.
+ * Return false to prevent default behavior of logging to console.error.
+ */
+export const injection = {
   injectDialog(fn: (e: CapturedError) => boolean) {
     invariant(
       showDialog === defaultShowDialog,
@@ -94,5 +94,3 @@ exports.injection = {
     showDialog = fn;
   },
 };
-
-exports.logCapturedError = logCapturedError;
diff --git a/src/renderers/shared/fiber/ReactFiberHostContext.js b/src/renderers/shared/fiber/ReactFiberHostContext.js
index 448bd8c72ea..86eac102047 100644
--- a/src/renderers/shared/fiber/ReactFiberHostContext.js
+++ b/src/renderers/shared/fiber/ReactFiberHostContext.js
@@ -16,9 +16,8 @@ import type {Fiber} from 'ReactFiber';
 import type {HostConfig} from 'ReactFiberReconciler';
 import type {StackCursor} from 'ReactFiberStack';
 
-const {createCursor, pop, push} = require('ReactFiberStack');
-
-const invariant = require('fbjs/lib/invariant');
+import {createCursor, pop, push} from 'ReactFiberStack';
+import invariant from 'fbjs/lib/invariant';
 
 declare class NoContextT {}
 const NO_CONTEXT: NoContextT = ({}: any);
@@ -33,7 +32,7 @@ export type HostContext<C, CX> = {
   resetHostContainer(): void,
 };
 
-module.exports = function<T, P, I, TI, PI, C, CX, PL>(
+export default function<T, P, I, TI, PI, C, CX, PL>(
   config: HostConfig<T, P, I, TI, PI, C, CX, PL>,
 ): HostContext<C, CX> {
   const {getChildHostContext, getRootHostContext} = config;
@@ -127,4 +126,4 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
     pushHostContext,
     resetHostContainer,
   };
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberHydrationContext.js b/src/renderers/shared/fiber/ReactFiberHydrationContext.js
index e39202b2aea..a1215b12dad 100644
--- a/src/renderers/shared/fiber/ReactFiberHydrationContext.js
+++ b/src/renderers/shared/fiber/ReactFiberHydrationContext.js
@@ -15,12 +15,10 @@
 import type {Fiber} from 'ReactFiber';
 import type {HostConfig} from 'ReactFiberReconciler';
 
-var invariant = require('fbjs/lib/invariant');
-
-const {HostComponent, HostText, HostRoot} = require('ReactTypeOfWork');
-const {Deletion, Placement} = require('ReactTypeOfSideEffect');
-
-const {createFiberFromHostInstanceForDeletion} = require('ReactFiber');
+import invariant from 'fbjs/lib/invariant';
+import {HostComponent, HostText, HostRoot} from 'ReactTypeOfWork';
+import {Deletion, Placement} from 'ReactTypeOfSideEffect';
+import {createFiberFromHostInstanceForDeletion} from 'ReactFiber';
 
 export type HydrationContext<C> = {
   enterHydrationState(fiber: Fiber): boolean,
@@ -31,7 +29,7 @@ export type HydrationContext<C> = {
   popHydrationState(fiber: Fiber): boolean,
 };
 
-module.exports = function<T, P, I, TI, PI, C, CX, PL>(
+export default function<T, P, I, TI, PI, C, CX, PL>(
   config: HostConfig<T, P, I, TI, PI, C, CX, PL>,
 ): HydrationContext<C> {
   const {
@@ -315,4 +313,4 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
     prepareToHydrateHostTextInstance,
     popHydrationState,
   };
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberInstrumentation.js b/src/renderers/shared/fiber/ReactFiberInstrumentation.js
index bb2abc533b7..24f0d4fbfd6 100644
--- a/src/renderers/shared/fiber/ReactFiberInstrumentation.js
+++ b/src/renderers/shared/fiber/ReactFiberInstrumentation.js
@@ -20,4 +20,4 @@ var ReactFiberInstrumentation = {
   debugTool: null,
 };
 
-module.exports = ReactFiberInstrumentation;
+export default ReactFiberInstrumentation;
diff --git a/src/renderers/shared/fiber/ReactFiberReconciler.js b/src/renderers/shared/fiber/ReactFiberReconciler.js
index 2edad984993..347922f36ca 100644
--- a/src/renderers/shared/fiber/ReactFiberReconciler.js
+++ b/src/renderers/shared/fiber/ReactFiberReconciler.js
@@ -17,32 +17,27 @@ import type {FiberRoot} from 'ReactFiberRoot';
 import type {PriorityLevel} from 'ReactPriorityLevel';
 import type {ReactNodeList} from 'ReactTypes';
 
-var ReactFeatureFlags = require('ReactFeatureFlags');
+import getComponentName from 'getComponentName';
+import ReactFeatureFlags from 'ReactFeatureFlags';
+import {addTopLevelUpdate} from 'ReactFiberUpdateQueue';
 
-var {addTopLevelUpdate} = require('ReactFiberUpdateQueue');
-
-var {
+import {
   findCurrentUnmaskedContext,
   isContextProvider,
   processChildContext,
-} = require('ReactFiberContext');
-var {createFiberRoot} = require('ReactFiberRoot');
-var ReactFiberScheduler = require('ReactFiberScheduler');
-var {HostComponent} = require('ReactTypeOfWork');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var ReactFiberInstrumentation = require('ReactFiberInstrumentation');
-  var ReactDebugCurrentFiber = require('ReactDebugCurrentFiber');
-  var getComponentName = require('getComponentName');
-}
-
-var {
+} from 'ReactFiberContext';
+import {createFiberRoot} from 'ReactFiberRoot';
+import ReactFiberScheduler from 'ReactFiberScheduler';
+import ReactInstanceMap from 'ReactInstanceMap';
+import {HostComponent} from 'ReactTypeOfWork';
+import emptyObject from 'fbjs/lib/emptyObject';
+import warning from 'fbjs/lib/warning';
+import ReactFiberInstrumentation from 'ReactFiberInstrumentation';
+import ReactDebugCurrentFiber from 'ReactDebugCurrentFiber';
+import {
   findCurrentHostFiber,
   findCurrentHostFiberWithNoPortals,
-} = require('ReactFiberTreeReflection');
-
-var getContextForSubtree = require('getContextForSubtree');
+} from 'ReactFiberTreeReflection';
 
 export type Deadline = {
   timeRemaining: () => number,
@@ -181,14 +176,21 @@ export type Reconciler<C, I, TI> = {
   findHostInstanceWithNoPortals(component: Fiber): I | TI | null,
 };
 
-getContextForSubtree._injectFiber(function(fiber: Fiber) {
+function getContextForSubtree(
+  parentComponent: ?ReactComponent<any, any, any>,
+): Object {
+  if (!parentComponent) {
+    return emptyObject;
+  }
+
+  const fiber = ReactInstanceMap.get(parentComponent);
   const parentContext = findCurrentUnmaskedContext(fiber);
   return isContextProvider(fiber)
     ? processChildContext(fiber, parentContext, false)
     : parentContext;
-});
+}
 
-module.exports = function<T, P, I, TI, PI, C, CX, PL>(
+export default function<T, P, I, TI, PI, C, CX, PL>(
   config: HostConfig<T, P, I, TI, PI, C, CX, PL>,
 ): Reconciler<C, I, TI> {
   var {getPublicInstance} = config;
@@ -325,4 +327,4 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
       return hostFiber.stateNode;
     },
   };
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberRoot.js b/src/renderers/shared/fiber/ReactFiberRoot.js
index 409b7065544..d8c16863ccd 100644
--- a/src/renderers/shared/fiber/ReactFiberRoot.js
+++ b/src/renderers/shared/fiber/ReactFiberRoot.js
@@ -14,7 +14,7 @@
 
 import type {Fiber} from 'ReactFiber';
 
-const {createHostRootFiber} = require('ReactFiber');
+import {createHostRootFiber} from 'ReactFiber';
 
 export type FiberRoot = {
   // Any additional information from the host associated with this root.
@@ -30,7 +30,7 @@ export type FiberRoot = {
   pendingContext: Object | null,
 };
 
-exports.createFiberRoot = function(containerInfo: any): FiberRoot {
+export function createFiberRoot(containerInfo: any): FiberRoot {
   // Cyclic construction. This cheats the type system right now because
   // stateNode is any.
   const uninitializedFiber = createHostRootFiber();
@@ -44,4 +44,4 @@ exports.createFiberRoot = function(containerInfo: any): FiberRoot {
   };
   uninitializedFiber.stateNode = root;
   return root;
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberScheduler.js b/src/renderers/shared/fiber/ReactFiberScheduler.js
index be8545fcace..09f396af277 100644
--- a/src/renderers/shared/fiber/ReactFiberScheduler.js
+++ b/src/renderers/shared/fiber/ReactFiberScheduler.js
@@ -32,41 +32,32 @@ export type HandleErrorInfo = {
   componentStack: string,
 };
 
-var {popContextProvider} = require('ReactFiberContext');
-const {reset} = require('ReactFiberStack');
-var {
+import {popContextProvider} from 'ReactFiberContext';
+import {reset} from 'ReactFiberStack';
+import {
   getStackAddendumByWorkInProgressFiber,
-} = require('ReactFiberComponentTreeHook');
-var {logCapturedError} = require('ReactFiberErrorLogger');
-var {
-  invokeGuardedCallback,
-  hasCaughtError,
-  clearCaughtError,
-} = require('ReactErrorUtils');
-
-var ReactFiberBeginWork = require('ReactFiberBeginWork');
-var ReactFiberCompleteWork = require('ReactFiberCompleteWork');
-var ReactFiberCommitWork = require('ReactFiberCommitWork');
-var ReactFiberHostContext = require('ReactFiberHostContext');
-var ReactFiberHydrationContext = require('ReactFiberHydrationContext');
-var {ReactCurrentOwner} = require('ReactGlobalSharedState');
-var getComponentName = require('getComponentName');
-
-var {createWorkInProgress, largerPriority} = require('ReactFiber');
-var {onCommitRoot} = require('ReactFiberDevToolsHook');
-
-var {
+} from 'ReactFiberComponentTreeHook';
+import {logCapturedError} from 'ReactFiberErrorLogger';
+import ReactErrorUtils from 'ReactErrorUtils';
+import ReactFiberBeginWork from 'ReactFiberBeginWork';
+import ReactFiberCompleteWork from 'ReactFiberCompleteWork';
+import ReactFiberCommitWork from 'ReactFiberCommitWork';
+import ReactFiberHostContext from 'ReactFiberHostContext';
+import ReactFiberHydrationContext from 'ReactFiberHydrationContext';
+import {ReactCurrentOwner} from 'ReactGlobalSharedState';
+import getComponentName from 'getComponentName';
+import {createWorkInProgress, largerPriority} from 'ReactFiber';
+import {onCommitRoot} from 'ReactFiberDevToolsHook';
+import {
   NoWork,
   SynchronousPriority,
   TaskPriority,
   HighPriority,
   LowPriority,
   OffscreenPriority,
-} = require('ReactPriorityLevel');
-
-var {AsyncUpdates} = require('ReactTypeOfInternalContext');
-
-var {
+} from 'ReactPriorityLevel';
+import {AsyncUpdates} from 'ReactTypeOfInternalContext';
+import {
   PerformedWork,
   Placement,
   Update,
@@ -76,41 +67,45 @@ var {
   Callback,
   Err,
   Ref,
-} = require('ReactTypeOfSideEffect');
-
-var {
+} from 'ReactTypeOfSideEffect';
+import {
   HostRoot,
   HostComponent,
   HostPortal,
   ClassComponent,
-} = require('ReactTypeOfWork');
-
-var {getUpdatePriority} = require('ReactFiberUpdateQueue');
-
-var {resetContext} = require('ReactFiberContext');
-
-var invariant = require('fbjs/lib/invariant');
+} from 'ReactTypeOfWork';
+import {getUpdatePriority} from 'ReactFiberUpdateQueue';
+import {resetContext} from 'ReactFiberContext';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
+import ReactFiberInstrumentation from 'ReactFiberInstrumentation';
+import ReactDebugCurrentFiber, {
+  setCurrentFiber,
+  resetCurrentFiber,
+} from 'ReactDebugCurrentFiber';
+import {
+  recordEffect,
+  recordScheduleUpdate,
+  startWorkTimer,
+  stopWorkTimer,
+  stopFailedWorkTimer,
+  startWorkLoopTimer,
+  stopWorkLoopTimer,
+  startCommitTimer,
+  stopCommitTimer,
+  startCommitHostEffectsTimer,
+  stopCommitHostEffectsTimer,
+  startCommitLifeCyclesTimer,
+  stopCommitLifeCyclesTimer,
+} from 'ReactDebugFiberPerf';
+
+const {
+  invokeGuardedCallback,
+  hasCaughtError,
+  clearCaughtError,
+} = ReactErrorUtils;
 
 if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var ReactFiberInstrumentation = require('ReactFiberInstrumentation');
-  var ReactDebugCurrentFiber = require('ReactDebugCurrentFiber');
-  var {
-    recordEffect,
-    recordScheduleUpdate,
-    startWorkTimer,
-    stopWorkTimer,
-    stopFailedWorkTimer,
-    startWorkLoopTimer,
-    stopWorkLoopTimer,
-    startCommitTimer,
-    stopCommitTimer,
-    startCommitHostEffectsTimer,
-    stopCommitHostEffectsTimer,
-    startCommitLifeCyclesTimer,
-    stopCommitLifeCyclesTimer,
-  } = require('ReactDebugFiberPerf');
-
   var warnAboutUpdateOnUnmounted = function(instance: ReactClass<any>) {
     const ctor = instance.constructor;
     warning(
@@ -146,7 +141,7 @@ if (__DEV__) {
 
 var timeHeuristicForUnitOfWork = 1;
 
-module.exports = function<T, P, I, TI, PI, C, CX, PL>(
+export default function<T, P, I, TI, PI, C, CX, PL>(
   config: HostConfig<T, P, I, TI, PI, C, CX, PL>,
 ) {
   const hostContext = ReactFiberHostContext(config);
@@ -310,7 +305,7 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
   function commitAllHostEffects() {
     while (nextEffect !== null) {
       if (__DEV__) {
-        ReactDebugCurrentFiber.setCurrentFiber(nextEffect, null);
+        setCurrentFiber(nextEffect, null);
         recordEffect();
       }
 
@@ -371,7 +366,7 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
     }
 
     if (__DEV__) {
-      ReactDebugCurrentFiber.resetCurrentFiber();
+      resetCurrentFiber();
     }
   }
 
@@ -712,7 +707,7 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
 
     ReactCurrentOwner.current = null;
     if (__DEV__) {
-      ReactDebugCurrentFiber.resetCurrentFiber();
+      resetCurrentFiber();
     }
 
     return next;
@@ -741,7 +736,7 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
 
     ReactCurrentOwner.current = null;
     if (__DEV__) {
-      ReactDebugCurrentFiber.resetCurrentFiber();
+      resetCurrentFiber();
     }
 
     return next;
@@ -1094,7 +1089,7 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
     // It is no longer valid because we exited the user code.
     ReactCurrentOwner.current = null;
     if (__DEV__) {
-      ReactDebugCurrentFiber.resetCurrentFiber();
+      resetCurrentFiber();
     }
 
     // Search for the nearest error boundary.
@@ -1569,4 +1564,4 @@ module.exports = function<T, P, I, TI, PI, C, CX, PL>(
     flushSync: flushSync,
     deferredUpdates: deferredUpdates,
   };
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberStack.js b/src/renderers/shared/fiber/ReactFiberStack.js
index a933ef4057d..a6a901a47f5 100644
--- a/src/renderers/shared/fiber/ReactFiberStack.js
+++ b/src/renderers/shared/fiber/ReactFiberStack.js
@@ -13,14 +13,11 @@
 'use strict';
 
 import type {Fiber} from 'ReactFiber';
-
 export type StackCursor<T> = {
   current: T,
 };
 
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import warning from 'fbjs/lib/warning';
 
 const valueStack: Array<any> = [];
 
@@ -30,17 +27,17 @@ if (__DEV__) {
 
 let index = -1;
 
-exports.createCursor = function<T>(defaultValue: T): StackCursor<T> {
+export function createCursor<T>(defaultValue: T): StackCursor<T> {
   return {
     current: defaultValue,
   };
-};
+}
 
-exports.isEmpty = function(): boolean {
+export function isEmpty(): boolean {
   return index === -1;
-};
+}
 
-exports.pop = function<T>(cursor: StackCursor<T>, fiber: Fiber): void {
+export function pop<T>(cursor: StackCursor<T>, fiber: Fiber): void {
   if (index < 0) {
     if (__DEV__) {
       warning(false, 'Unexpected pop.');
@@ -63,13 +60,9 @@ exports.pop = function<T>(cursor: StackCursor<T>, fiber: Fiber): void {
   }
 
   index--;
-};
+}
 
-exports.push = function<T>(
-  cursor: StackCursor<T>,
-  value: T,
-  fiber: Fiber,
-): void {
+export function push<T>(cursor: StackCursor<T>, value: T, fiber: Fiber): void {
   index++;
 
   valueStack[index] = cursor.current;
@@ -79,9 +72,9 @@ exports.push = function<T>(
   }
 
   cursor.current = value;
-};
+}
 
-exports.reset = function(): void {
+export function reset(): void {
   while (index > -1) {
     valueStack[index] = null;
 
@@ -91,4 +84,4 @@ exports.reset = function(): void {
 
     index--;
   }
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberTreeReflection.js b/src/renderers/shared/fiber/ReactFiberTreeReflection.js
index 33ddf1bf1b0..6ed8df3eb69 100644
--- a/src/renderers/shared/fiber/ReactFiberTreeReflection.js
+++ b/src/renderers/shared/fiber/ReactFiberTreeReflection.js
@@ -14,25 +14,19 @@
 
 import type {Fiber} from 'ReactFiber';
 
-var ReactInstanceMap = require('ReactInstanceMap');
-var {ReactCurrentOwner} = require('ReactGlobalSharedState');
-
-var getComponentName = require('getComponentName');
-var invariant = require('fbjs/lib/invariant');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
-var {
+import ReactInstanceMap from 'ReactInstanceMap';
+import {ReactCurrentOwner} from 'ReactGlobalSharedState';
+import getComponentName from 'getComponentName';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
+import {
   ClassComponent,
   HostComponent,
   HostRoot,
   HostPortal,
   HostText,
-} = require('ReactTypeOfWork');
-
-var {NoEffect, Placement} = require('ReactTypeOfSideEffect');
+} from 'ReactTypeOfWork';
+import {NoEffect, Placement} from 'ReactTypeOfSideEffect';
 
 var MOUNTING = 1;
 var MOUNTED = 2;
@@ -66,13 +60,12 @@ function isFiberMountedImpl(fiber: Fiber): number {
   // that has been unmounted.
   return UNMOUNTED;
 }
-exports.isFiberMounted = function(fiber: Fiber): boolean {
+
+export function isFiberMounted(fiber: Fiber): boolean {
   return isFiberMountedImpl(fiber) === MOUNTED;
-};
+}
 
-exports.isMounted = function(
-  component: ReactComponent<any, any, any>,
-): boolean {
+export function isMounted(component: ReactComponent<any, any, any>): boolean {
   if (__DEV__) {
     const owner = (ReactCurrentOwner.current: any);
     if (owner !== null && owner.tag === ClassComponent) {
@@ -96,7 +89,7 @@ exports.isMounted = function(
     return false;
   }
   return isFiberMountedImpl(fiber) === MOUNTED;
-};
+}
 
 function assertIsMounted(fiber) {
   invariant(
@@ -105,7 +98,7 @@ function assertIsMounted(fiber) {
   );
 }
 
-function findCurrentFiberUsingSlowPath(fiber: Fiber): Fiber | null {
+export function findCurrentFiberUsingSlowPath(fiber: Fiber): Fiber | null {
   let alternate = fiber.alternate;
   if (!alternate) {
     // If there is no alternate, then we only need to check if it is mounted.
@@ -230,9 +223,8 @@ function findCurrentFiberUsingSlowPath(fiber: Fiber): Fiber | null {
   // Otherwise B has to be current branch.
   return alternate;
 }
-exports.findCurrentFiberUsingSlowPath = findCurrentFiberUsingSlowPath;
 
-exports.findCurrentHostFiber = function(parent: Fiber): Fiber | null {
+export function findCurrentHostFiber(parent: Fiber): Fiber | null {
   const currentParent = findCurrentFiberUsingSlowPath(parent);
   if (!currentParent) {
     return null;
@@ -263,11 +255,9 @@ exports.findCurrentHostFiber = function(parent: Fiber): Fiber | null {
   // Flow needs the return null here, but ESLint complains about it.
   // eslint-disable-next-line no-unreachable
   return null;
-};
+}
 
-exports.findCurrentHostFiberWithNoPortals = function(
-  parent: Fiber,
-): Fiber | null {
+export function findCurrentHostFiberWithNoPortals(parent: Fiber): Fiber | null {
   const currentParent = findCurrentFiberUsingSlowPath(parent);
   if (!currentParent) {
     return null;
@@ -298,4 +288,4 @@ exports.findCurrentHostFiberWithNoPortals = function(
   // Flow needs the return null here, but ESLint complains about it.
   // eslint-disable-next-line no-unreachable
   return null;
-};
+}
diff --git a/src/renderers/shared/fiber/ReactFiberUpdateQueue.js b/src/renderers/shared/fiber/ReactFiberUpdateQueue.js
index e58ce420f37..ff00c4895f8 100644
--- a/src/renderers/shared/fiber/ReactFiberUpdateQueue.js
+++ b/src/renderers/shared/fiber/ReactFiberUpdateQueue.js
@@ -15,20 +15,11 @@
 import type {Fiber} from 'ReactFiber';
 import type {PriorityLevel} from 'ReactPriorityLevel';
 
-const {Callback: CallbackEffect} = require('ReactTypeOfSideEffect');
-
-const {
-  NoWork,
-  SynchronousPriority,
-  TaskPriority,
-} = require('ReactPriorityLevel');
-
-const {ClassComponent, HostRoot} = require('ReactTypeOfWork');
-
-const invariant = require('fbjs/lib/invariant');
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import {Callback as CallbackEffect} from 'ReactTypeOfSideEffect';
+import {NoWork, SynchronousPriority, TaskPriority} from 'ReactPriorityLevel';
+import {ClassComponent, HostRoot} from 'ReactTypeOfWork';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
 
 type PartialState<State, Props> =
   | $Subtype<State>
@@ -280,7 +271,7 @@ function insertUpdate(fiber: Fiber, update: Update): Update | null {
   }
 }
 
-function addUpdate(
+export function addUpdate(
   fiber: Fiber,
   partialState: PartialState<any, any> | null,
   callback: mixed,
@@ -297,9 +288,8 @@ function addUpdate(
   };
   insertUpdate(fiber, update);
 }
-exports.addUpdate = addUpdate;
 
-function addReplaceUpdate(
+export function addReplaceUpdate(
   fiber: Fiber,
   state: any | null,
   callback: Callback | null,
@@ -316,9 +306,8 @@ function addReplaceUpdate(
   };
   insertUpdate(fiber, update);
 }
-exports.addReplaceUpdate = addReplaceUpdate;
 
-function addForceUpdate(
+export function addForceUpdate(
   fiber: Fiber,
   callback: Callback | null,
   priorityLevel: PriorityLevel,
@@ -334,9 +323,8 @@ function addForceUpdate(
   };
   insertUpdate(fiber, update);
 }
-exports.addForceUpdate = addForceUpdate;
 
-function getUpdatePriority(fiber: Fiber): PriorityLevel {
+export function getUpdatePriority(fiber: Fiber): PriorityLevel {
   const updateQueue = fiber.updateQueue;
   if (updateQueue === null) {
     return NoWork;
@@ -346,9 +334,8 @@ function getUpdatePriority(fiber: Fiber): PriorityLevel {
   }
   return updateQueue.first !== null ? updateQueue.first.priorityLevel : NoWork;
 }
-exports.getUpdatePriority = getUpdatePriority;
 
-function addTopLevelUpdate(
+export function addTopLevelUpdate(
   fiber: Fiber,
   partialState: PartialState<any, any>,
   callback: Callback | null,
@@ -384,7 +371,6 @@ function addTopLevelUpdate(
     }
   }
 }
-exports.addTopLevelUpdate = addTopLevelUpdate;
 
 function getStateFromUpdate(update, instance, prevState, props) {
   const partialState = update.partialState;
@@ -396,7 +382,7 @@ function getStateFromUpdate(update, instance, prevState, props) {
   }
 }
 
-function beginUpdateQueue(
+export function beginUpdateQueue(
   current: Fiber | null,
   workInProgress: Fiber,
   queue: UpdateQueue,
@@ -491,9 +477,8 @@ function beginUpdateQueue(
 
   return state;
 }
-exports.beginUpdateQueue = beginUpdateQueue;
 
-function commitCallbacks(
+export function commitCallbacks(
   finishedWork: Fiber,
   queue: UpdateQueue,
   context: mixed,
@@ -517,4 +502,3 @@ function commitCallbacks(
     callback.call(context);
   }
 }
-exports.commitCallbacks = commitCallbacks;
diff --git a/src/renderers/shared/fiber/ReactPriorityLevel.js b/src/renderers/shared/fiber/ReactPriorityLevel.js
index eed8ce10e66..5377a439e9a 100644
--- a/src/renderers/shared/fiber/ReactPriorityLevel.js
+++ b/src/renderers/shared/fiber/ReactPriorityLevel.js
@@ -14,11 +14,9 @@
 
 export type PriorityLevel = 0 | 1 | 2 | 3 | 4 | 5;
 
-module.exports = {
-  NoWork: 0, // No work is pending.
-  SynchronousPriority: 1, // For controlled text inputs. Synchronous side-effects.
-  TaskPriority: 2, // Completes at the end of the current tick.
-  HighPriority: 3, // Interaction that needs to complete pretty soon to feel responsive.
-  LowPriority: 4, // Data fetching, or result from updating stores.
-  OffscreenPriority: 5, // Won't be visible but do the work in case it becomes visible.
-};
+export const NoWork = 0; // No work is pending.
+export const SynchronousPriority = 1; // For controlled text inputs. Synchronous side-effects.
+export const TaskPriority = 2; // Completes at the end of the current tick.
+export const HighPriority = 3; // Interaction that needs to complete pretty soon to feel responsive.
+export const LowPriority = 4; // Data fetching, or result from updating stores.
+export const OffscreenPriority = 5; // Won't be visible but do the work in case it becomes visible.
diff --git a/src/renderers/shared/fiber/ReactTypeOfInternalContext.js b/src/renderers/shared/fiber/ReactTypeOfInternalContext.js
index 89a3d2938d7..d83d05b4d52 100644
--- a/src/renderers/shared/fiber/ReactTypeOfInternalContext.js
+++ b/src/renderers/shared/fiber/ReactTypeOfInternalContext.js
@@ -14,7 +14,5 @@
 
 export type TypeOfInternalContext = number;
 
-module.exports = {
-  NoContext: 0,
-  AsyncUpdates: 1,
-};
+export const NoContext = 0;
+export const AsyncUpdates = 1;
diff --git a/src/renderers/shared/fiber/ReactTypeOfSideEffect.js b/src/renderers/shared/fiber/ReactTypeOfSideEffect.js
index b98f71cc4a2..8ca6285f5ee 100644
--- a/src/renderers/shared/fiber/ReactTypeOfSideEffect.js
+++ b/src/renderers/shared/fiber/ReactTypeOfSideEffect.js
@@ -14,17 +14,15 @@
 
 export type TypeOfSideEffect = number;
 
-module.exports = {
-  // Don't change these two values:
-  NoEffect: 0, //           0b00000000
-  PerformedWork: 1, //      0b00000001
-  // You can change the rest (and add more).
-  Placement: 2, //          0b00000010
-  Update: 4, //             0b00000100
-  PlacementAndUpdate: 6, // 0b00000110
-  Deletion: 8, //           0b00001000
-  ContentReset: 16, //      0b00010000
-  Callback: 32, //          0b00100000
-  Err: 64, //               0b01000000
-  Ref: 128, //              0b10000000
-};
+// Don't change these two values:
+export const NoEffect = 0; //           0b00000000
+export const PerformedWork = 1; //      0b00000001
+// You can change the rest (and add more).
+export const Placement = 2; //          0b00000010
+export const Update = 4; //             0b00000100
+export const PlacementAndUpdate = 6; // 0b00000110
+export const Deletion = 8; //           0b00001000
+export const ContentReset = 16; //      0b00010000
+export const Callback = 32; //          0b00100000
+export const Err = 64; //               0b01000000
+export const Ref = 128; //              0b10000000
diff --git a/src/renderers/shared/fiber/isomorphic/ReactCoroutine.js b/src/renderers/shared/fiber/isomorphic/ReactCoroutine.js
index 3ce87530e10..5ffede64b9e 100644
--- a/src/renderers/shared/fiber/isomorphic/ReactCoroutine.js
+++ b/src/renderers/shared/fiber/isomorphic/ReactCoroutine.js
@@ -16,8 +16,8 @@ import type {ReactCoroutine, ReactNodeList, ReactYield} from 'ReactTypes';
 
 // The Symbol used to tag the special React types. If there is no native Symbol
 // nor polyfill, then a plain number is used for performance.
-var REACT_COROUTINE_TYPE;
-var REACT_YIELD_TYPE;
+export let REACT_COROUTINE_TYPE;
+export let REACT_YIELD_TYPE;
 if (typeof Symbol === 'function' && Symbol.for) {
   REACT_COROUTINE_TYPE = Symbol.for('react.coroutine');
   REACT_YIELD_TYPE = Symbol.for('react.yield');
@@ -28,7 +28,7 @@ if (typeof Symbol === 'function' && Symbol.for) {
 
 type CoroutineHandler<T> = (props: T, yields: Array<mixed>) => ReactNodeList;
 
-exports.createCoroutine = function<T>(
+export function createCoroutine<T>(
   children: mixed,
   handler: CoroutineHandler<T>,
   props: T,
@@ -52,9 +52,9 @@ exports.createCoroutine = function<T>(
   }
 
   return coroutine;
-};
+}
 
-exports.createYield = function(value: mixed): ReactYield {
+export function createYield(value: mixed): ReactYield {
   var yieldNode = {
     // This tag allow us to uniquely identify this as a React Yield
     $$typeof: REACT_YIELD_TYPE,
@@ -69,29 +69,26 @@ exports.createYield = function(value: mixed): ReactYield {
   }
 
   return yieldNode;
-};
+}
 
 /**
  * Verifies the object is a coroutine object.
  */
-exports.isCoroutine = function(object: mixed): boolean {
+export function isCoroutine(object: mixed): boolean {
   return (
     typeof object === 'object' &&
     object !== null &&
     object.$$typeof === REACT_COROUTINE_TYPE
   );
-};
+}
 
 /**
  * Verifies the object is a yield object.
  */
-exports.isYield = function(object: mixed): boolean {
+export function isYield(object: mixed): boolean {
   return (
     typeof object === 'object' &&
     object !== null &&
     object.$$typeof === REACT_YIELD_TYPE
   );
-};
-
-exports.REACT_YIELD_TYPE = REACT_YIELD_TYPE;
-exports.REACT_COROUTINE_TYPE = REACT_COROUTINE_TYPE;
+}
diff --git a/src/renderers/shared/fiber/isomorphic/ReactPortal.js b/src/renderers/shared/fiber/isomorphic/ReactPortal.js
index 78198e099d6..a187c3cce12 100644
--- a/src/renderers/shared/fiber/isomorphic/ReactPortal.js
+++ b/src/renderers/shared/fiber/isomorphic/ReactPortal.js
@@ -16,11 +16,11 @@ import type {ReactNodeList, ReactPortal} from 'ReactTypes';
 
 // The Symbol used to tag the special React types. If there is no native Symbol
 // nor polyfill, then a plain number is used for performance.
-var REACT_PORTAL_TYPE =
+export const REACT_PORTAL_TYPE =
   (typeof Symbol === 'function' && Symbol.for && Symbol.for('react.portal')) ||
   0xeaca;
 
-exports.createPortal = function(
+export function createPortal(
   children: ReactNodeList,
   containerInfo: any,
   // TODO: figure out the API for cross-renderer implementation.
@@ -35,17 +35,15 @@ exports.createPortal = function(
     containerInfo,
     implementation,
   };
-};
+}
 
 /**
  * Verifies the object is a portal object.
  */
-exports.isPortal = function(object: mixed): boolean {
+export function isPortal(object: mixed): boolean {
   return (
     typeof object === 'object' &&
     object !== null &&
     object.$$typeof === REACT_PORTAL_TYPE
   );
-};
-
-exports.REACT_PORTAL_TYPE = REACT_PORTAL_TYPE;
+}
diff --git a/src/renderers/shared/hooks/ReactHostOperationHistoryHook.js b/src/renderers/shared/hooks/ReactHostOperationHistoryHook.js
deleted file mode 100644
index 08da2d68c12..00000000000
--- a/src/renderers/shared/hooks/ReactHostOperationHistoryHook.js
+++ /dev/null
@@ -1,54 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactHostOperationHistoryHook
- * @flow
- */
-
-'use strict';
-
-import type {DebugID} from 'ReactInstanceType';
-
-export type Operation = {instanceID: DebugID} & (
-  | {type: 'mount', payload: string}
-  | {type: 'insert child', payload: {toIndex: number, content: string}}
-  | {type: 'move child', payload: {fromIndex: number, toIndex: number}}
-  | {type: 'replace children', payload: string}
-  | {type: 'replace text', payload: string}
-  | {type: 'replace with', payload: string}
-  | {type: 'update styles', payload: mixed /* Style Object */}
-  | {type: 'update attribute', payload: {[name: string]: string}}
-  | {type: 'remove attribute', payload: string});
-
-// Trust the developer to only use this with a __DEV__ check
-var ReactHostOperationHistoryHook = ((null: any): typeof ReactHostOperationHistoryHook);
-
-if (__DEV__) {
-  var history: Array<Operation> = [];
-
-  ReactHostOperationHistoryHook = {
-    onHostOperation(operation: Operation) {
-      history.push(operation);
-    },
-
-    clearHistory(): void {
-      if (ReactHostOperationHistoryHook._preventClearing) {
-        // Should only be used for tests.
-        return;
-      }
-
-      history = [];
-    },
-
-    getHistory(): Array<Operation> {
-      return history;
-    },
-  };
-}
-
-module.exports = ReactHostOperationHistoryHook;
diff --git a/src/renderers/shared/hooks/ReactInvalidSetStateWarningHook.js b/src/renderers/shared/hooks/ReactInvalidSetStateWarningHook.js
deleted file mode 100644
index 53b004a7d01..00000000000
--- a/src/renderers/shared/hooks/ReactInvalidSetStateWarningHook.js
+++ /dev/null
@@ -1,41 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactInvalidSetStateWarningHook
- * @flow
- */
-
-'use strict';
-
-var ReactInvalidSetStateWarningHook = {};
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var processingChildContext = false;
-
-  var warnInvalidSetState = function() {
-    warning(
-      !processingChildContext,
-      'setState(...): Cannot call setState() inside getChildContext()',
-    );
-  };
-
-  ReactInvalidSetStateWarningHook = {
-    onBeginProcessingChildContext(): void {
-      processingChildContext = true;
-    },
-    onEndProcessingChildContext(): void {
-      processingChildContext = false;
-    },
-    onSetState(): void {
-      warnInvalidSetState();
-    },
-  };
-}
-
-module.exports = ReactInvalidSetStateWarningHook;
diff --git a/src/renderers/shared/server/ReactPartialRenderer.js b/src/renderers/shared/server/ReactPartialRenderer.js
index 64cdb8109b9..4929891677a 100644
--- a/src/renderers/shared/server/ReactPartialRenderer.js
+++ b/src/renderers/shared/server/ReactPartialRenderer.js
@@ -11,46 +11,52 @@
 
 'use strict';
 
-var {
+import {
   Namespaces,
   getIntrinsicNamespace,
   getChildNamespace,
-} = require('DOMNamespaces');
-var DOMMarkupOperations = require('DOMMarkupOperations');
-var React = require('react');
-var ReactControlledValuePropTypes = require('ReactControlledValuePropTypes');
-
-var assertValidProps = require('assertValidProps');
-var dangerousStyleValue = require('dangerousStyleValue');
-var emptyObject = require('fbjs/lib/emptyObject');
-var escapeTextContentForBrowser = require('escapeTextContentForBrowser');
-var hyphenateStyleName = require('fbjs/lib/hyphenateStyleName');
-var invariant = require('fbjs/lib/invariant');
-var memoizeStringOnly = require('fbjs/lib/memoizeStringOnly');
-var omittedCloseTags = require('omittedCloseTags');
+} from 'DOMNamespaces';
+import {
+  createMarkupForCustomAttribute,
+  createMarkupForProperty,
+  createMarkupForRoot,
+} from 'DOMMarkupOperations';
+import React from 'react';
+import {
+  checkPropTypes as checkControlledValuePropTypes,
+} from 'ReactControlledValuePropTypes';
+import assertValidProps from 'assertValidProps';
+import dangerousStyleValue from 'dangerousStyleValue';
+import emptyObject from 'fbjs/lib/emptyObject';
+import escapeTextContentForBrowser from 'escapeTextContentForBrowser';
+import hyphenateStyleName from 'fbjs/lib/hyphenateStyleName';
+import invariant from 'fbjs/lib/invariant';
+import memoizeStringOnly from 'fbjs/lib/memoizeStringOnly';
+import omittedCloseTags from 'omittedCloseTags';
+import warning from 'fbjs/lib/warning';
+import checkPropTypes from 'prop-types/checkPropTypes';
+import warnValidStyle from 'warnValidStyle';
+import {
+  validateProperties as validateARIAProperties,
+} from 'ReactDOMInvalidARIAHook';
+import {
+  validateProperties as validateInputPropertes,
+} from 'ReactDOMNullInputValuePropHook';
+import {
+  validateProperties as validateUnknownPropertes,
+} from 'ReactDOMUnknownPropertyHook';
+import describeComponentFrame from 'describeComponentFrame';
+import {ReactDebugCurrentFrame} from 'ReactGlobalSharedState';
 
 var toArray = React.Children.toArray;
 
 if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var checkPropTypes = require('prop-types/checkPropTypes');
-  var warnValidStyle = require('warnValidStyle');
-  var {
-    validateProperties: validateARIAProperties,
-  } = require('ReactDOMInvalidARIAHook');
-  var {
-    validateProperties: validateInputPropertes,
-  } = require('ReactDOMNullInputValuePropHook');
-  var {
-    validateProperties: validateUnknownPropertes,
-  } = require('ReactDOMUnknownPropertyHook');
   var validatePropertiesInDevelopment = function(type, props) {
     validateARIAProperties(type, props);
     validateInputPropertes(type, props);
     validateUnknownPropertes(type, props);
   };
 
-  var describeComponentFrame = require('describeComponentFrame');
   var describeStackFrame = function(element): string {
     var source = element._source;
     var type = element.type;
@@ -59,7 +65,6 @@ if (__DEV__) {
     return describeComponentFrame(name, source, ownerName);
   };
 
-  var {ReactDebugCurrentFrame} = require('ReactGlobalSharedState');
   var currentDebugStack = null;
   var currentDebugElementStack = null;
   var setCurrentDebugStack = function(stack) {
@@ -67,7 +72,7 @@ if (__DEV__) {
     // We are about to enter a new composite stack, reset the array.
     currentDebugElementStack.length = 0;
     currentDebugStack = stack;
-    ReactDebugCurrentFrame.getCurrentStack = getStackAddendum;
+    ReactDebugCurrentFrame.setCurrentStackImplementation(getStackAddendum);
   };
   var pushElementToDebugStack = function(element) {
     if (currentDebugElementStack !== null) {
@@ -77,7 +82,7 @@ if (__DEV__) {
   var resetCurrentDebugStack = function() {
     currentDebugElementStack = null;
     currentDebugStack = null;
-    ReactDebugCurrentFrame.getCurrentStack = null;
+    ReactDebugCurrentFrame.setCurrentStackImplementation(null);
   };
   var getStackAddendum = function(): null | string {
     if (currentDebugStack === null) {
@@ -282,13 +287,10 @@ function createOpenTagMarkup(
     var markup = null;
     if (isCustomComponent(tagLowercase, props)) {
       if (!RESERVED_PROPS.hasOwnProperty(propKey)) {
-        markup = DOMMarkupOperations.createMarkupForCustomAttribute(
-          propKey,
-          propValue,
-        );
+        markup = createMarkupForCustomAttribute(propKey, propValue);
       }
     } else {
-      markup = DOMMarkupOperations.createMarkupForProperty(propKey, propValue);
+      markup = createMarkupForProperty(propKey, propValue);
     }
     if (markup) {
       ret += ' ' + markup;
@@ -302,7 +304,7 @@ function createOpenTagMarkup(
   }
 
   if (isRootElement) {
-    ret += ' ' + DOMMarkupOperations.createMarkupForRoot();
+    ret += ' ' + createMarkupForRoot();
   }
   return ret;
 }
@@ -444,7 +446,7 @@ function resolve(child, context) {
   return {child, context};
 }
 
-class ReactDOMServerRenderer {
+export default class ReactDOMServerRenderer {
   constructor(element, makeStaticMarkup) {
     var children = React.isValidElement(element) ? [element] : toArray(element);
     var topFrame = {
@@ -566,7 +568,7 @@ class ReactDOMServerRenderer {
     var props = element.props;
     if (tag === 'input') {
       if (__DEV__) {
-        ReactControlledValuePropTypes.checkPropTypes(
+        checkControlledValuePropTypes(
           'input',
           props,
           () => '', //getCurrentFiberStackAddendum
@@ -624,7 +626,7 @@ class ReactDOMServerRenderer {
       );
     } else if (tag === 'textarea') {
       if (__DEV__) {
-        ReactControlledValuePropTypes.checkPropTypes(
+        checkControlledValuePropTypes(
           'textarea',
           props,
           () => '', //getCurrentFiberStackAddendum
@@ -685,7 +687,7 @@ class ReactDOMServerRenderer {
       });
     } else if (tag === 'select') {
       if (__DEV__) {
-        ReactControlledValuePropTypes.checkPropTypes(
+        checkControlledValuePropTypes(
           'select',
           props,
           () => '', // getCurrentFiberStackAddendum,
@@ -833,5 +835,3 @@ class ReactDOMServerRenderer {
     return out;
   }
 }
-
-module.exports = ReactDOMServerRenderer;
diff --git a/src/renderers/shared/shared/ReactInstanceMap.js b/src/renderers/shared/shared/ReactInstanceMap.js
index c26c3c959a1..e8d073eb585 100644
--- a/src/renderers/shared/shared/ReactInstanceMap.js
+++ b/src/renderers/shared/shared/ReactInstanceMap.js
@@ -42,4 +42,4 @@ var ReactInstanceMap = {
   },
 };
 
-module.exports = ReactInstanceMap;
+export default ReactInstanceMap;
diff --git a/src/renderers/shared/shared/ReactTreeTraversal.js b/src/renderers/shared/shared/ReactTreeTraversal.js
index c6c8aa26561..f0badc96bc9 100644
--- a/src/renderers/shared/shared/ReactTreeTraversal.js
+++ b/src/renderers/shared/shared/ReactTreeTraversal.js
@@ -11,24 +11,19 @@
 
 'use strict';
 
-var {HostComponent} = require('ReactTypeOfWork');
+import {HostComponent} from 'ReactTypeOfWork';
 
 function getParent(inst) {
-  if (inst._hostParent !== undefined) {
-    return inst._hostParent;
-  }
-  if (typeof inst.tag === 'number') {
-    do {
-      inst = inst.return;
-      // TODO: If this is a HostRoot we might want to bail out.
-      // That is depending on if we want nested subtrees (layers) to bubble
-      // events to their parent. We could also go through parentNode on the
-      // host node but that wouldn't work for React Native and doesn't let us
-      // do the portal feature.
-    } while (inst && inst.tag !== HostComponent);
-    if (inst) {
-      return inst;
-    }
+  do {
+    inst = inst.return;
+    // TODO: If this is a HostRoot we might want to bail out.
+    // That is depending on if we want nested subtrees (layers) to bubble
+    // events to their parent. We could also go through parentNode on the
+    // host node but that wouldn't work for React Native and doesn't let us
+    // do the portal feature.
+  } while (inst && inst.tag !== HostComponent);
+  if (inst) {
+    return inst;
   }
   return null;
 }
@@ -37,7 +32,7 @@ function getParent(inst) {
  * Return the lowest common ancestor of A and B, or null if they are in
  * different trees.
  */
-function getLowestCommonAncestor(instA, instB) {
+export function getLowestCommonAncestor(instA, instB) {
   var depthA = 0;
   for (var tempA = instA; tempA; tempA = getParent(tempA)) {
     depthA++;
@@ -74,7 +69,7 @@ function getLowestCommonAncestor(instA, instB) {
 /**
  * Return if A is an ancestor of B.
  */
-function isAncestor(instA, instB) {
+export function isAncestor(instA, instB) {
   while (instB) {
     if (instA === instB || instA === instB.alternate) {
       return true;
@@ -87,14 +82,14 @@ function isAncestor(instA, instB) {
 /**
  * Return the parent instance of the passed-in instance.
  */
-function getParentInstance(inst) {
+export function getParentInstance(inst) {
   return getParent(inst);
 }
 
 /**
  * Simulates the traversal of a two-phase, capture/bubble event dispatch.
  */
-function traverseTwoPhase(inst, fn, arg) {
+export function traverseTwoPhase(inst, fn, arg) {
   var path = [];
   while (inst) {
     path.push(inst);
@@ -116,7 +111,7 @@ function traverseTwoPhase(inst, fn, arg) {
  * Does not invoke the callback on the nearest common ancestor because nothing
  * "entered" or "left" that element.
  */
-function traverseEnterLeave(from, to, fn, argFrom, argTo) {
+export function traverseEnterLeave(from, to, fn, argFrom, argTo) {
   var common = from && to ? getLowestCommonAncestor(from, to) : null;
   var pathFrom = [];
   while (from && from !== common) {
@@ -136,11 +131,3 @@ function traverseEnterLeave(from, to, fn, argFrom, argTo) {
     fn(pathTo[i], 'captured', argTo);
   }
 }
-
-module.exports = {
-  isAncestor: isAncestor,
-  getLowestCommonAncestor: getLowestCommonAncestor,
-  getParentInstance: getParentInstance,
-  traverseTwoPhase: traverseTwoPhase,
-  traverseEnterLeave: traverseEnterLeave,
-};
diff --git a/src/renderers/shared/shared/event/BrowserEventConstants.js b/src/renderers/shared/shared/event/BrowserEventConstants.js
index 0f460486be7..848385da99b 100644
--- a/src/renderers/shared/shared/event/BrowserEventConstants.js
+++ b/src/renderers/shared/shared/event/BrowserEventConstants.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var getVendorPrefixedEventName = require('getVendorPrefixedEventName');
+import getVendorPrefixedEventName from 'getVendorPrefixedEventName';
 
 /**
  * Types of raw signals from the browser caught at the top level.
@@ -20,7 +20,7 @@ var getVendorPrefixedEventName = require('getVendorPrefixedEventName');
  * trap at a lower node than `document`), binding at `document` would
  * cause duplicate events so we don't include them here.
  */
-var topLevelTypes = {
+export const topLevelTypes = {
   topAbort: 'abort',
   topAnimationEnd: getVendorPrefixedEventName('animationend') || 'animationend',
   topAnimationIteration: getVendorPrefixedEventName('animationiteration') ||
@@ -95,9 +95,3 @@ var topLevelTypes = {
 };
 
 export type TopLevelTypes = $Enum<typeof topLevelTypes>;
-
-var BrowserEventConstants = {
-  topLevelTypes,
-};
-
-module.exports = BrowserEventConstants;
diff --git a/src/renderers/shared/shared/event/EventPluginHub.js b/src/renderers/shared/shared/event/EventPluginHub.js
index 20f34c8a8b7..1be3fc84249 100644
--- a/src/renderers/shared/shared/event/EventPluginHub.js
+++ b/src/renderers/shared/shared/event/EventPluginHub.js
@@ -11,13 +11,16 @@
 
 'use strict';
 
-var EventPluginRegistry = require('EventPluginRegistry');
-var EventPluginUtils = require('EventPluginUtils');
-var ReactErrorUtils = require('ReactErrorUtils');
+import {plugins} from 'EventPluginRegistry';
+import {
+  executeDispatchesInOrder,
+  getFiberCurrentPropsFromNode,
+} from 'EventPluginUtils';
+import ReactErrorUtils from 'ReactErrorUtils';
 
-var accumulateInto = require('accumulateInto');
-var forEachAccumulated = require('forEachAccumulated');
-var invariant = require('fbjs/lib/invariant');
+import accumulateInto from 'accumulateInto';
+import forEachAccumulated from 'forEachAccumulated';
+import invariant from 'fbjs/lib/invariant';
 
 /**
  * Internal queue of events that have accumulated their dispatches and are
@@ -34,7 +37,7 @@ var eventQueue = null;
  */
 var executeDispatchesAndRelease = function(event, simulated) {
   if (event) {
-    EventPluginUtils.executeDispatchesInOrder(event, simulated);
+    executeDispatchesInOrder(event, simulated);
 
     if (!event.isPersistent()) {
       event.constructor.release(event);
@@ -97,154 +100,111 @@ function shouldPreventMouseEvent(name, type, props) {
  *
  * @public
  */
-var EventPluginHub = {
-  /**
-   * Methods for injecting dependencies.
-   */
-  injection: {
-    /**
-     * @param {array} InjectedEventPluginOrder
-     * @public
-     */
-    injectEventPluginOrder: EventPluginRegistry.injectEventPluginOrder,
 
-    /**
-     * @param {object} injectedNamesToPlugins Map from names to plugin modules.
-     */
-    injectEventPluginsByName: EventPluginRegistry.injectEventPluginsByName,
-  },
-
-  /**
-   * @param {object} inst The instance, which is the source of events.
-   * @param {string} registrationName Name of listener (e.g. `onClick`).
-   * @return {?function} The stored callback.
-   */
-  getListener: function(inst, registrationName) {
-    var listener;
-
-    // TODO: shouldPreventMouseEvent is DOM-specific and definitely should not
-    // live here; needs to be moved to a better place soon
-    if (typeof inst.tag === 'number') {
-      const stateNode = inst.stateNode;
-      if (!stateNode) {
-        // Work in progress (ex: onload events in incremental mode).
-        return null;
-      }
-      const props = EventPluginUtils.getFiberCurrentPropsFromNode(stateNode);
-      if (!props) {
-        // Work in progress.
-        return null;
-      }
-      listener = props[registrationName];
-      if (shouldPreventMouseEvent(registrationName, inst.type, props)) {
-        return null;
-      }
-    } else {
-      const currentElement = inst._currentElement;
-      if (
-        typeof currentElement === 'string' ||
-        typeof currentElement === 'number'
-      ) {
-        // Text node, let it bubble through.
-        return null;
-      }
-      if (!inst._rootNodeID) {
-        // If the instance is already unmounted, we have no listeners.
-        return null;
-      }
-      const props = currentElement.props;
-      listener = props[registrationName];
-      if (
-        shouldPreventMouseEvent(registrationName, currentElement.type, props)
-      ) {
-        return null;
-      }
-    }
-
-    invariant(
-      !listener || typeof listener === 'function',
-      'Expected `%s` listener to be a function, instead got a value of `%s` type.',
-      registrationName,
-      typeof listener,
-    );
-    return listener;
-  },
+/**
+ * @param {object} inst The instance, which is the source of events.
+ * @param {string} registrationName Name of listener (e.g. `onClick`).
+ * @return {?function} The stored callback.
+ */
+export function getListener(inst, registrationName) {
+  var listener;
+
+  // TODO: shouldPreventMouseEvent is DOM-specific and definitely should not
+  // live here; needs to be moved to a better place soon
+  const stateNode = inst.stateNode;
+  if (!stateNode) {
+    // Work in progress (ex: onload events in incremental mode).
+    return null;
+  }
+  const props = getFiberCurrentPropsFromNode(stateNode);
+  if (!props) {
+    // Work in progress.
+    return null;
+  }
+  listener = props[registrationName];
+  if (shouldPreventMouseEvent(registrationName, inst.type, props)) {
+    return null;
+  }
+  invariant(
+    !listener || typeof listener === 'function',
+    'Expected `%s` listener to be a function, instead got a value of `%s` type.',
+    registrationName,
+    typeof listener,
+  );
+  return listener;
+}
 
-  /**
-   * Allows registered plugins an opportunity to extract events from top-level
-   * native browser events.
-   *
-   * @return {*} An accumulation of synthetic events.
-   * @internal
-   */
-  extractEvents: function(
-    topLevelType,
-    targetInst,
-    nativeEvent,
-    nativeEventTarget,
-  ) {
-    var events;
-    var plugins = EventPluginRegistry.plugins;
-    for (var i = 0; i < plugins.length; i++) {
-      // Not every plugin in the ordering may be loaded at runtime.
-      var possiblePlugin = plugins[i];
-      if (possiblePlugin) {
-        var extractedEvents = possiblePlugin.extractEvents(
-          topLevelType,
-          targetInst,
-          nativeEvent,
-          nativeEventTarget,
-        );
-        if (extractedEvents) {
-          events = accumulateInto(events, extractedEvents);
-        }
+/**
+ * Allows registered plugins an opportunity to extract events from top-level
+ * native browser events.
+ *
+ * @return {*} An accumulation of synthetic events.
+ * @internal
+ */
+export function extractEvents(
+  topLevelType,
+  targetInst,
+  nativeEvent,
+  nativeEventTarget,
+) {
+  var events;
+  for (var i = 0; i < plugins.length; i++) {
+    // Not every plugin in the ordering may be loaded at runtime.
+    var possiblePlugin = plugins[i];
+    if (possiblePlugin) {
+      var extractedEvents = possiblePlugin.extractEvents(
+        topLevelType,
+        targetInst,
+        nativeEvent,
+        nativeEventTarget,
+      );
+      if (extractedEvents) {
+        events = accumulateInto(events, extractedEvents);
       }
     }
-    return events;
-  },
+  }
+  return events;
+}
 
-  /**
-   * Enqueues a synthetic event that should be dispatched when
-   * `processEventQueue` is invoked.
-   *
-   * @param {*} events An accumulation of synthetic events.
-   * @internal
-   */
-  enqueueEvents: function(events) {
-    if (events) {
-      eventQueue = accumulateInto(eventQueue, events);
-    }
-  },
+/**
+ * Enqueues a synthetic event that should be dispatched when
+ * `processEventQueue` is invoked.
+ *
+ * @param {*} events An accumulation of synthetic events.
+ * @internal
+ */
+export function enqueueEvents(events) {
+  if (events) {
+    eventQueue = accumulateInto(eventQueue, events);
+  }
+}
 
-  /**
-   * Dispatches all synthetic events on the event queue.
-   *
-   * @internal
-   */
-  processEventQueue: function(simulated) {
-    // Set `eventQueue` to null before processing it so that we can tell if more
-    // events get enqueued while processing.
-    var processingEventQueue = eventQueue;
-    eventQueue = null;
-    if (simulated) {
-      forEachAccumulated(
-        processingEventQueue,
-        executeDispatchesAndReleaseSimulated,
-      );
-    } else {
-      forEachAccumulated(
-        processingEventQueue,
-        executeDispatchesAndReleaseTopLevel,
-      );
-    }
-    invariant(
-      !eventQueue,
-      'processEventQueue(): Additional events were enqueued while processing ' +
-        'an event queue. Support for this has not yet been implemented.',
+/**
+ * Dispatches all synthetic events on the event queue.
+ *
+ * @internal
+ */
+export function processEventQueue(simulated) {
+  // Set `eventQueue` to null before processing it so that we can tell if more
+  // events get enqueued while processing.
+  var processingEventQueue = eventQueue;
+  eventQueue = null;
+  if (simulated) {
+    forEachAccumulated(
+      processingEventQueue,
+      executeDispatchesAndReleaseSimulated,
     );
-    // This would be a good time to rethrow if any of the event handlers threw.
-    ReactErrorUtils.rethrowCaughtError();
-  },
-};
-
-module.exports = EventPluginHub;
+  } else {
+    forEachAccumulated(
+      processingEventQueue,
+      executeDispatchesAndReleaseTopLevel,
+    );
+  }
+  invariant(
+    !eventQueue,
+    'processEventQueue(): Additional events were enqueued while processing ' +
+      'an event queue. Support for this has not yet been implemented.',
+  );
+  // This would be a good time to rethrow if any of the event handlers threw.
+  ReactErrorUtils.rethrowCaughtError();
+}
diff --git a/src/renderers/shared/shared/event/EventPluginRegistry.js b/src/renderers/shared/shared/event/EventPluginRegistry.js
index f3359d0d993..2b719373773 100644
--- a/src/renderers/shared/shared/event/EventPluginRegistry.js
+++ b/src/renderers/shared/shared/event/EventPluginRegistry.js
@@ -20,7 +20,7 @@ type NamesToPlugins = {[key: PluginName]: PluginModule<AnyNativeEvent>};
 
 type EventPluginOrder = null | Array<PluginName>;
 
-var invariant = require('fbjs/lib/invariant');
+import invariant from 'fbjs/lib/invariant';
 
 /**
  * Injectable ordering of event plugins.
@@ -51,7 +51,7 @@ function recomputePluginOrdering(): void {
         'the plugin ordering, `%s`.',
       pluginName,
     );
-    if (EventPluginRegistry.plugins[pluginIndex]) {
+    if (plugins[pluginIndex]) {
       continue;
     }
     invariant(
@@ -60,7 +60,7 @@ function recomputePluginOrdering(): void {
         'method, but `%s` does not.',
       pluginName,
     );
-    EventPluginRegistry.plugins[pluginIndex] = pluginModule;
+    plugins[pluginIndex] = pluginModule;
     var publishedEvents = pluginModule.eventTypes;
     for (var eventName in publishedEvents) {
       invariant(
@@ -91,12 +91,12 @@ function publishEventForPlugin(
   eventName: string,
 ): boolean {
   invariant(
-    !EventPluginRegistry.eventNameDispatchConfigs.hasOwnProperty(eventName),
+    !eventNameDispatchConfigs.hasOwnProperty(eventName),
     'EventPluginHub: More than one plugin attempted to publish the same ' +
       'event name, `%s`.',
     eventName,
   );
-  EventPluginRegistry.eventNameDispatchConfigs[eventName] = dispatchConfig;
+  eventNameDispatchConfigs[eventName] = dispatchConfig;
 
   var phasedRegistrationNames = dispatchConfig.phasedRegistrationNames;
   if (phasedRegistrationNames) {
@@ -135,23 +135,21 @@ function publishRegistrationName(
   eventName: string,
 ): void {
   invariant(
-    !EventPluginRegistry.registrationNameModules[registrationName],
+    !registrationNameModules[registrationName],
     'EventPluginHub: More than one plugin attempted to publish the same ' +
       'registration name, `%s`.',
     registrationName,
   );
-  EventPluginRegistry.registrationNameModules[registrationName] = pluginModule;
-  EventPluginRegistry.registrationNameDependencies[registrationName] =
+  registrationNameModules[registrationName] = pluginModule;
+  registrationNameDependencies[registrationName] =
     pluginModule.eventTypes[eventName].dependencies;
 
   if (__DEV__) {
     var lowerCasedName = registrationName.toLowerCase();
-    EventPluginRegistry.possibleRegistrationNames[
-      lowerCasedName
-    ] = registrationName;
+    possibleRegistrationNames[lowerCasedName] = registrationName;
 
     if (registrationName === 'onDoubleClick') {
-      EventPluginRegistry.possibleRegistrationNames.ondblclick = registrationName;
+      possibleRegistrationNames.ondblclick = registrationName;
     }
   }
 }
@@ -161,36 +159,37 @@ function publishRegistrationName(
  *
  * @see {EventPluginHub}
  */
-var EventPluginRegistry = {
-  /**
-   * Ordered list of injected plugins.
-   */
-  plugins: [],
 
-  /**
-   * Mapping from event name to dispatch config
-   */
-  eventNameDispatchConfigs: {},
+/**
+ * Ordered list of injected plugins.
+ */
+export const plugins = [];
 
-  /**
-   * Mapping from registration name to plugin module
-   */
-  registrationNameModules: {},
+/**
+ * Mapping from event name to dispatch config
+ */
+export const eventNameDispatchConfigs = {};
 
-  /**
-   * Mapping from registration name to event name
-   */
-  registrationNameDependencies: {},
+/**
+ * Mapping from registration name to plugin module
+ */
+export const registrationNameModules = {};
 
-  /**
-   * Mapping from lowercase registration names to the properly cased version,
-   * used to warn in the case of missing event handlers. Available
-   * only in __DEV__.
-   * @type {Object}
-   */
-  possibleRegistrationNames: __DEV__ ? {} : (null: any),
-  // Trust the developer to only use possibleRegistrationNames in __DEV__
+/**
+ * Mapping from registration name to event name
+ */
+export const registrationNameDependencies = {};
 
+/**
+ * Mapping from lowercase registration names to the properly cased version,
+ * used to warn in the case of missing event handlers. Available
+ * only in __DEV__.
+ * @type {Object}
+ */
+export const possibleRegistrationNames = __DEV__ ? {} : (null: any);
+// Trust the developer to only use possibleRegistrationNames in __DEV__
+
+export const injection = {
   /**
    * Injects an ordering of plugins (by plugin name). This allows the ordering
    * to be decoupled from injection of the actual plugins so that ordering is
@@ -200,9 +199,7 @@ var EventPluginRegistry = {
    * @internal
    * @see {EventPluginHub.injection.injectEventPluginOrder}
    */
-  injectEventPluginOrder: function(
-    injectedEventPluginOrder: EventPluginOrder,
-  ): void {
+  injectEventPluginOrder(injectedEventPluginOrder: EventPluginOrder): void {
     invariant(
       !eventPluginOrder,
       'EventPluginRegistry: Cannot inject event plugin ordering more than ' +
@@ -223,9 +220,7 @@ var EventPluginRegistry = {
    * @internal
    * @see {EventPluginHub.injection.injectEventPluginsByName}
    */
-  injectEventPluginsByName: function(
-    injectedNamesToPlugins: NamesToPlugins,
-  ): void {
+  injectEventPluginsByName(injectedNamesToPlugins: NamesToPlugins): void {
     var isOrderingDirty = false;
     for (var pluginName in injectedNamesToPlugins) {
       if (!injectedNamesToPlugins.hasOwnProperty(pluginName)) {
@@ -251,5 +246,3 @@ var EventPluginRegistry = {
     }
   },
 };
-
-module.exports = EventPluginRegistry;
diff --git a/src/renderers/shared/shared/event/EventPluginUtils.js b/src/renderers/shared/shared/event/EventPluginUtils.js
index bf9264921dd..bec6bc3ff1c 100644
--- a/src/renderers/shared/shared/event/EventPluginUtils.js
+++ b/src/renderers/shared/shared/event/EventPluginUtils.js
@@ -11,13 +11,9 @@
 
 'use strict';
 
-var ReactErrorUtils = require('ReactErrorUtils');
-
-var invariant = require('fbjs/lib/invariant');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import ReactErrorUtils from 'ReactErrorUtils';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
 
 /**
  * Injected dependencies:
@@ -28,22 +24,22 @@ if (__DEV__) {
  *   and actual node references.
  */
 var ComponentTree;
-var injection = {
-  injectComponentTree: function(Injected) {
+export const injection = {
+  injectComponentTree(Injected) {
     ComponentTree = Injected;
     if (__DEV__) {
       warning(
         Injected &&
           Injected.getNodeFromInstance &&
           Injected.getInstanceFromNode,
-        'EventPluginUtils.injection.injectComponentTree(...): Injected ' +
+        'injection.injectComponentTree(...): Injected ' +
           'module is missing getNodeFromInstance or getInstanceFromNode.',
       );
     }
   },
 };
 
-function isEndish(topLevelType) {
+export function isEndish(topLevelType) {
   return (
     topLevelType === 'topMouseUp' ||
     topLevelType === 'topTouchEnd' ||
@@ -51,10 +47,10 @@ function isEndish(topLevelType) {
   );
 }
 
-function isMoveish(topLevelType) {
+export function isMoveish(topLevelType) {
   return topLevelType === 'topMouseMove' || topLevelType === 'topTouchMove';
 }
-function isStartish(topLevelType) {
+export function isStartish(topLevelType) {
   return topLevelType === 'topMouseDown' || topLevelType === 'topTouchStart';
 }
 
@@ -90,7 +86,7 @@ if (__DEV__) {
  */
 function executeDispatch(event, simulated, listener, inst) {
   var type = event.type || 'unknown-event';
-  event.currentTarget = EventPluginUtils.getNodeFromInstance(inst);
+  event.currentTarget = getNodeFromInstance(inst);
   ReactErrorUtils.invokeGuardedCallbackAndCatchFirstError(
     type,
     listener,
@@ -103,7 +99,7 @@ function executeDispatch(event, simulated, listener, inst) {
 /**
  * Standard/simple iteration through an event's collected dispatches.
  */
-function executeDispatchesInOrder(event, simulated) {
+export function executeDispatchesInOrder(event, simulated) {
   var dispatchListeners = event._dispatchListeners;
   var dispatchInstances = event._dispatchInstances;
   if (__DEV__) {
@@ -163,7 +159,7 @@ function executeDispatchesInOrderStopAtTrueImpl(event) {
 /**
  * @see executeDispatchesInOrderStopAtTrueImpl
  */
-function executeDispatchesInOrderStopAtTrue(event) {
+export function executeDispatchesInOrderStopAtTrue(event) {
   var ret = executeDispatchesInOrderStopAtTrueImpl(event);
   event._dispatchInstances = null;
   event._dispatchListeners = null;
@@ -179,7 +175,7 @@ function executeDispatchesInOrderStopAtTrue(event) {
  *
  * @return {*} The return value of executing the single dispatch.
  */
-function executeDirectDispatch(event) {
+export function executeDirectDispatch(event) {
   if (__DEV__) {
     validateEventDispatches(event);
   }
@@ -190,7 +186,7 @@ function executeDirectDispatch(event) {
     'executeDirectDispatch(...): Invalid `event`.',
   );
   event.currentTarget = dispatchListener
-    ? EventPluginUtils.getNodeFromInstance(dispatchInstance)
+    ? getNodeFromInstance(dispatchInstance)
     : null;
   var res = dispatchListener ? dispatchListener(event) : null;
   event.currentTarget = null;
@@ -203,34 +199,16 @@ function executeDirectDispatch(event) {
  * @param {SyntheticEvent} event
  * @return {boolean} True iff number of dispatches accumulated is greater than 0.
  */
-function hasDispatches(event) {
+export function hasDispatches(event) {
   return !!event._dispatchListeners;
 }
 
-/**
- * General utilities that are useful in creating custom Event Plugins.
- */
-var EventPluginUtils = {
-  isEndish: isEndish,
-  isMoveish: isMoveish,
-  isStartish: isStartish,
-
-  executeDirectDispatch: executeDirectDispatch,
-  executeDispatchesInOrder: executeDispatchesInOrder,
-  executeDispatchesInOrderStopAtTrue: executeDispatchesInOrderStopAtTrue,
-  hasDispatches: hasDispatches,
-
-  getFiberCurrentPropsFromNode: function(node) {
-    return ComponentTree.getFiberCurrentPropsFromNode(node);
-  },
-  getInstanceFromNode: function(node) {
-    return ComponentTree.getInstanceFromNode(node);
-  },
-  getNodeFromInstance: function(node) {
-    return ComponentTree.getNodeFromInstance(node);
-  },
-
-  injection: injection,
-};
-
-module.exports = EventPluginUtils;
+export function getFiberCurrentPropsFromNode(node) {
+  return ComponentTree.getFiberCurrentPropsFromNode(node);
+}
+export function getInstanceFromNode(node) {
+  return ComponentTree.getInstanceFromNode(node);
+}
+export function getNodeFromInstance(node) {
+  return ComponentTree.getNodeFromInstance(node);
+}
diff --git a/src/renderers/shared/shared/event/EventPropagators.js b/src/renderers/shared/shared/event/EventPropagators.js
index 4a0426548c4..5a304f7bfc8 100644
--- a/src/renderers/shared/shared/event/EventPropagators.js
+++ b/src/renderers/shared/shared/event/EventPropagators.js
@@ -11,20 +11,18 @@
 
 'use strict';
 
-var EventPluginHub = require('EventPluginHub');
-var ReactTreeTraversal = require('ReactTreeTraversal');
-
-var accumulateInto = require('accumulateInto');
-var forEachAccumulated = require('forEachAccumulated');
+import {getListener} from 'EventPluginHub';
+import {
+  getParentInstance,
+  traverseTwoPhase,
+  traverseEnterLeave,
+} from 'ReactTreeTraversal';
+import accumulateInto from 'accumulateInto';
+import forEachAccumulated from 'forEachAccumulated';
+import warning from 'fbjs/lib/warning';
 
 type PropagationPhases = 'bubbled' | 'captured';
 
-var getListener = EventPluginHub.getListener;
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
 /**
  * Some event types have a notion of different registration names for different
  * "phases" of propagation. This finds listeners by a given phase.
@@ -64,11 +62,7 @@ function accumulateDirectionalDispatches(inst, phase, event) {
  */
 function accumulateTwoPhaseDispatchesSingle(event) {
   if (event && event.dispatchConfig.phasedRegistrationNames) {
-    ReactTreeTraversal.traverseTwoPhase(
-      event._targetInst,
-      accumulateDirectionalDispatches,
-      event,
-    );
+    traverseTwoPhase(event._targetInst, accumulateDirectionalDispatches, event);
   }
 }
 
@@ -78,14 +72,8 @@ function accumulateTwoPhaseDispatchesSingle(event) {
 function accumulateTwoPhaseDispatchesSingleSkipTarget(event) {
   if (event && event.dispatchConfig.phasedRegistrationNames) {
     var targetInst = event._targetInst;
-    var parentInst = targetInst
-      ? ReactTreeTraversal.getParentInstance(targetInst)
-      : null;
-    ReactTreeTraversal.traverseTwoPhase(
-      parentInst,
-      accumulateDirectionalDispatches,
-      event,
-    );
+    var parentInst = targetInst ? getParentInstance(targetInst) : null;
+    traverseTwoPhase(parentInst, accumulateDirectionalDispatches, event);
   }
 }
 
@@ -119,28 +107,6 @@ function accumulateDirectDispatchesSingle(event) {
   }
 }
 
-function accumulateTwoPhaseDispatches(events) {
-  forEachAccumulated(events, accumulateTwoPhaseDispatchesSingle);
-}
-
-function accumulateTwoPhaseDispatchesSkipTarget(events) {
-  forEachAccumulated(events, accumulateTwoPhaseDispatchesSingleSkipTarget);
-}
-
-function accumulateEnterLeaveDispatches(leave, enter, from, to) {
-  ReactTreeTraversal.traverseEnterLeave(
-    from,
-    to,
-    accumulateDispatches,
-    leave,
-    enter,
-  );
-}
-
-function accumulateDirectDispatches(events) {
-  forEachAccumulated(events, accumulateDirectDispatchesSingle);
-}
-
 /**
  * A small set of propagation patterns, each of which will accept a small amount
  * of information, and generate a set of "dispatch ready event objects" - which
@@ -149,14 +115,20 @@ function accumulateDirectDispatches(events) {
  * propagation strategies from actually executing the dispatches, since we
  * always want to collect the entire set of dispatches before executing even a
  * single one.
- *
- * @constructor EventPropagators
  */
-var EventPropagators = {
-  accumulateTwoPhaseDispatches: accumulateTwoPhaseDispatches,
-  accumulateTwoPhaseDispatchesSkipTarget: accumulateTwoPhaseDispatchesSkipTarget,
-  accumulateDirectDispatches: accumulateDirectDispatches,
-  accumulateEnterLeaveDispatches: accumulateEnterLeaveDispatches,
-};
 
-module.exports = EventPropagators;
+export function accumulateTwoPhaseDispatches(events) {
+  forEachAccumulated(events, accumulateTwoPhaseDispatchesSingle);
+}
+
+export function accumulateTwoPhaseDispatchesSkipTarget(events) {
+  forEachAccumulated(events, accumulateTwoPhaseDispatchesSingleSkipTarget);
+}
+
+export function accumulateEnterLeaveDispatches(leave, enter, from, to) {
+  traverseEnterLeave(from, to, accumulateDispatches, leave, enter);
+}
+
+export function accumulateDirectDispatches(events) {
+  forEachAccumulated(events, accumulateDirectDispatchesSingle);
+}
diff --git a/src/renderers/shared/shared/event/PluginModuleType.js b/src/renderers/shared/shared/event/PluginModuleType.js
index 5b51f9f7a22..efd565c3847 100644
--- a/src/renderers/shared/shared/event/PluginModuleType.js
+++ b/src/renderers/shared/shared/event/PluginModuleType.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-import type {ReactInstance} from 'ReactInstanceType';
+import type {Fiber} from 'ReactFiber';
 import type {
   DispatchConfig,
   ReactSyntheticEvent,
@@ -28,7 +28,7 @@ export type PluginModule<NativeEvent> = {
   eventTypes: EventTypes,
   extractEvents: (
     topLevelType: string,
-    targetInst: ReactInstance,
+    targetInst: Fiber,
     nativeTarget: NativeEvent,
     nativeEventTarget: EventTarget,
   ) => null | ReactSyntheticEvent,
diff --git a/src/renderers/shared/shared/event/ReactControlledComponent.js b/src/renderers/shared/shared/event/ReactControlledComponent.js
index 2dfd77cbdff..e20d2703534 100644
--- a/src/renderers/shared/shared/event/ReactControlledComponent.js
+++ b/src/renderers/shared/shared/event/ReactControlledComponent.js
@@ -11,90 +11,72 @@
 
 'use strict';
 
-var EventPluginUtils = require('EventPluginUtils');
-
-var invariant = require('fbjs/lib/invariant');
+import {
+  getInstanceFromNode,
+  getFiberCurrentPropsFromNode,
+} from 'EventPluginUtils';
+import invariant from 'fbjs/lib/invariant';
 
 // Use to restore controlled state after a change event has fired.
 
-var fiberHostComponent = null;
-
-var ReactControlledComponentInjection = {
-  injectFiberControlledHostComponent: function(hostComponentImpl) {
-    // The fiber implementation doesn't use dynamic dispatch so we need to
-    // inject the implementation.
-    fiberHostComponent = hostComponentImpl;
-  },
-};
-
+var restoreControlledState = null;
 var restoreTarget = null;
 var restoreQueue = null;
 
 function restoreStateOfTarget(target) {
   // We perform this translation at the end of the event loop so that we
   // always receive the correct fiber here
-  var internalInstance = EventPluginUtils.getInstanceFromNode(target);
+  var internalInstance = getInstanceFromNode(target);
   if (!internalInstance) {
     // Unmounted
     return;
   }
-  if (typeof internalInstance.tag === 'number') {
-    invariant(
-      fiberHostComponent &&
-        typeof fiberHostComponent.restoreControlledState === 'function',
-      'Fiber needs to be injected to handle a fiber target for controlled ' +
-        'events. This error is likely caused by a bug in React. Please file an issue.',
-    );
-    const props = EventPluginUtils.getFiberCurrentPropsFromNode(
-      internalInstance.stateNode,
-    );
-    fiberHostComponent.restoreControlledState(
-      internalInstance.stateNode,
-      internalInstance.type,
-      props,
-    );
-    return;
-  }
   invariant(
-    typeof internalInstance.restoreControlledState === 'function',
-    'The internal instance must be a React host component. ' +
-      'This error is likely caused by a bug in React. Please file an issue.',
+    restoreControlledState === 'function',
+    'Fiber needs to be injected to handle a fiber target for controlled ' +
+      'events. This error is likely caused by a bug in React. Please file an issue.',
+  );
+  const props = getFiberCurrentPropsFromNode(internalInstance.stateNode);
+  restoreControlledState(
+    internalInstance.stateNode,
+    internalInstance.type,
+    props,
   );
-  // If it is not a Fiber, we can just use dynamic dispatch.
-  internalInstance.restoreControlledState();
 }
 
-var ReactControlledComponent = {
-  injection: ReactControlledComponentInjection,
+export const injection = {
+  injectRestoreStateImplementation(restoreImpl) {
+    // The fiber implementation doesn't use dynamic dispatch so we need to
+    // inject the implementation.
+    restoreControlledState = restoreImpl;
+  },
+};
 
-  enqueueStateRestore(target) {
-    if (restoreTarget) {
-      if (restoreQueue) {
-        restoreQueue.push(target);
-      } else {
-        restoreQueue = [target];
-      }
+export function enqueueStateRestore(target) {
+  if (restoreTarget) {
+    if (restoreQueue) {
+      restoreQueue.push(target);
     } else {
-      restoreTarget = target;
+      restoreQueue = [target];
     }
-  },
+  } else {
+    restoreTarget = target;
+  }
+}
 
-  restoreStateIfNeeded() {
-    if (!restoreTarget) {
-      return;
-    }
-    var target = restoreTarget;
-    var queuedTargets = restoreQueue;
-    restoreTarget = null;
-    restoreQueue = null;
+export function restoreStateIfNeeded() {
+  if (!restoreTarget) {
+    return;
+  }
+  var target = restoreTarget;
+  var queuedTargets = restoreQueue;
+  restoreTarget = null;
+  restoreQueue = null;
 
-    restoreStateOfTarget(target);
-    if (queuedTargets) {
-      for (var i = 0; i < queuedTargets.length; i++) {
-        restoreStateOfTarget(queuedTargets[i]);
-      }
+  restoreStateOfTarget(target);
+  if (queuedTargets) {
+    for (var i = 0; i < queuedTargets.length; i++) {
+      restoreStateOfTarget(queuedTargets[i]);
     }
-  },
-};
-
-module.exports = ReactControlledComponent;
+  }
+}
diff --git a/src/renderers/shared/shared/event/ReactEventEmitterMixin.js b/src/renderers/shared/shared/event/ReactEventEmitterMixin.js
index 63134a57e1b..9fc32b7109a 100644
--- a/src/renderers/shared/shared/event/ReactEventEmitterMixin.js
+++ b/src/renderers/shared/shared/event/ReactEventEmitterMixin.js
@@ -11,32 +11,28 @@
 
 'use strict';
 
-var EventPluginHub = require('EventPluginHub');
+import {enqueueEvents, extractEvents, processEventQueue} from 'EventPluginHub';
 
 function runEventQueueInBatch(events) {
-  EventPluginHub.enqueueEvents(events);
-  EventPluginHub.processEventQueue(false);
+  enqueueEvents(events);
+  processEventQueue(false);
 }
 
-var ReactEventEmitterMixin = {
-  /**
+/**
    * Streams a fired top-level event to `EventPluginHub` where plugins have the
    * opportunity to create `ReactEvent`s to be dispatched.
    */
-  handleTopLevel: function(
+export function handleTopLevel(
+  topLevelType,
+  targetInst,
+  nativeEvent,
+  nativeEventTarget,
+) {
+  var events = extractEvents(
     topLevelType,
     targetInst,
     nativeEvent,
     nativeEventTarget,
-  ) {
-    var events = EventPluginHub.extractEvents(
-      topLevelType,
-      targetInst,
-      nativeEvent,
-      nativeEventTarget,
-    );
-    runEventQueueInBatch(events);
-  },
-};
-
-module.exports = ReactEventEmitterMixin;
+  );
+  runEventQueueInBatch(events);
+}
diff --git a/src/renderers/shared/shared/event/ReactGenericBatching.js b/src/renderers/shared/shared/event/ReactGenericBatching.js
index cbb71001ba8..d2d5608969c 100644
--- a/src/renderers/shared/shared/event/ReactGenericBatching.js
+++ b/src/renderers/shared/shared/event/ReactGenericBatching.js
@@ -11,66 +11,42 @@
 
 'use strict';
 
-var ReactControlledComponent = require('ReactControlledComponent');
+import {restoreStateIfNeeded} from 'ReactControlledComponent';
 
-// Used as a way to call batchedUpdates when we don't know if we're in a Fiber
-// or Stack context. Such as when we're dispatching events or if third party
+// Used as a way to call batchedUpdates when we don't have a reference to
+// the renderer. Such as when we're dispatching events or if third party
 // libraries need to call batchedUpdates. Eventually, this API will go away when
 // everything is batched by default. We'll then have a similar API to opt-out of
 // scheduled work and instead do synchronous work.
 
 // Defaults
-var stackBatchedUpdates = function(fn, a, b, c, d, e) {
-  return fn(a, b, c, d, e);
-};
-var fiberBatchedUpdates = function(fn, bookkeeping) {
+var batchedUpdatesImpl = function(fn, bookkeeping) {
   return fn(bookkeeping);
 };
 
-function performFiberBatchedUpdates(fn, bookkeeping) {
-  // If we have Fiber loaded, we need to wrap this in a batching call so that
-  // Fiber can apply its default priority for this call.
-  return fiberBatchedUpdates(fn, bookkeeping);
-}
-function batchedUpdates(fn, bookkeeping) {
-  // We first perform work with the stack batching strategy, by passing our
-  // indirection to it.
-  return stackBatchedUpdates(performFiberBatchedUpdates, fn, bookkeeping);
-}
-
 var isNestingBatched = false;
-function batchedUpdatesWithControlledComponents(fn, bookkeeping) {
+export function batchedUpdates(fn, bookkeeping) {
   if (isNestingBatched) {
     // If we are currently inside another batch, we need to wait until it
     // fully completes before restoring state. Therefore, we add the target to
     // a queue of work.
-    return batchedUpdates(fn, bookkeeping);
+    return batchedUpdatesImpl(fn, bookkeeping);
   }
   isNestingBatched = true;
   try {
-    return batchedUpdates(fn, bookkeeping);
+    return batchedUpdatesImpl(fn, bookkeeping);
   } finally {
     // Here we wait until all updates have propagated, which is important
     // when using controlled components within layers:
     // https://github.com/facebook/react/issues/1698
     // Then we restore state of any controlled component.
     isNestingBatched = false;
-    ReactControlledComponent.restoreStateIfNeeded();
+    restoreStateIfNeeded();
   }
 }
 
-var ReactGenericBatchingInjection = {
-  injectStackBatchedUpdates: function(_batchedUpdates) {
-    stackBatchedUpdates = _batchedUpdates;
+export const injection = {
+  injectBatchedUpdatesImplementation(_batchedUpdates) {
+    batchedUpdatesImpl = _batchedUpdates;
   },
-  injectFiberBatchedUpdates: function(_batchedUpdates) {
-    fiberBatchedUpdates = _batchedUpdates;
-  },
-};
-
-var ReactGenericBatching = {
-  batchedUpdates: batchedUpdatesWithControlledComponents,
-  injection: ReactGenericBatchingInjection,
 };
-
-module.exports = ReactGenericBatching;
diff --git a/src/renderers/shared/shared/event/ReactSyntheticEventType.js b/src/renderers/shared/shared/event/ReactSyntheticEventType.js
index 3496d633c9e..872760d45c6 100644
--- a/src/renderers/shared/shared/event/ReactSyntheticEventType.js
+++ b/src/renderers/shared/shared/event/ReactSyntheticEventType.js
@@ -14,7 +14,7 @@
 
 'use strict';
 
-import type {ReactInstance} from 'ReactInstanceType';
+import type {Fiber} from 'ReactFiber';
 
 export type DispatchConfig = {
   dependencies: Array<string>,
@@ -29,7 +29,7 @@ export type ReactSyntheticEvent = {
   dispatchConfig: DispatchConfig,
   getPooled: (
     dispatchConfig: DispatchConfig,
-    targetInst: ReactInstance,
+    targetInst: Fiber,
     nativeTarget: Event,
     nativeEventTarget: EventTarget,
   ) => ReactSyntheticEvent,
diff --git a/src/renderers/shared/shared/event/SyntheticEvent.js b/src/renderers/shared/shared/event/SyntheticEvent.js
index d9788898873..8dcd40be257 100644
--- a/src/renderers/shared/shared/event/SyntheticEvent.js
+++ b/src/renderers/shared/shared/event/SyntheticEvent.js
@@ -13,17 +13,14 @@
 
 'use strict';
 
-var emptyFunction = require('fbjs/lib/emptyFunction');
-var invariant = require('fbjs/lib/invariant');
+import emptyFunction from 'fbjs/lib/emptyFunction';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
 
 var didWarnForAddedNewProperty = false;
 var isProxySupported = typeof Proxy === 'function';
 var EVENT_POOL_SIZE = 10;
 
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
 var shouldBeReleasedProperties = [
   'dispatchConfig',
   '_targetInst',
@@ -71,7 +68,7 @@ var EventInterface = {
  * @param {object} nativeEvent Native browser event.
  * @param {DOMEventTarget} nativeEventTarget Target node.
  */
-function SyntheticEvent(
+export default function SyntheticEvent(
   dispatchConfig,
   targetInst,
   nativeEvent,
@@ -275,8 +272,6 @@ if (__DEV__) {
 
 addEventPoolingTo(SyntheticEvent);
 
-module.exports = SyntheticEvent;
-
 /**
   * Helper to nullify syntheticEvent instance properties when destructing
   *
diff --git a/src/renderers/shared/shared/event/eventPlugins/ResponderEventPlugin.js b/src/renderers/shared/shared/event/eventPlugins/ResponderEventPlugin.js
index 6fb3e4a6f0c..ad29d79ebb1 100644
--- a/src/renderers/shared/shared/event/eventPlugins/ResponderEventPlugin.js
+++ b/src/renderers/shared/shared/event/eventPlugins/ResponderEventPlugin.js
@@ -11,21 +11,24 @@
 
 'use strict';
 
-var EventPluginUtils = require('EventPluginUtils');
-var EventPropagators = require('EventPropagators');
-var ReactTreeTraversal = require('ReactTreeTraversal');
-var ResponderSyntheticEvent = require('ResponderSyntheticEvent');
-var ResponderTouchHistoryStore = require('ResponderTouchHistoryStore');
-
-var accumulate = require('accumulate');
-
-var isStartish = EventPluginUtils.isStartish;
-var isMoveish = EventPluginUtils.isMoveish;
-var isEndish = EventPluginUtils.isEndish;
-var executeDirectDispatch = EventPluginUtils.executeDirectDispatch;
-var hasDispatches = EventPluginUtils.hasDispatches;
-var executeDispatchesInOrderStopAtTrue =
-  EventPluginUtils.executeDispatchesInOrderStopAtTrue;
+import {
+  isStartish,
+  isMoveish,
+  isEndish,
+  executeDirectDispatch,
+  hasDispatches,
+  executeDispatchesInOrderStopAtTrue,
+  getInstanceFromNode,
+} from 'EventPluginUtils';
+import {
+  accumulateDirectDispatches,
+  accumulateTwoPhaseDispatches,
+  accumulateTwoPhaseDispatchesSkipTarget,
+} from 'EventPropagators';
+import {getLowestCommonAncestor, isAncestor} from 'ReactTreeTraversal';
+import ResponderSyntheticEvent from 'ResponderSyntheticEvent';
+import ResponderTouchHistoryStore from 'ResponderTouchHistoryStore';
+import accumulate from 'accumulate';
 
 /**
  * Instance of element that should respond to touch/move types of interactions,
@@ -331,7 +334,7 @@ function setResponderAndExtractTransfer(
   // TODO: stop one short of the current responder.
   var bubbleShouldSetFrom = !responderInst
     ? targetInst
-    : ReactTreeTraversal.getLowestCommonAncestor(responderInst, targetInst);
+    : getLowestCommonAncestor(responderInst, targetInst);
 
   // When capturing/bubbling the "shouldSet" event, we want to skip the target
   // (deepest ID) if it happens to be the current responder. The reasoning:
@@ -346,9 +349,9 @@ function setResponderAndExtractTransfer(
   );
   shouldSetEvent.touchHistory = ResponderTouchHistoryStore.touchHistory;
   if (skipOverBubbleShouldSetFrom) {
-    EventPropagators.accumulateTwoPhaseDispatchesSkipTarget(shouldSetEvent);
+    accumulateTwoPhaseDispatchesSkipTarget(shouldSetEvent);
   } else {
-    EventPropagators.accumulateTwoPhaseDispatches(shouldSetEvent);
+    accumulateTwoPhaseDispatches(shouldSetEvent);
   }
   var wantsResponderInst = executeDispatchesInOrderStopAtTrue(shouldSetEvent);
   if (!shouldSetEvent.isPersistent()) {
@@ -367,7 +370,7 @@ function setResponderAndExtractTransfer(
   );
   grantEvent.touchHistory = ResponderTouchHistoryStore.touchHistory;
 
-  EventPropagators.accumulateDirectDispatches(grantEvent);
+  accumulateDirectDispatches(grantEvent);
   var blockHostResponder = executeDirectDispatch(grantEvent) === true;
   if (responderInst) {
     var terminationRequestEvent = ResponderSyntheticEvent.getPooled(
@@ -378,7 +381,7 @@ function setResponderAndExtractTransfer(
     );
     terminationRequestEvent.touchHistory =
       ResponderTouchHistoryStore.touchHistory;
-    EventPropagators.accumulateDirectDispatches(terminationRequestEvent);
+    accumulateDirectDispatches(terminationRequestEvent);
     var shouldSwitch =
       !hasDispatches(terminationRequestEvent) ||
       executeDirectDispatch(terminationRequestEvent);
@@ -394,7 +397,7 @@ function setResponderAndExtractTransfer(
         nativeEventTarget,
       );
       terminateEvent.touchHistory = ResponderTouchHistoryStore.touchHistory;
-      EventPropagators.accumulateDirectDispatches(terminateEvent);
+      accumulateDirectDispatches(terminateEvent);
       extracted = accumulate(extracted, [grantEvent, terminateEvent]);
       changeResponder(wantsResponderInst, blockHostResponder);
     } else {
@@ -405,7 +408,7 @@ function setResponderAndExtractTransfer(
         nativeEventTarget,
       );
       rejectEvent.touchHistory = ResponderTouchHistoryStore.touchHistory;
-      EventPropagators.accumulateDirectDispatches(rejectEvent);
+      accumulateDirectDispatches(rejectEvent);
       extracted = accumulate(extracted, rejectEvent);
     }
   } else {
@@ -453,8 +456,8 @@ function noResponderTouches(nativeEvent) {
     var target = activeTouch.target;
     if (target !== null && target !== undefined && target !== 0) {
       // Is the original touch location inside of the current responder?
-      var targetInst = EventPluginUtils.getInstanceFromNode(target);
-      if (ReactTreeTraversal.isAncestor(responderInst, targetInst)) {
+      var targetInst = getInstanceFromNode(target);
+      if (isAncestor(responderInst, targetInst)) {
         return false;
       }
     }
@@ -531,7 +534,7 @@ var ResponderEventPlugin = {
         nativeEventTarget,
       );
       gesture.touchHistory = ResponderTouchHistoryStore.touchHistory;
-      EventPropagators.accumulateDirectDispatches(gesture);
+      accumulateDirectDispatches(gesture);
       extracted = accumulate(extracted, gesture);
     }
 
@@ -553,7 +556,7 @@ var ResponderEventPlugin = {
         nativeEventTarget,
       );
       finalEvent.touchHistory = ResponderTouchHistoryStore.touchHistory;
-      EventPropagators.accumulateDirectDispatches(finalEvent);
+      accumulateDirectDispatches(finalEvent);
       extracted = accumulate(extracted, finalEvent);
       changeResponder(null);
     }
@@ -596,4 +599,4 @@ var ResponderEventPlugin = {
   },
 };
 
-module.exports = ResponderEventPlugin;
+export default ResponderEventPlugin;
diff --git a/src/renderers/shared/shared/event/eventPlugins/ResponderSyntheticEvent.js b/src/renderers/shared/shared/event/eventPlugins/ResponderSyntheticEvent.js
index f8e2132d56a..c455056eea1 100644
--- a/src/renderers/shared/shared/event/eventPlugins/ResponderSyntheticEvent.js
+++ b/src/renderers/shared/shared/event/eventPlugins/ResponderSyntheticEvent.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var SyntheticEvent = require('SyntheticEvent');
+import SyntheticEvent from 'SyntheticEvent';
 
 /**
  * `touchHistory` isn't actually on the native event, but putting it in the
@@ -47,4 +47,4 @@ function ResponderSyntheticEvent(
 
 SyntheticEvent.augmentClass(ResponderSyntheticEvent, ResponderEventInterface);
 
-module.exports = ResponderSyntheticEvent;
+export default ResponderSyntheticEvent;
diff --git a/src/renderers/shared/shared/event/eventPlugins/ResponderTouchHistoryStore.js b/src/renderers/shared/shared/event/eventPlugins/ResponderTouchHistoryStore.js
index 6a7360c4216..e2fc066722b 100644
--- a/src/renderers/shared/shared/event/eventPlugins/ResponderTouchHistoryStore.js
+++ b/src/renderers/shared/shared/event/eventPlugins/ResponderTouchHistoryStore.js
@@ -12,15 +12,9 @@
 
 'use strict';
 
-const EventPluginUtils = require('EventPluginUtils');
-
-const invariant = require('fbjs/lib/invariant');
-
-const {isEndish, isMoveish, isStartish} = EventPluginUtils;
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
+import {isEndish, isMoveish, isStartish} from 'EventPluginUtils';
+import invariant from 'fbjs/lib/invariant';
+import warning from 'fbjs/lib/warning';
 
 /**
  * Tracks the position and time of each active touch by `touch.identifier`. We
@@ -222,4 +216,4 @@ const ResponderTouchHistoryStore = {
   touchHistory,
 };
 
-module.exports = ResponderTouchHistoryStore;
+export default ResponderTouchHistoryStore;
diff --git a/src/renderers/shared/shared/event/eventPlugins/TouchHistoryMath.js b/src/renderers/shared/shared/event/eventPlugins/TouchHistoryMath.js
index 50006f7e728..c56c7d529a2 100644
--- a/src/renderers/shared/shared/event/eventPlugins/TouchHistoryMath.js
+++ b/src/renderers/shared/shared/event/eventPlugins/TouchHistoryMath.js
@@ -145,4 +145,4 @@ var TouchHistoryMath = {
   noCentroid: -1,
 };
 
-module.exports = TouchHistoryMath;
+export default TouchHistoryMath;
diff --git a/src/renderers/shared/shared/event/eventPlugins/__tests__/ResponderEventPlugin-test.js b/src/renderers/shared/shared/event/eventPlugins/__tests__/ResponderEventPlugin-test.js
index 0810ce7d3a7..884561fa151 100644
--- a/src/renderers/shared/shared/event/eventPlugins/__tests__/ResponderEventPlugin-test.js
+++ b/src/renderers/shared/shared/event/eventPlugins/__tests__/ResponderEventPlugin-test.js
@@ -11,6 +11,8 @@
 
 'use strict';
 
+var {HostComponent} = require('ReactTypeOfWork');
+
 var EventPluginHub;
 var ResponderEventPlugin;
 
@@ -320,35 +322,37 @@ var PARENT_HOST_NODE = {};
 var CHILD_HOST_NODE = {};
 var CHILD_HOST_NODE2 = {};
 
+// These intentionally look like Fibers. ReactTreeTraversal depends on their field names.
+// TODO: we could test this with regular DOM nodes (and real fibers) instead.
 var GRANDPARENT_INST = {
-  _hostParent: null,
-  _rootNodeID: '1',
-  _hostNode: GRANDPARENT_HOST_NODE,
-  _currentElement: {props: {}},
+  return: null,
+  tag: HostComponent,
+  stateNode: GRANDPARENT_HOST_NODE,
+  memoizedProps: {},
 };
 var PARENT_INST = {
-  _hostParent: GRANDPARENT_INST,
-  _rootNodeID: '2',
-  _hostNode: PARENT_HOST_NODE,
-  _currentElement: {props: {}},
+  return: GRANDPARENT_INST,
+  tag: HostComponent,
+  stateNode: PARENT_HOST_NODE,
+  memoizedProps: {},
 };
 var CHILD_INST = {
-  _hostParent: PARENT_INST,
-  _rootNodeID: '3',
-  _hostNode: CHILD_HOST_NODE,
-  _currentElement: {props: {}},
+  return: PARENT_INST,
+  tag: HostComponent,
+  stateNode: CHILD_HOST_NODE,
+  memoizedProps: {},
 };
 var CHILD_INST2 = {
-  _hostParent: PARENT_INST,
-  _rootNodeID: '4',
-  _hostNode: CHILD_HOST_NODE2,
-  _currentElement: {props: {}},
+  return: PARENT_INST,
+  tag: HostComponent,
+  stateNode: CHILD_HOST_NODE2,
+  memoizedProps: {},
 };
 
-GRANDPARENT_HOST_NODE._reactInstance = GRANDPARENT_INST;
-PARENT_HOST_NODE._reactInstance = PARENT_INST;
-CHILD_HOST_NODE._reactInstance = CHILD_INST;
-CHILD_HOST_NODE2._reactInstance = CHILD_INST2;
+GRANDPARENT_HOST_NODE.testInstance = GRANDPARENT_INST;
+PARENT_HOST_NODE.testInstance = PARENT_INST;
+CHILD_HOST_NODE.testInstance = CHILD_INST;
+CHILD_HOST_NODE2.testInstance = CHILD_INST2;
 
 var three = {
   grandParent: GRANDPARENT_HOST_NODE,
@@ -363,19 +367,23 @@ var siblings = {
 };
 
 function getInstanceFromNode(node) {
-  return node._reactInstance;
+  return node.testInstance;
 }
 
 function getNodeFromInstance(inst) {
-  return inst._hostNode;
+  return inst.stateNode;
+}
+
+function getFiberCurrentPropsFromNode(node) {
+  return node.testInstance.memoizedProps;
 }
 
-function putListener(node, registrationName, handler) {
-  node._currentElement.props[registrationName] = handler;
+function putListener(instance, registrationName, handler) {
+  instance.memoizedProps[registrationName] = handler;
 }
 
-function deleteAllListeners(node) {
-  node._currentElement.props = {};
+function deleteAllListeners(instance) {
+  instance.memoizedProps = {};
 }
 
 describe('ResponderEventPlugin', () => {
@@ -400,6 +408,7 @@ describe('ResponderEventPlugin', () => {
     injectComponentTree({
       getInstanceFromNode,
       getNodeFromInstance,
+      getFiberCurrentPropsFromNode,
     });
   });
 
diff --git a/src/renderers/shared/shared/event/getVendorPrefixedEventName.js b/src/renderers/shared/shared/event/getVendorPrefixedEventName.js
index 7cbceff9fd5..fe3be8a32f4 100644
--- a/src/renderers/shared/shared/event/getVendorPrefixedEventName.js
+++ b/src/renderers/shared/shared/event/getVendorPrefixedEventName.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-var ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
+import ExecutionEnvironment from 'fbjs/lib/ExecutionEnvironment';
 
 /**
  * Generate a mapping of standard vendor prefixes using the defined style property and event name.
@@ -98,4 +98,4 @@ function getVendorPrefixedEventName(eventName) {
   return '';
 }
 
-module.exports = getVendorPrefixedEventName;
+export default getVendorPrefixedEventName;
diff --git a/src/renderers/shared/shared/getContextForSubtree.js b/src/renderers/shared/shared/getContextForSubtree.js
deleted file mode 100644
index 2883e36834d..00000000000
--- a/src/renderers/shared/shared/getContextForSubtree.js
+++ /dev/null
@@ -1,41 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule getContextForSubtree
- * @flow
- */
-
-const ReactInstanceMap = require('ReactInstanceMap');
-
-const emptyObject = require('fbjs/lib/emptyObject');
-const invariant = require('fbjs/lib/invariant');
-
-let getContextFiber = function(arg) {
-  invariant(false, 'Missing injection for fiber getContextForSubtree');
-};
-
-function getContextForSubtree(
-  parentComponent: ?ReactComponent<any, any, any>,
-): Object {
-  if (!parentComponent) {
-    return emptyObject;
-  }
-
-  const instance = ReactInstanceMap.get(parentComponent);
-  if (typeof instance.tag === 'number') {
-    return getContextFiber(instance);
-  } else {
-    return instance._processChildContext(instance._context);
-  }
-}
-
-getContextForSubtree._injectFiber = function(fn) {
-  getContextFiber = fn;
-};
-
-module.exports = getContextForSubtree;
diff --git a/src/renderers/shared/shared/shouldUpdateReactComponent.js b/src/renderers/shared/shared/shouldUpdateReactComponent.js
deleted file mode 100644
index 097eab1c542..00000000000
--- a/src/renderers/shared/shared/shouldUpdateReactComponent.js
+++ /dev/null
@@ -1,45 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule shouldUpdateReactComponent
- */
-
-'use strict';
-
-/**
- * Given a `prevElement` and `nextElement`, determines if the existing
- * instance should be updated as opposed to being destroyed or replaced by a new
- * instance. Both arguments are elements. This ensures that this logic can
- * operate on stateless trees without any backing instance.
- *
- * @param {?object} prevElement
- * @param {?object} nextElement
- * @return {boolean} True if the existing instance should be updated.
- * @protected
- */
-function shouldUpdateReactComponent(prevElement, nextElement) {
-  var prevEmpty = prevElement === null || prevElement === false;
-  var nextEmpty = nextElement === null || nextElement === false;
-  if (prevEmpty || nextEmpty) {
-    return prevEmpty === nextEmpty;
-  }
-
-  var prevType = typeof prevElement;
-  var nextType = typeof nextElement;
-  if (prevType === 'string' || prevType === 'number') {
-    return nextType === 'string' || nextType === 'number';
-  } else {
-    return (
-      nextType === 'object' &&
-      prevElement.type === nextElement.type &&
-      prevElement.key === nextElement.key
-    );
-  }
-}
-
-module.exports = shouldUpdateReactComponent;
diff --git a/src/renderers/shared/stack/reconciler/CallbackQueue.js b/src/renderers/shared/stack/reconciler/CallbackQueue.js
deleted file mode 100644
index ea10bb4be40..00000000000
--- a/src/renderers/shared/stack/reconciler/CallbackQueue.js
+++ /dev/null
@@ -1,108 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule CallbackQueue
- * @flow
- */
-
-'use strict';
-
-var PooledClass = require('PooledClass');
-
-var invariant = require('fbjs/lib/invariant');
-var validateCallback = require('validateCallback');
-
-/**
- * A specialized pseudo-event module to help keep track of components waiting to
- * be notified when their DOM representations are available for use.
- *
- * This implements `PooledClass`, so you should never need to instantiate this.
- * Instead, use `CallbackQueue.getPooled()`.
- *
- * @class CallbackQueue
- * @implements PooledClass
- * @internal
- */
-class CallbackQueue<T> {
-  _callbacks: ?Array<() => void>;
-  _contexts: ?Array<T>;
-
-  constructor() {
-    this._callbacks = null;
-    this._contexts = null;
-  }
-
-  /**
-   * Enqueues a callback to be invoked when `notifyAll` is invoked.
-   *
-   * @param {function} callback Invoked when `notifyAll` is invoked.
-   * @param {?object} context Context to call `callback` with.
-   * @internal
-   */
-  enqueue(callback: () => void, context: T) {
-    this._callbacks = this._callbacks || [];
-    this._callbacks.push(callback);
-    this._contexts = this._contexts || [];
-    this._contexts.push(context);
-  }
-
-  /**
-   * Invokes all enqueued callbacks and clears the queue. This is invoked after
-   * the DOM representation of a component has been created or updated.
-   *
-   * @internal
-   */
-  notifyAll() {
-    var callbacks = this._callbacks;
-    var contexts = this._contexts;
-    if (callbacks && contexts) {
-      invariant(
-        callbacks.length === contexts.length,
-        'Mismatched list of contexts in callback queue',
-      );
-      this._callbacks = null;
-      this._contexts = null;
-      for (var i = 0; i < callbacks.length; i++) {
-        validateCallback(callbacks[i]);
-        callbacks[i].call(contexts[i]);
-      }
-      callbacks.length = 0;
-      contexts.length = 0;
-    }
-  }
-
-  checkpoint() {
-    return this._callbacks ? this._callbacks.length : 0;
-  }
-
-  rollback(len: number) {
-    if (this._callbacks && this._contexts) {
-      this._callbacks.length = len;
-      this._contexts.length = len;
-    }
-  }
-
-  /**
-   * Resets the internal queue.
-   *
-   * @internal
-   */
-  reset() {
-    this._callbacks = null;
-    this._contexts = null;
-  }
-
-  /**
-   * `PooledClass` looks for this.
-   */
-  destructor() {
-    this.reset();
-  }
-}
-
-module.exports = PooledClass.addPoolingTo(CallbackQueue);
diff --git a/src/renderers/shared/stack/reconciler/KeyEscapeUtils.js b/src/renderers/shared/stack/reconciler/KeyEscapeUtils.js
deleted file mode 100644
index 184138bc672..00000000000
--- a/src/renderers/shared/stack/reconciler/KeyEscapeUtils.js
+++ /dev/null
@@ -1,65 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule KeyEscapeUtils
- * @flow
- */
-
-'use strict';
-
-var emptyFunction = require('fbjs/lib/emptyFunction');
-
-/**
- * Escape and wrap key so it is safe to use as a reactid
- *
- * @param {string} key to be escaped.
- * @return {string} the escaped key.
- */
-function escape(key: string): string {
-  var escapeRegex = /[=:]/g;
-  var escaperLookup = {
-    '=': '=0',
-    ':': '=2',
-  };
-  var escapedString = ('' + key).replace(escapeRegex, function(match) {
-    return escaperLookup[match];
-  });
-
-  return '$' + escapedString;
-}
-
-var unescapeInDev = emptyFunction;
-if (__DEV__) {
-  /**
-   * Unescape and unwrap key for human-readable display
-   *
-   * @param {string} key to unescape.
-   * @return {string} the unescaped key.
-   */
-  unescapeInDev = function(key: string): string {
-    var unescapeRegex = /(=0|=2)/g;
-    var unescaperLookup = {
-      '=0': '=',
-      '=2': ':',
-    };
-    var keySubstring = key[0] === '.' && key[1] === '$'
-      ? key.substring(2)
-      : key.substring(1);
-
-    return ('' + keySubstring).replace(unescapeRegex, function(match) {
-      return unescaperLookup[match];
-    });
-  };
-}
-
-var KeyEscapeUtils = {
-  escape: escape,
-  unescapeInDev: unescapeInDev,
-};
-
-module.exports = KeyEscapeUtils;
diff --git a/src/renderers/shared/stack/reconciler/ReactChildReconciler.js b/src/renderers/shared/stack/reconciler/ReactChildReconciler.js
deleted file mode 100644
index 0f6d7dfd4af..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactChildReconciler.js
+++ /dev/null
@@ -1,214 +0,0 @@
-/**
- * Copyright 2014-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactChildReconciler
- */
-
-'use strict';
-
-var KeyEscapeUtils = require('KeyEscapeUtils');
-var ReactReconciler = require('ReactReconciler');
-
-var instantiateReactComponent = require('instantiateReactComponent');
-var shouldUpdateReactComponent = require('shouldUpdateReactComponent');
-var traverseStackChildren = require('traverseStackChildren');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
-var ReactComponentTreeHook;
-
-if (
-  typeof process !== 'undefined' &&
-  process.env &&
-  process.env.NODE_ENV === 'test'
-) {
-  // Temporary hack.
-  // Inline requires don't work well with Jest:
-  // https://github.com/facebook/react/issues/7240
-  // Remove the inline requires when we don't need them anymore:
-  // https://github.com/facebook/react/pull/7178
-  ReactComponentTreeHook = require('ReactGlobalSharedState')
-    .ReactComponentTreeHook;
-}
-
-function instantiateChild(childInstances, child, name, selfDebugID) {
-  // We found a component instance.
-  var keyUnique = childInstances[name] === undefined;
-  if (__DEV__) {
-    if (!ReactComponentTreeHook) {
-      ReactComponentTreeHook = require('ReactGlobalSharedState')
-        .ReactComponentTreeHook;
-    }
-    if (!keyUnique) {
-      warning(
-        false,
-        'flattenChildren(...): ' +
-          'Encountered two children with the same key, `%s`. ' +
-          'Keys should be unique so that components maintain their identity ' +
-          'across updates. Non-unique keys may cause children to be ' +
-          'duplicated and/or omitted — the behavior is unsupported and ' +
-          'could change in a future version.%s',
-        KeyEscapeUtils.unescapeInDev(name),
-        ReactComponentTreeHook.getStackAddendumByID(selfDebugID),
-      );
-    }
-  }
-  if (child != null && keyUnique) {
-    childInstances[name] = instantiateReactComponent(child, true);
-  }
-}
-
-/**
- * ReactChildReconciler provides helpers for initializing or updating a set of
- * children. Its output is suitable for passing it onto ReactMultiChild which
- * does diffed reordering and insertion.
- */
-var ReactChildReconciler = {
-  /**
-   * Generates a "mount image" for each of the supplied children. In the case
-   * of `ReactDOMComponent`, a mount image is a string of markup.
-   *
-   * @param {?object} nestedChildNodes Nested child maps.
-   * @return {?object} A set of child instances.
-   * @internal
-   */
-  instantiateChildren: function(
-    nestedChildNodes,
-    transaction,
-    context,
-    selfDebugID, // 0 in production and for roots
-  ) {
-    if (nestedChildNodes == null) {
-      return null;
-    }
-    var childInstances = {};
-
-    if (__DEV__) {
-      traverseStackChildren(
-        nestedChildNodes,
-        (childInsts, child, name) =>
-          instantiateChild(childInsts, child, name, selfDebugID),
-        childInstances,
-      );
-    } else {
-      traverseStackChildren(nestedChildNodes, instantiateChild, childInstances);
-    }
-    return childInstances;
-  },
-
-  /**
-   * Updates the rendered children and returns a new set of children.
-   *
-   * @param {?object} prevChildren Previously initialized set of children.
-   * @param {?object} nextChildren Flat child element maps.
-   * @param {ReactReconcileTransaction} transaction
-   * @param {object} context
-   * @return {?object} A new set of child instances.
-   * @internal
-   */
-  updateChildren: function(
-    prevChildren,
-    nextChildren,
-    mountImages,
-    removedNodes,
-    transaction,
-    hostParent,
-    hostContainerInfo,
-    context,
-    selfDebugID, // 0 in production and for roots
-  ) {
-    // We currently don't have a way to track moves here but if we use iterators
-    // instead of for..in we can zip the iterators and check if an item has
-    // moved.
-    // TODO: If nothing has changed, return the prevChildren object so that we
-    // can quickly bailout if nothing has changed.
-    if (!nextChildren && !prevChildren) {
-      return;
-    }
-    var name;
-    var prevChild;
-    for (name in nextChildren) {
-      if (!nextChildren.hasOwnProperty(name)) {
-        continue;
-      }
-      prevChild = prevChildren && prevChildren[name];
-      var prevElement = prevChild && prevChild._currentElement;
-      var nextElement = nextChildren[name];
-      if (
-        prevChild != null &&
-        shouldUpdateReactComponent(prevElement, nextElement)
-      ) {
-        ReactReconciler.receiveComponent(
-          prevChild,
-          nextElement,
-          transaction,
-          context,
-        );
-        nextChildren[name] = prevChild;
-      } else {
-        // The child must be instantiated before it's mounted.
-        var nextChildInstance = instantiateReactComponent(nextElement, true);
-        nextChildren[name] = nextChildInstance;
-        // Creating mount image now ensures refs are resolved in right order
-        // (see https://github.com/facebook/react/pull/7101 for explanation).
-        var nextChildMountImage = ReactReconciler.mountComponent(
-          nextChildInstance,
-          transaction,
-          hostParent,
-          hostContainerInfo,
-          context,
-          selfDebugID,
-        );
-        mountImages.push(nextChildMountImage);
-        if (prevChild) {
-          removedNodes[name] = ReactReconciler.getHostNode(prevChild);
-          ReactReconciler.unmountComponent(
-            prevChild,
-            false /* safely */,
-            false /* skipLifecycle */,
-          );
-        }
-      }
-    }
-    // Unmount children that are no longer present.
-    for (name in prevChildren) {
-      if (
-        prevChildren.hasOwnProperty(name) &&
-        !(nextChildren && nextChildren.hasOwnProperty(name))
-      ) {
-        prevChild = prevChildren[name];
-        removedNodes[name] = ReactReconciler.getHostNode(prevChild);
-        ReactReconciler.unmountComponent(
-          prevChild,
-          false /* safely */,
-          false /* skipLifecycle */,
-        );
-      }
-    }
-  },
-
-  /**
-   * Unmounts all rendered children. This should be used to clean up children
-   * when this component is unmounted.
-   *
-   * @param {?object} renderedChildren Previously initialized set of children.
-   * @internal
-   */
-  unmountChildren: function(renderedChildren, safely, skipLifecycle) {
-    for (var name in renderedChildren) {
-      if (renderedChildren.hasOwnProperty(name)) {
-        var renderedChild = renderedChildren[name];
-        ReactReconciler.unmountComponent(renderedChild, safely, skipLifecycle);
-      }
-    }
-  },
-};
-
-module.exports = ReactChildReconciler;
diff --git a/src/renderers/shared/stack/reconciler/ReactComponentEnvironment.js b/src/renderers/shared/stack/reconciler/ReactComponentEnvironment.js
deleted file mode 100644
index 25e4b9c5d09..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactComponentEnvironment.js
+++ /dev/null
@@ -1,55 +0,0 @@
-/**
- * Copyright 2014-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactComponentEnvironment
- * @flow
- */
-
-'use strict';
-
-var invariant = require('fbjs/lib/invariant');
-
-type ReplaceNodeWithMarkup = (node: HTMLElement, markup: string) => void;
-type ProcessChildrenUpdates = (instance: mixed, updates: mixed) => void;
-
-type Environment = {
-  replaceNodeWithMarkup: ReplaceNodeWithMarkup,
-  processChildrenUpdates: ProcessChildrenUpdates,
-};
-
-var injected = false;
-
-var ReactComponentEnvironment = {
-  /**
-   * Optionally injectable hook for swapping out mount images in the middle of
-   * the tree.
-   */
-  replaceNodeWithMarkup: (null: ?ReplaceNodeWithMarkup),
-
-  /**
-   * Optionally injectable hook for processing a queue of child updates. Will
-   * later move into MultiChildComponents.
-   */
-  processChildrenUpdates: (null: ?ReplaceNodeWithMarkup),
-
-  injection: {
-    injectEnvironment: function(environment: Environment) {
-      invariant(
-        !injected,
-        'ReactCompositeComponent: injectEnvironment() can only be called once.',
-      );
-      ReactComponentEnvironment.replaceNodeWithMarkup =
-        environment.replaceNodeWithMarkup;
-      ReactComponentEnvironment.processChildrenUpdates =
-        environment.processChildrenUpdates;
-      injected = true;
-    },
-  },
-};
-
-module.exports = ReactComponentEnvironment;
diff --git a/src/renderers/shared/stack/reconciler/ReactCompositeComponent.js b/src/renderers/shared/stack/reconciler/ReactCompositeComponent.js
deleted file mode 100644
index 52a4b08c888..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactCompositeComponent.js
+++ /dev/null
@@ -1,1349 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactCompositeComponent
- */
-
-'use strict';
-
-var React = require('react');
-var ReactComponentEnvironment = require('ReactComponentEnvironment');
-var ReactCompositeComponentTypes = require('ReactCompositeComponentTypes');
-var ReactErrorUtils = require('ReactErrorUtils');
-var ReactInstanceMap = require('ReactInstanceMap');
-var ReactInstrumentation = require('ReactInstrumentation');
-var ReactNodeTypes = require('ReactNodeTypes');
-var ReactReconciler = require('ReactReconciler');
-var {ReactCurrentOwner} = require('ReactGlobalSharedState');
-
-if (__DEV__) {
-  var {ReactDebugCurrentFrame} = require('ReactGlobalSharedState');
-  var ReactDebugCurrentStack = require('ReactDebugCurrentStack');
-  var warning = require('fbjs/lib/warning');
-  var warningAboutMissingGetChildContext = {};
-}
-
-var checkPropTypes = require('prop-types/checkPropTypes');
-var emptyObject = require('fbjs/lib/emptyObject');
-var invariant = require('fbjs/lib/invariant');
-var shallowEqual = require('fbjs/lib/shallowEqual');
-var shouldUpdateReactComponent = require('shouldUpdateReactComponent');
-
-function StatelessComponent(Component) {}
-StatelessComponent.prototype.render = function() {
-  var Component = ReactInstanceMap.get(this)._currentElement.type;
-  var element = Component(this.props, this.context, this.updater);
-  return element;
-};
-
-function shouldConstruct(Component) {
-  return !!(Component.prototype && Component.prototype.isReactComponent);
-}
-
-function isPureComponent(Component) {
-  return !!(Component.prototype && Component.prototype.isPureReactComponent);
-}
-
-// Separated into a function to contain deoptimizations caused by try/finally.
-function measureLifeCyclePerf(fn, debugID, timerType) {
-  if (debugID === 0) {
-    // Top-level wrappers (see ReactMount) and empty components (see
-    // ReactDOMEmptyComponent) are invisible to hooks and devtools.
-    // Both are implementation details that should go away in the future.
-    return fn();
-  }
-
-  ReactInstrumentation.debugTool.onBeginLifeCycleTimer(debugID, timerType);
-  try {
-    return fn();
-  } finally {
-    ReactInstrumentation.debugTool.onEndLifeCycleTimer(debugID, timerType);
-  }
-}
-
-/**
- * ------------------ The Life-Cycle of a Composite Component ------------------
- *
- * - constructor: Initialization of state. The instance is now retained.
- *   - componentWillMount
- *   - render
- *   - [children's constructors]
- *     - [children's componentWillMount and render]
- *     - [children's componentDidMount]
- *     - componentDidMount
- *
- *       Update Phases:
- *       - componentWillReceiveProps (only called if parent updated)
- *       - shouldComponentUpdate
- *         - componentWillUpdate
- *           - render
- *           - [children's constructors or receive props phases]
- *         - componentDidUpdate
- *
- *     - componentWillUnmount
- *     - [children's componentWillUnmount]
- *   - [children destroyed]
- * - (destroyed): The instance is now blank, released by React and ready for GC.
- *
- * -----------------------------------------------------------------------------
- */
-
-/**
- * An incrementing ID assigned to each component when it is mounted. This is
- * used to enforce the order in which `ReactUpdates` updates dirty components.
- *
- * @private
- */
-var nextMountID = 1;
-
-/**
- * @lends {ReactCompositeComponent.prototype}
- */
-var ReactCompositeComponent = {
-  /**
-   * Base constructor for all composite component.
-   *
-   * @param {ReactElement} element
-   * @final
-   * @internal
-   */
-  construct: function(element) {
-    this._currentElement = element;
-    this._rootNodeID = 0;
-    this._compositeType = null;
-    this._instance = null;
-    this._hostParent = null;
-    this._hostContainerInfo = null;
-
-    // See ReactUpdateQueue
-    this._updateBatchNumber = null;
-    this._pendingElement = null;
-    this._pendingStateQueue = null;
-    this._pendingReplaceState = false;
-    this._pendingForceUpdate = false;
-
-    this._renderedNodeType = null;
-    this._renderedComponent = null;
-    this._context = null;
-    this._mountOrder = 0;
-    this._topLevelWrapper = null;
-
-    // See ReactUpdates and ReactUpdateQueue.
-    this._pendingCallbacks = null;
-
-    // ComponentWillUnmount shall only be called once
-    this._calledComponentWillUnmount = false;
-
-    if (__DEV__) {
-      this._warnedAboutRefsInRender = false;
-    }
-  },
-
-  /**
-   * Initializes the component, renders markup, and registers event listeners.
-   *
-   * @param {ReactReconcileTransaction|ReactServerRenderingTransaction} transaction
-   * @param {?object} hostParent
-   * @param {?object} hostContainerInfo
-   * @param {?object} context
-   * @return {?string} Rendered markup to be inserted into the DOM.
-   * @final
-   * @internal
-   */
-  mountComponent: function(
-    transaction,
-    hostParent,
-    hostContainerInfo,
-    context,
-  ) {
-    this._context = context;
-    this._mountOrder = nextMountID++;
-    this._hostParent = hostParent;
-    this._hostContainerInfo = hostContainerInfo;
-
-    var publicProps = this._currentElement.props;
-    var publicContext = this._processContext(context);
-
-    var Component = this._currentElement.type;
-
-    var updateQueue = transaction.getUpdateQueue();
-
-    // Initialize the public class
-    var doConstruct = shouldConstruct(Component);
-    var inst = this._constructComponent(
-      doConstruct,
-      publicProps,
-      publicContext,
-      updateQueue,
-    );
-    var renderedElement;
-
-    // Support functional components
-    if (!doConstruct && (inst == null || inst.render == null)) {
-      renderedElement = inst;
-      if (__DEV__) {
-        warning(
-          !Component.childContextTypes,
-          '%s(...): childContextTypes cannot be defined on a functional component.',
-          Component.displayName || Component.name || 'Component',
-        );
-      }
-      invariant(
-        inst === null || inst === false || React.isValidElement(inst),
-        '%s(...): A valid React element (or null) must be returned. You may have ' +
-          'returned undefined, an array or some other invalid object.',
-        Component.displayName || Component.name || 'Component',
-      );
-      inst = new StatelessComponent(Component);
-      this._compositeType = ReactCompositeComponentTypes.StatelessFunctional;
-    } else {
-      if (isPureComponent(Component)) {
-        this._compositeType = ReactCompositeComponentTypes.PureClass;
-      } else {
-        this._compositeType = ReactCompositeComponentTypes.ImpureClass;
-      }
-    }
-
-    if (__DEV__) {
-      // This will throw later in _renderValidatedComponent, but add an early
-      // warning now to help debugging
-      if (inst.render == null) {
-        warning(
-          false,
-          '%s(...): No `render` method found on the returned component ' +
-            'instance: you may have forgotten to define `render`.',
-          Component.displayName || Component.name || 'Component',
-        );
-      }
-
-      var propsMutated = inst.props !== publicProps;
-      var componentName =
-        Component.displayName || Component.name || 'Component';
-
-      warning(
-        inst.props === undefined || !propsMutated,
-        '%s(...): When calling super() in `%s`, make sure to pass ' +
-          "up the same props that your component's constructor was passed.",
-        componentName,
-        componentName,
-      );
-    }
-
-    // These should be set up in the constructor, but as a convenience for
-    // simpler class abstractions, we set them up after the fact.
-    inst.props = publicProps;
-    inst.context = publicContext;
-    inst.refs = emptyObject;
-    inst.updater = updateQueue;
-
-    this._instance = inst;
-
-    // Store a reference from the instance back to the internal representation
-    ReactInstanceMap.set(inst, this);
-
-    if (__DEV__) {
-      // Since plain JS classes are defined without any special initialization
-      // logic, we can not catch common errors early. Therefore, we have to
-      // catch them here, at initialization time, instead.
-      warning(
-        !inst.getInitialState ||
-          inst.getInitialState.isReactClassApproved ||
-          inst.state,
-        'getInitialState was defined on %s, a plain JavaScript class. ' +
-          'This is only supported for classes created using React.createClass. ' +
-          'Did you mean to define a state property instead?',
-        this.getName() || 'a component',
-      );
-      warning(
-        !inst.getDefaultProps || inst.getDefaultProps.isReactClassApproved,
-        'getDefaultProps was defined on %s, a plain JavaScript class. ' +
-          'This is only supported for classes created using React.createClass. ' +
-          'Use a static property to define defaultProps instead.',
-        this.getName() || 'a component',
-      );
-      warning(
-        !inst.propTypes,
-        'propTypes was defined as an instance property on %s. Use a static ' +
-          'property to define propTypes instead.',
-        this.getName() || 'a component',
-      );
-      warning(
-        !inst.contextTypes,
-        'contextTypes was defined as an instance property on %s. Use a ' +
-          'static property to define contextTypes instead.',
-        this.getName() || 'a component',
-      );
-      warning(
-        typeof inst.componentShouldUpdate !== 'function',
-        '%s has a method called ' +
-          'componentShouldUpdate(). Did you mean shouldComponentUpdate()? ' +
-          'The name is phrased as a question because the function is ' +
-          'expected to return a value.',
-        this.getName() || 'A component',
-      );
-      warning(
-        typeof inst.componentDidUnmount !== 'function',
-        '%s has a method called ' +
-          'componentDidUnmount(). But there is no such lifecycle method. ' +
-          'Did you mean componentWillUnmount()?',
-        this.getName() || 'A component',
-      );
-      warning(
-        typeof inst.componentWillRecieveProps !== 'function',
-        '%s has a method called ' +
-          'componentWillRecieveProps(). Did you mean componentWillReceiveProps()?',
-        this.getName() || 'A component',
-      );
-      if (
-        isPureComponent(Component) &&
-        typeof inst.shouldComponentUpdate !== 'undefined'
-      ) {
-        warning(
-          false,
-          '%s has a method called shouldComponentUpdate(). ' +
-            'shouldComponentUpdate should not be used when extending React.PureComponent. ' +
-            'Please extend React.Component if shouldComponentUpdate is used.',
-          this.getName() || 'A pure component',
-        );
-      }
-      warning(
-        !inst.defaultProps,
-        'Setting defaultProps as an instance property on %s is not supported and will be ignored.' +
-          ' Instead, define defaultProps as a static property on %s.',
-        this.getName() || 'a component',
-        this.getName() || 'a component',
-      );
-    }
-
-    var initialState = inst.state;
-    if (initialState === undefined) {
-      inst.state = initialState = null;
-    }
-    invariant(
-      typeof initialState === 'object' && !Array.isArray(initialState),
-      '%s.state: must be set to an object or null',
-      this.getName() || 'ReactCompositeComponent',
-    );
-
-    this._pendingStateQueue = null;
-    this._pendingReplaceState = false;
-    this._pendingForceUpdate = false;
-
-    if (inst.componentWillMount) {
-      if (__DEV__) {
-        measureLifeCyclePerf(
-          () => inst.componentWillMount(),
-          this._debugID,
-          'componentWillMount',
-        );
-      } else {
-        inst.componentWillMount();
-      }
-      // When mounting, calls to `setState` by `componentWillMount` will set
-      // `this._pendingStateQueue` without triggering a re-render.
-      if (this._pendingStateQueue) {
-        inst.state = this._processPendingState(inst.props, inst.context);
-      }
-    }
-
-    var markup;
-    if (inst.componentDidCatch) {
-      markup = this.performInitialMountWithErrorHandling(
-        renderedElement,
-        hostParent,
-        hostContainerInfo,
-        transaction,
-        context,
-      );
-    } else {
-      markup = this.performInitialMount(
-        renderedElement,
-        hostParent,
-        hostContainerInfo,
-        transaction,
-        context,
-      );
-    }
-
-    if (inst.componentDidMount) {
-      if (__DEV__) {
-        transaction.getReactMountReady().enqueue(() => {
-          measureLifeCyclePerf(
-            () => inst.componentDidMount(),
-            this._debugID,
-            'componentDidMount',
-          );
-        });
-      } else {
-        transaction.getReactMountReady().enqueue(inst.componentDidMount, inst);
-      }
-    }
-
-    // setState callbacks during willMount should end up here
-    const callbacks = this._pendingCallbacks;
-    if (callbacks) {
-      this._pendingCallbacks = null;
-      for (let i = 0; i < callbacks.length; i++) {
-        transaction.getReactMountReady().enqueue(callbacks[i], inst);
-      }
-    }
-
-    return markup;
-  },
-
-  _constructComponent: function(
-    doConstruct,
-    publicProps,
-    publicContext,
-    updateQueue,
-  ) {
-    if (__DEV__ && !doConstruct) {
-      ReactCurrentOwner.current = this;
-      ReactDebugCurrentFrame.getCurrentStack =
-        ReactDebugCurrentStack.getStackAddendum;
-      try {
-        return this._constructComponentWithoutOwner(
-          doConstruct,
-          publicProps,
-          publicContext,
-          updateQueue,
-        );
-      } finally {
-        ReactCurrentOwner.current = null;
-        ReactDebugCurrentFrame.getCurrentStack = null;
-      }
-    } else {
-      return this._constructComponentWithoutOwner(
-        doConstruct,
-        publicProps,
-        publicContext,
-        updateQueue,
-      );
-    }
-  },
-
-  _constructComponentWithoutOwner: function(
-    doConstruct,
-    publicProps,
-    publicContext,
-    updateQueue,
-  ) {
-    var Component = this._currentElement.type;
-
-    if (doConstruct) {
-      if (__DEV__) {
-        return measureLifeCyclePerf(
-          () => new Component(publicProps, publicContext, updateQueue),
-          this._debugID,
-          'ctor',
-        );
-      } else {
-        return new Component(publicProps, publicContext, updateQueue);
-      }
-    }
-
-    // This can still be an instance in case of factory components
-    // but we'll count this as time spent rendering as the more common case.
-    if (__DEV__) {
-      return measureLifeCyclePerf(
-        () => Component(publicProps, publicContext, updateQueue),
-        this._debugID,
-        'render',
-      );
-    } else {
-      return Component(publicProps, publicContext, updateQueue);
-    }
-  },
-
-  performInitialMountWithErrorHandling: function(
-    renderedElement,
-    hostParent,
-    hostContainerInfo,
-    transaction,
-    context,
-  ) {
-    var markup;
-    var checkpoint = transaction.checkpoint();
-    try {
-      markup = this.performInitialMount(
-        renderedElement,
-        hostParent,
-        hostContainerInfo,
-        transaction,
-        context,
-      );
-    } catch (e) {
-      // Roll back to checkpoint, handle error (which may add items to the transaction), and take a new checkpoint
-      transaction.rollback(checkpoint);
-      this._instance.componentDidCatch(e);
-      if (this._pendingStateQueue) {
-        this._instance.state = this._processPendingState(
-          this._instance.props,
-          this._instance.context,
-        );
-      }
-      checkpoint = transaction.checkpoint();
-      this._renderedComponent.unmountComponent(
-        true /* safely */,
-        // Don't call componentWillUnmount() because they never fully mounted:
-        true /* skipLifecyle */,
-      );
-      transaction.rollback(checkpoint);
-
-      // Try again - we've informed the component about the error, so they can render an error message this time.
-      // If this throws again, the error will bubble up (and can be caught by a higher error boundary).
-      markup = this.performInitialMount(
-        renderedElement,
-        hostParent,
-        hostContainerInfo,
-        transaction,
-        context,
-      );
-    }
-    return markup;
-  },
-
-  performInitialMount: function(
-    renderedElement,
-    hostParent,
-    hostContainerInfo,
-    transaction,
-    context,
-  ) {
-    // If not a stateless component, we now render
-    if (renderedElement === undefined) {
-      renderedElement = this._renderValidatedComponent();
-    }
-
-    var nodeType = ReactNodeTypes.getType(renderedElement);
-    this._renderedNodeType = nodeType;
-    var child = this._instantiateReactComponent(
-      renderedElement,
-      nodeType !== ReactNodeTypes.EMPTY /* shouldHaveDebugID */,
-    );
-    this._renderedComponent = child;
-
-    var debugID = 0;
-    if (__DEV__) {
-      debugID = this._debugID;
-    }
-
-    var markup = ReactReconciler.mountComponent(
-      child,
-      transaction,
-      hostParent,
-      hostContainerInfo,
-      this._processChildContext(context),
-      debugID,
-    );
-
-    if (__DEV__) {
-      if (debugID !== 0) {
-        var childDebugIDs = child._debugID !== 0 ? [child._debugID] : [];
-        ReactInstrumentation.debugTool.onSetChildren(debugID, childDebugIDs);
-      }
-    }
-
-    return markup;
-  },
-
-  getHostNode: function() {
-    return ReactReconciler.getHostNode(this._renderedComponent);
-  },
-
-  /**
-   * Releases any resources allocated by `mountComponent`.
-   *
-   * @final
-   * @internal
-   */
-  unmountComponent: function(safely, skipLifecycle) {
-    if (!this._renderedComponent) {
-      return;
-    }
-
-    var inst = this._instance;
-
-    if (inst.componentWillUnmount && !inst._calledComponentWillUnmount) {
-      inst._calledComponentWillUnmount = true;
-
-      if (safely) {
-        if (!skipLifecycle) {
-          var name = this.getName() + '.componentWillUnmount()';
-          ReactErrorUtils.invokeGuardedCallbackAndCatchFirstError(
-            name,
-            inst.componentWillUnmount,
-            inst,
-          );
-        }
-      } else {
-        if (__DEV__) {
-          measureLifeCyclePerf(
-            () => inst.componentWillUnmount(),
-            this._debugID,
-            'componentWillUnmount',
-          );
-        } else {
-          inst.componentWillUnmount();
-        }
-      }
-    }
-
-    if (this._renderedComponent) {
-      ReactReconciler.unmountComponent(
-        this._renderedComponent,
-        safely,
-        skipLifecycle,
-      );
-      this._renderedNodeType = null;
-      this._renderedComponent = null;
-      this._instance = null;
-    }
-
-    // Reset pending fields
-    // Even if this component is scheduled for another update in ReactUpdates,
-    // it would still be ignored because these fields are reset.
-    this._pendingStateQueue = null;
-    this._pendingReplaceState = false;
-    this._pendingForceUpdate = false;
-    this._pendingCallbacks = null;
-    this._pendingElement = null;
-
-    // These fields do not really need to be reset since this object is no
-    // longer accessible.
-    this._context = null;
-    this._rootNodeID = 0;
-    this._topLevelWrapper = null;
-
-    // Delete the reference from the instance to this internal representation
-    // which allow the internals to be properly cleaned up even if the user
-    // leaks a reference to the public instance.
-    ReactInstanceMap.remove(inst);
-
-    // Some existing components rely on inst.props even after they've been
-    // destroyed (in event handlers).
-    // TODO: inst.props = null;
-    // TODO: inst.state = null;
-    // TODO: inst.context = null;
-  },
-
-  /**
-   * Filters the context object to only contain keys specified in
-   * `contextTypes`
-   *
-   * @param {object} context
-   * @return {?object}
-   * @private
-   */
-  _maskContext: function(context) {
-    var Component = this._currentElement.type;
-    var contextTypes = Component.contextTypes;
-    if (!contextTypes) {
-      return emptyObject;
-    }
-    var maskedContext = {};
-    for (var contextName in contextTypes) {
-      maskedContext[contextName] = context[contextName];
-    }
-    return maskedContext;
-  },
-
-  /**
-   * Filters the context object to only contain keys specified in
-   * `contextTypes`, and asserts that they are valid.
-   *
-   * @param {object} context
-   * @return {?object}
-   * @private
-   */
-  _processContext: function(context) {
-    var maskedContext = this._maskContext(context);
-    if (__DEV__) {
-      var Component = this._currentElement.type;
-      if (Component.contextTypes) {
-        this._checkContextTypes(
-          Component.contextTypes,
-          maskedContext,
-          'context',
-        );
-      }
-    }
-    return maskedContext;
-  },
-
-  /**
-   * @param {object} currentContext
-   * @return {object}
-   * @private
-   */
-  _processChildContext: function(currentContext) {
-    var Component = this._currentElement.type;
-    var inst = this._instance;
-    var childContext;
-
-    if (typeof inst.getChildContext === 'function') {
-      if (__DEV__) {
-        ReactInstrumentation.debugTool.onBeginProcessingChildContext();
-        try {
-          childContext = inst.getChildContext();
-        } finally {
-          ReactInstrumentation.debugTool.onEndProcessingChildContext();
-        }
-      } else {
-        childContext = inst.getChildContext();
-      }
-
-      invariant(
-        typeof Component.childContextTypes === 'object',
-        '%s.getChildContext(): childContextTypes must be defined in order to ' +
-          'use getChildContext().',
-        this.getName() || 'ReactCompositeComponent',
-      );
-      if (__DEV__) {
-        this._checkContextTypes(
-          Component.childContextTypes,
-          childContext,
-          'child context',
-        );
-      }
-      for (var name in childContext) {
-        invariant(
-          name in Component.childContextTypes,
-          '%s.getChildContext(): key "%s" is not defined in childContextTypes.',
-          this.getName() || 'ReactCompositeComponent',
-          name,
-        );
-      }
-      return Object.assign({}, currentContext, childContext);
-    } else {
-      if (__DEV__) {
-        const componentName = this.getName();
-
-        if (!warningAboutMissingGetChildContext[componentName]) {
-          warningAboutMissingGetChildContext[componentName] = true;
-          warning(
-            !Component.childContextTypes,
-            '%s.childContextTypes is specified but there is no getChildContext() method ' +
-              'on the instance. You can either define getChildContext() on %s or remove ' +
-              'childContextTypes from it.',
-            componentName,
-            componentName,
-          );
-        }
-      }
-    }
-    return currentContext;
-  },
-
-  /**
-   * Assert that the context types are valid
-   *
-   * @param {object} typeSpecs Map of context field to a ReactPropType
-   * @param {object} values Runtime values that need to be type-checked
-   * @param {string} location e.g. "prop", "context", "child context"
-   * @private
-   */
-  _checkContextTypes: function(typeSpecs, values, location: string) {
-    if (__DEV__) {
-      ReactDebugCurrentStack.current = this._debugID;
-      checkPropTypes(
-        typeSpecs,
-        values,
-        location,
-        this.getName(),
-        ReactDebugCurrentStack.getStackAddendum,
-      );
-      ReactDebugCurrentStack.current = null;
-    }
-  },
-
-  receiveComponent: function(nextElement, transaction, nextContext) {
-    var prevElement = this._currentElement;
-    var prevContext = this._context;
-
-    this._pendingElement = null;
-
-    this.updateComponent(
-      transaction,
-      prevElement,
-      nextElement,
-      prevContext,
-      nextContext,
-    );
-  },
-
-  /**
-   * If any of `_pendingElement`, `_pendingStateQueue`, or `_pendingForceUpdate`
-   * is set, update the component.
-   *
-   * @param {ReactReconcileTransaction} transaction
-   * @internal
-   */
-  performUpdateIfNecessary: function(transaction) {
-    if (this._pendingElement != null) {
-      ReactReconciler.receiveComponent(
-        this,
-        this._pendingElement,
-        transaction,
-        this._context,
-      );
-    } else if (this._pendingStateQueue !== null || this._pendingForceUpdate) {
-      this.updateComponent(
-        transaction,
-        this._currentElement,
-        this._currentElement,
-        this._context,
-        this._context,
-      );
-    } else {
-      var callbacks = this._pendingCallbacks;
-      this._pendingCallbacks = null;
-      if (callbacks) {
-        for (var j = 0; j < callbacks.length; j++) {
-          transaction
-            .getReactMountReady()
-            .enqueue(callbacks[j], this.getPublicInstance());
-        }
-      }
-      this._updateBatchNumber = null;
-    }
-  },
-
-  /**
-   * Perform an update to a mounted component. The componentWillReceiveProps and
-   * shouldComponentUpdate methods are called, then (assuming the update isn't
-   * skipped) the remaining update lifecycle methods are called and the DOM
-   * representation is updated.
-   *
-   * By default, this implements React's rendering and reconciliation algorithm.
-   * Sophisticated clients may wish to override this.
-   *
-   * @param {ReactReconcileTransaction} transaction
-   * @param {ReactElement} prevParentElement
-   * @param {ReactElement} nextParentElement
-   * @internal
-   * @overridable
-   */
-  updateComponent: function(
-    transaction,
-    prevParentElement,
-    nextParentElement,
-    prevUnmaskedContext,
-    nextUnmaskedContext,
-  ) {
-    var inst = this._instance;
-    invariant(
-      inst != null,
-      'Attempted to update component `%s` that has already been unmounted ' +
-        '(or failed to mount).',
-      this.getName() || 'ReactCompositeComponent',
-    );
-
-    var willReceive = false;
-    var nextContext;
-
-    // Determine if the context has changed or not
-    if (this._context === nextUnmaskedContext) {
-      nextContext = inst.context;
-    } else {
-      nextContext = this._processContext(nextUnmaskedContext);
-      willReceive = true;
-    }
-
-    var prevProps = prevParentElement.props;
-    var nextProps = nextParentElement.props;
-
-    // Not a simple state update but a props update
-    if (prevParentElement !== nextParentElement) {
-      willReceive = true;
-    }
-
-    // An update here will schedule an update but immediately set
-    // _pendingStateQueue which will ensure that any state updates gets
-    // immediately reconciled instead of waiting for the next batch.
-    if (willReceive && inst.componentWillReceiveProps) {
-      const beforeState = inst.state;
-      if (__DEV__) {
-        measureLifeCyclePerf(
-          () => inst.componentWillReceiveProps(nextProps, nextContext),
-          this._debugID,
-          'componentWillReceiveProps',
-        );
-      } else {
-        inst.componentWillReceiveProps(nextProps, nextContext);
-      }
-      const afterState = inst.state;
-      if (beforeState !== afterState) {
-        inst.state = beforeState;
-        inst.updater.enqueueReplaceState(inst, afterState);
-        if (__DEV__) {
-          warning(
-            false,
-            '%s.componentWillReceiveProps(): Assigning directly to ' +
-              "this.state is deprecated (except inside a component's " +
-              'constructor). Use setState instead.',
-            this.getName() || 'ReactCompositeComponent',
-          );
-        }
-      }
-    }
-
-    // If updating happens to enqueue any new updates, we shouldn't execute new
-    // callbacks until the next render happens, so stash the callbacks first.
-    var callbacks = this._pendingCallbacks;
-    this._pendingCallbacks = null;
-
-    var nextState = this._processPendingState(nextProps, nextContext);
-    var shouldUpdate = true;
-    if (!this._pendingForceUpdate) {
-      var prevState = inst.state;
-      shouldUpdate = willReceive || nextState !== prevState;
-      if (inst.shouldComponentUpdate) {
-        if (__DEV__) {
-          shouldUpdate = measureLifeCyclePerf(
-            () => inst.shouldComponentUpdate(nextProps, nextState, nextContext),
-            this._debugID,
-            'shouldComponentUpdate',
-          );
-        } else {
-          shouldUpdate = inst.shouldComponentUpdate(
-            nextProps,
-            nextState,
-            nextContext,
-          );
-        }
-      } else {
-        if (this._compositeType === ReactCompositeComponentTypes.PureClass) {
-          shouldUpdate =
-            !shallowEqual(prevProps, nextProps) ||
-            !shallowEqual(inst.state, nextState);
-        }
-      }
-    }
-
-    if (__DEV__) {
-      warning(
-        shouldUpdate !== undefined,
-        '%s.shouldComponentUpdate(): Returned undefined instead of a ' +
-          'boolean value. Make sure to return true or false.',
-        this.getName() || 'ReactCompositeComponent',
-      );
-    }
-
-    this._updateBatchNumber = null;
-    if (shouldUpdate) {
-      this._pendingForceUpdate = false;
-      // Will set `this.props`, `this.state` and `this.context`.
-      this._performComponentUpdate(
-        nextParentElement,
-        nextProps,
-        nextState,
-        nextContext,
-        transaction,
-        nextUnmaskedContext,
-      );
-    } else {
-      // If it's determined that a component should not update, we still want
-      // to set props and state but we shortcut the rest of the update.
-      this._currentElement = nextParentElement;
-      this._context = nextUnmaskedContext;
-      inst.props = nextProps;
-      inst.state = nextState;
-      inst.context = nextContext;
-    }
-
-    if (callbacks) {
-      for (var j = 0; j < callbacks.length; j++) {
-        transaction
-          .getReactMountReady()
-          .enqueue(callbacks[j], this.getPublicInstance());
-      }
-    }
-  },
-
-  _processPendingState: function(props, context) {
-    var inst = this._instance;
-    var queue = this._pendingStateQueue;
-    var replace = this._pendingReplaceState;
-    this._pendingReplaceState = false;
-    this._pendingStateQueue = null;
-
-    if (!queue) {
-      return inst.state;
-    }
-
-    if (replace && queue.length === 1) {
-      return queue[0];
-    }
-
-    var nextState = replace ? queue[0] : inst.state;
-    var dontMutate = true;
-    for (var i = replace ? 1 : 0; i < queue.length; i++) {
-      var partial = queue[i];
-      let partialState = typeof partial === 'function'
-        ? partial.call(inst, nextState, props, context)
-        : partial;
-      if (partialState) {
-        if (dontMutate) {
-          dontMutate = false;
-          nextState = Object.assign({}, nextState, partialState);
-        } else {
-          Object.assign(nextState, partialState);
-        }
-      }
-    }
-
-    return nextState;
-  },
-
-  /**
-   * Merges new props and state, notifies delegate methods of update and
-   * performs update.
-   *
-   * @param {ReactElement} nextElement Next element
-   * @param {object} nextProps Next public object to set as properties.
-   * @param {?object} nextState Next object to set as state.
-   * @param {?object} nextContext Next public object to set as context.
-   * @param {ReactReconcileTransaction} transaction
-   * @param {?object} unmaskedContext
-   * @private
-   */
-  _performComponentUpdate: function(
-    nextElement,
-    nextProps,
-    nextState,
-    nextContext,
-    transaction,
-    unmaskedContext,
-  ) {
-    var inst = this._instance;
-
-    var hasComponentDidUpdate = !!inst.componentDidUpdate;
-    var prevProps;
-    var prevState;
-    if (hasComponentDidUpdate) {
-      prevProps = inst.props;
-      prevState = inst.state;
-    }
-
-    if (inst.componentWillUpdate) {
-      if (__DEV__) {
-        measureLifeCyclePerf(
-          () => inst.componentWillUpdate(nextProps, nextState, nextContext),
-          this._debugID,
-          'componentWillUpdate',
-        );
-      } else {
-        inst.componentWillUpdate(nextProps, nextState, nextContext);
-      }
-    }
-
-    this._currentElement = nextElement;
-    this._context = unmaskedContext;
-    inst.props = nextProps;
-    inst.state = nextState;
-    inst.context = nextContext;
-
-    if (inst.componentDidCatch) {
-      this._updateRenderedComponentWithErrorHandling(
-        transaction,
-        unmaskedContext,
-      );
-    } else {
-      this._updateRenderedComponent(transaction, unmaskedContext);
-    }
-
-    if (hasComponentDidUpdate) {
-      if (__DEV__) {
-        transaction.getReactMountReady().enqueue(() => {
-          measureLifeCyclePerf(
-            inst.componentDidUpdate.bind(inst, prevProps, prevState),
-            this._debugID,
-            'componentDidUpdate',
-          );
-        });
-      } else {
-        transaction
-          .getReactMountReady()
-          .enqueue(
-            inst.componentDidUpdate.bind(inst, prevProps, prevState),
-            inst,
-          );
-      }
-    }
-  },
-
-  /**
-   * Call the component's `render` method and update the DOM accordingly.
-   *
-   * @param {ReactReconcileTransaction} transaction
-   * @internal
-   */
-  _updateRenderedComponentWithErrorHandling: function(transaction, context) {
-    var checkpoint = transaction.checkpoint();
-    try {
-      this._updateRenderedComponent(transaction, context);
-    } catch (e) {
-      // Roll back to checkpoint, handle error (which may add items to the transaction),
-      // and take a new checkpoint
-      transaction.rollback(checkpoint);
-      this._instance.componentDidCatch(e);
-      if (this._pendingStateQueue) {
-        this._instance.state = this._processPendingState(
-          this._instance.props,
-          this._instance.context,
-        );
-      }
-      checkpoint = transaction.checkpoint();
-
-      // Gracefully update to a clean state
-      this._updateRenderedComponentWithNextElement(
-        transaction,
-        context,
-        null,
-        true /* safely */,
-      );
-
-      // Try again - we've informed the component about the error, so they can render an error message this time.
-      // If this throws again, the error will bubble up (and can be caught by a higher error boundary).
-      this._updateRenderedComponent(transaction, context);
-    }
-  },
-
-  /**
-   * Call the component's `render` method and update the DOM accordingly.
-   *
-   * @param {ReactReconcileTransaction} transaction
-   * @internal
-   */
-  _updateRenderedComponent: function(transaction, context) {
-    var nextRenderedElement = this._renderValidatedComponent();
-    this._updateRenderedComponentWithNextElement(
-      transaction,
-      context,
-      nextRenderedElement,
-      false /* safely */,
-    );
-  },
-
-  /**
-   * Call the component's `render` method and update the DOM accordingly.
-   *
-   * @param {ReactReconcileTransaction} transaction
-   * @internal
-   */
-  _updateRenderedComponentWithNextElement: function(
-    transaction,
-    context,
-    nextRenderedElement,
-    safely,
-  ) {
-    var prevComponentInstance = this._renderedComponent;
-    var prevRenderedElement = prevComponentInstance._currentElement;
-
-    var debugID = 0;
-    if (__DEV__) {
-      debugID = this._debugID;
-    }
-
-    if (shouldUpdateReactComponent(prevRenderedElement, nextRenderedElement)) {
-      ReactReconciler.receiveComponent(
-        prevComponentInstance,
-        nextRenderedElement,
-        transaction,
-        this._processChildContext(context),
-      );
-    } else {
-      var oldHostNode = ReactReconciler.getHostNode(prevComponentInstance);
-      var nodeType = ReactNodeTypes.getType(nextRenderedElement);
-      this._renderedNodeType = nodeType;
-      var child = this._instantiateReactComponent(
-        nextRenderedElement,
-        nodeType !== ReactNodeTypes.EMPTY /* shouldHaveDebugID */,
-      );
-      this._renderedComponent = child;
-
-      var nextMarkup = ReactReconciler.mountComponent(
-        child,
-        transaction,
-        this._hostParent,
-        this._hostContainerInfo,
-        this._processChildContext(context),
-        debugID,
-      );
-
-      ReactReconciler.unmountComponent(
-        prevComponentInstance,
-        safely,
-        false /* skipLifecycle */,
-      );
-
-      if (__DEV__) {
-        if (debugID !== 0) {
-          var childDebugIDs = child._debugID !== 0 ? [child._debugID] : [];
-          ReactInstrumentation.debugTool.onSetChildren(debugID, childDebugIDs);
-        }
-      }
-
-      this._replaceNodeWithMarkup(
-        oldHostNode,
-        nextMarkup,
-        prevComponentInstance,
-      );
-    }
-  },
-
-  /**
-   * Overridden in shallow rendering.
-   *
-   * @protected
-   */
-  _replaceNodeWithMarkup: function(oldHostNode, nextMarkup, prevInstance) {
-    ReactComponentEnvironment.replaceNodeWithMarkup(
-      oldHostNode,
-      nextMarkup,
-      prevInstance,
-    );
-  },
-
-  /**
-   * @protected
-   */
-  _renderValidatedComponentWithoutOwnerOrContext: function() {
-    var inst = this._instance;
-    var renderedElement;
-
-    if (__DEV__) {
-      renderedElement = measureLifeCyclePerf(
-        () => inst.render(),
-        this._debugID,
-        'render',
-      );
-    } else {
-      renderedElement = inst.render();
-    }
-
-    if (__DEV__) {
-      // We allow auto-mocks to proceed as if they're returning null.
-      if (renderedElement === undefined && inst.render._isMockFunction) {
-        // This is probably bad practice. Consider warning here and
-        // deprecating this convenience.
-        renderedElement = null;
-      }
-    }
-
-    return renderedElement;
-  },
-
-  /**
-   * @private
-   */
-  _renderValidatedComponent: function() {
-    var renderedElement;
-    if (
-      __DEV__ ||
-      this._compositeType !== ReactCompositeComponentTypes.StatelessFunctional
-    ) {
-      ReactCurrentOwner.current = this;
-      if (__DEV__) {
-        ReactDebugCurrentFrame.getCurrentStack =
-          ReactDebugCurrentStack.getStackAddendum;
-      }
-      try {
-        renderedElement = this._renderValidatedComponentWithoutOwnerOrContext();
-      } finally {
-        ReactCurrentOwner.current = null;
-        if (__DEV__) {
-          ReactDebugCurrentFrame.getCurrentStack = null;
-        }
-      }
-    } else {
-      renderedElement = this._renderValidatedComponentWithoutOwnerOrContext();
-    }
-    invariant(
-      // TODO: An `isValidNode` function would probably be more appropriate
-      renderedElement === null ||
-        renderedElement === false ||
-        React.isValidElement(renderedElement),
-      '%s.render(): A valid React element (or null) must be returned. You may have ' +
-        'returned undefined, an array or some other invalid object.',
-      this.getName() || 'ReactCompositeComponent',
-    );
-
-    return renderedElement;
-  },
-
-  /**
-   * Lazily allocates the refs object and stores `component` as `ref`.
-   *
-   * @param {string} ref Reference name.
-   * @param {component} component Component to store as `ref`.
-   * @final
-   * @private
-   */
-  attachRef: function(ref, component) {
-    var inst = this.getPublicInstance();
-    invariant(inst != null, 'Stateless function components cannot have refs.');
-    var publicComponentInstance = component.getPublicInstance();
-    var refs = inst.refs === emptyObject ? (inst.refs = {}) : inst.refs;
-    refs[ref] = publicComponentInstance;
-  },
-
-  /**
-   * Detaches a reference name.
-   *
-   * @param {string} ref Name to dereference.
-   * @final
-   * @private
-   */
-  detachRef: function(ref) {
-    var refs = this.getPublicInstance().refs;
-    delete refs[ref];
-  },
-
-  /**
-   * Get a text description of the component that can be used to identify it
-   * in error messages.
-   * @return {string} The name or null.
-   * @internal
-   */
-  getName: function() {
-    var type = this._currentElement.type;
-    var constructor = this._instance && this._instance.constructor;
-    return (
-      type.displayName ||
-      (constructor && constructor.displayName) ||
-      type.name ||
-      (constructor && constructor.name) ||
-      null
-    );
-  },
-
-  /**
-   * Get the publicly accessible representation of this component - i.e. what
-   * is exposed by refs and returned by render. Can be null for stateless
-   * components.
-   *
-   * @return {ReactComponent} the public component instance.
-   * @internal
-   */
-  getPublicInstance: function() {
-    var inst = this._instance;
-    if (
-      this._compositeType === ReactCompositeComponentTypes.StatelessFunctional
-    ) {
-      return null;
-    }
-    return inst;
-  },
-
-  // Stub
-  _instantiateReactComponent: null,
-};
-
-module.exports = ReactCompositeComponent;
diff --git a/src/renderers/shared/stack/reconciler/ReactCompositeComponentTypes.js b/src/renderers/shared/stack/reconciler/ReactCompositeComponentTypes.js
deleted file mode 100644
index e6f08250288..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactCompositeComponentTypes.js
+++ /dev/null
@@ -1,19 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactCompositeComponentTypes
- * @flow
- */
-
-export type CompositeComponentTypes = 0 | 1 | 2;
-
-module.exports = {
-  ImpureClass: 0,
-  PureClass: 1,
-  StatelessFunctional: 2,
-};
diff --git a/src/renderers/shared/stack/reconciler/ReactDebugCurrentStack.js b/src/renderers/shared/stack/reconciler/ReactDebugCurrentStack.js
deleted file mode 100644
index c7d4c7a312a..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactDebugCurrentStack.js
+++ /dev/null
@@ -1,38 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDebugCurrentStack
- * @flow
- */
-
-'use strict';
-
-import type {DebugID} from 'ReactInstanceType';
-
-const ReactDebugCurrentStack = {};
-
-if (__DEV__) {
-  var {ReactComponentTreeHook} = require('ReactGlobalSharedState');
-  var {getStackAddendumByID, getCurrentStackAddendum} = ReactComponentTreeHook;
-
-  // Component that is being worked on
-  ReactDebugCurrentStack.current = (null: DebugID | null);
-
-  ReactDebugCurrentStack.getStackAddendum = function(): string | null {
-    let stack = null;
-    const current = ReactDebugCurrentStack.current;
-    if (current !== null) {
-      stack = getStackAddendumByID(current);
-    } else {
-      stack = getCurrentStackAddendum();
-    }
-    return stack;
-  };
-}
-
-module.exports = ReactDebugCurrentStack;
diff --git a/src/renderers/shared/stack/reconciler/ReactDefaultBatchingStrategy.js b/src/renderers/shared/stack/reconciler/ReactDefaultBatchingStrategy.js
deleted file mode 100644
index f787eff3009..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactDefaultBatchingStrategy.js
+++ /dev/null
@@ -1,66 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactDefaultBatchingStrategy
- */
-
-'use strict';
-
-var ReactUpdates = require('ReactUpdates');
-var Transaction = require('Transaction');
-
-var emptyFunction = require('fbjs/lib/emptyFunction');
-
-var RESET_BATCHED_UPDATES = {
-  initialize: emptyFunction,
-  close: function() {
-    ReactDefaultBatchingStrategy.isBatchingUpdates = false;
-  },
-};
-
-var FLUSH_BATCHED_UPDATES = {
-  initialize: emptyFunction,
-  close: ReactUpdates.flushBatchedUpdates.bind(ReactUpdates),
-};
-
-var TRANSACTION_WRAPPERS = [FLUSH_BATCHED_UPDATES, RESET_BATCHED_UPDATES];
-
-function ReactDefaultBatchingStrategyTransaction() {
-  this.reinitializeTransaction();
-}
-
-Object.assign(ReactDefaultBatchingStrategyTransaction.prototype, Transaction, {
-  getTransactionWrappers: function() {
-    return TRANSACTION_WRAPPERS;
-  },
-});
-
-var transaction = new ReactDefaultBatchingStrategyTransaction();
-
-var ReactDefaultBatchingStrategy = {
-  isBatchingUpdates: false,
-
-  /**
-   * Call the provided function in a context within which calls to `setState`
-   * and friends are batched such that components aren't updated unnecessarily.
-   */
-  batchedUpdates: function(callback, a, b, c, d, e) {
-    var alreadyBatchingUpdates = ReactDefaultBatchingStrategy.isBatchingUpdates;
-
-    ReactDefaultBatchingStrategy.isBatchingUpdates = true;
-
-    // The code is written this way to avoid extra allocations
-    if (alreadyBatchingUpdates) {
-      return callback(a, b, c, d, e);
-    } else {
-      return transaction.perform(callback, null, a, b, c, d, e);
-    }
-  },
-};
-
-module.exports = ReactDefaultBatchingStrategy;
diff --git a/src/renderers/shared/stack/reconciler/ReactEmptyComponent.js b/src/renderers/shared/stack/reconciler/ReactEmptyComponent.js
deleted file mode 100644
index ddb228bae4d..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactEmptyComponent.js
+++ /dev/null
@@ -1,30 +0,0 @@
-/**
- * Copyright 2014-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactEmptyComponent
- */
-
-'use strict';
-
-var emptyComponentFactory;
-
-var ReactEmptyComponentInjection = {
-  injectEmptyComponentFactory: function(factory) {
-    emptyComponentFactory = factory;
-  },
-};
-
-var ReactEmptyComponent = {
-  create: function(instantiate) {
-    return emptyComponentFactory(instantiate);
-  },
-};
-
-ReactEmptyComponent.injection = ReactEmptyComponentInjection;
-
-module.exports = ReactEmptyComponent;
diff --git a/src/renderers/shared/stack/reconciler/ReactHostComponent.js b/src/renderers/shared/stack/reconciler/ReactHostComponent.js
deleted file mode 100644
index 5391ec289f3..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactHostComponent.js
+++ /dev/null
@@ -1,70 +0,0 @@
-/**
- * Copyright 2014-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactHostComponent
- */
-
-'use strict';
-
-var invariant = require('fbjs/lib/invariant');
-
-var genericComponentClass = null;
-var textComponentClass = null;
-
-var ReactHostComponentInjection = {
-  // This accepts a class that receives the tag string. This is a catch all
-  // that can render any kind of tag.
-  injectGenericComponentClass: function(componentClass) {
-    genericComponentClass = componentClass;
-  },
-  // This accepts a text component class that takes the text string to be
-  // rendered as props.
-  injectTextComponentClass: function(componentClass) {
-    textComponentClass = componentClass;
-  },
-};
-
-/**
- * Get a host internal component class for a specific tag.
- *
- * @param {ReactElement} element The element to create.
- * @return {function} The internal class constructor function.
- */
-function createInternalComponent(element) {
-  invariant(
-    genericComponentClass,
-    'There is no registered component for the tag %s',
-    element.type,
-  );
-  return new genericComponentClass(element);
-}
-
-/**
- * @param {ReactText} text
- * @return {ReactComponent}
- */
-function createInstanceForText(text) {
-  return new textComponentClass(text);
-}
-
-/**
- * @param {ReactComponent} component
- * @return {boolean}
- */
-function isTextComponent(component) {
-  return component instanceof textComponentClass;
-}
-
-var ReactHostComponent = {
-  createInternalComponent: createInternalComponent,
-  createInstanceForText: createInstanceForText,
-  isTextComponent: isTextComponent,
-  injection: ReactHostComponentInjection,
-};
-
-module.exports = ReactHostComponent;
diff --git a/src/renderers/shared/stack/reconciler/ReactInstanceType.js b/src/renderers/shared/stack/reconciler/ReactInstanceType.js
deleted file mode 100644
index 5b23ae46906..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactInstanceType.js
+++ /dev/null
@@ -1,49 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactInstanceType
- * @flow
- */
-
-'use strict';
-
-import type {ReactElement} from 'ReactElementType';
-import type {CompositeComponentTypes} from 'ReactCompositeComponentTypes';
-
-export type DebugID = number;
-
-export type ReactInstance = {
-  // Shared
-  mountComponent: any,
-  unmountComponent: any,
-  receiveComponent: any,
-  getName: () => string,
-  getPublicInstance: any,
-  _currentElement: ReactElement,
-
-  // ReactCompositeComponent
-  performInitialMountWithErrorHandling: any,
-  performInitialMount: any,
-  getHostNode: any,
-  performUpdateIfNecessary: any,
-  updateComponent: any,
-  attachRef: (ref: string, component: ReactInstance) => void,
-  detachRef: (ref: string) => void,
-  _rootNodeID: number,
-  _compositeType: CompositeComponentTypes,
-
-  // ReactDOMComponent
-  _tag: string,
-
-  // instantiateReactComponent
-  _mountIndex: number,
-  _mountImage: any,
-  // __DEV__
-  _debugID: DebugID,
-  _warnedAboutRefsInRender: boolean,
-};
diff --git a/src/renderers/shared/stack/reconciler/ReactMultiChild.js b/src/renderers/shared/stack/reconciler/ReactMultiChild.js
deleted file mode 100644
index be03aeb44c5..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactMultiChild.js
+++ /dev/null
@@ -1,546 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactMultiChild
- */
-
-'use strict';
-
-var ReactComponentEnvironment = require('ReactComponentEnvironment');
-var ReactInstanceMap = require('ReactInstanceMap');
-var ReactInstrumentation = require('ReactInstrumentation');
-
-var ReactReconciler = require('ReactReconciler');
-var ReactChildReconciler = require('ReactChildReconciler');
-var {ReactCurrentOwner} = require('ReactGlobalSharedState');
-if (__DEV__) {
-  var {ReactDebugCurrentFrame} = require('ReactGlobalSharedState');
-  var ReactDebugCurrentStack = require('ReactDebugCurrentStack');
-}
-
-var emptyFunction = require('fbjs/lib/emptyFunction');
-var flattenStackChildren = require('flattenStackChildren');
-var invariant = require('fbjs/lib/invariant');
-
-/**
- * Make an update for markup to be rendered and inserted at a supplied index.
- *
- * @param {string} markup Markup that renders into an element.
- * @param {number} toIndex Destination index.
- * @private
- */
-function makeInsertMarkup(markup, afterNode, toIndex) {
-  // NOTE: Null values reduce hidden classes.
-  return {
-    type: 'INSERT_MARKUP',
-    content: markup,
-    fromIndex: null,
-    fromNode: null,
-    toIndex: toIndex,
-    afterNode: afterNode,
-  };
-}
-
-/**
- * Make an update for moving an existing element to another index.
- *
- * @param {number} fromIndex Source index of the existing element.
- * @param {number} toIndex Destination index of the element.
- * @private
- */
-function makeMove(child, afterNode, toIndex) {
-  // NOTE: Null values reduce hidden classes.
-  return {
-    type: 'MOVE_EXISTING',
-    content: null,
-    fromIndex: child._mountIndex,
-    fromNode: ReactReconciler.getHostNode(child),
-    toIndex: toIndex,
-    afterNode: afterNode,
-  };
-}
-
-/**
- * Make an update for removing an element at an index.
- *
- * @param {number} fromIndex Index of the element to remove.
- * @private
- */
-function makeRemove(child, node) {
-  // NOTE: Null values reduce hidden classes.
-  return {
-    type: 'REMOVE_NODE',
-    content: null,
-    fromIndex: child._mountIndex,
-    fromNode: node,
-    toIndex: null,
-    afterNode: null,
-  };
-}
-
-/**
- * Make an update for setting the markup of a node.
- *
- * @param {string} markup Markup that renders into an element.
- * @private
- */
-function makeSetMarkup(markup) {
-  // NOTE: Null values reduce hidden classes.
-  return {
-    type: 'SET_MARKUP',
-    content: markup,
-    fromIndex: null,
-    fromNode: null,
-    toIndex: null,
-    afterNode: null,
-  };
-}
-
-/**
- * Make an update for setting the text content.
- *
- * @param {string} textContent Text content to set.
- * @private
- */
-function makeTextContent(textContent) {
-  // NOTE: Null values reduce hidden classes.
-  return {
-    type: 'TEXT_CONTENT',
-    content: textContent,
-    fromIndex: null,
-    fromNode: null,
-    toIndex: null,
-    afterNode: null,
-  };
-}
-
-/**
- * Push an update, if any, onto the queue. Creates a new queue if none is
- * passed and always returns the queue. Mutative.
- */
-function enqueue(queue, update) {
-  if (update) {
-    queue = queue || [];
-    queue.push(update);
-  }
-  return queue;
-}
-
-/**
- * Processes any enqueued updates.
- *
- * @private
- */
-function processQueue(inst, updateQueue) {
-  ReactComponentEnvironment.processChildrenUpdates(inst, updateQueue);
-}
-
-var setChildrenForInstrumentation = emptyFunction;
-if (__DEV__) {
-  var getDebugID = function(inst) {
-    if (!inst._debugID) {
-      // Check for ART-like instances. TODO: This is silly/gross.
-      var internal;
-      if ((internal = ReactInstanceMap.get(inst))) {
-        inst = internal;
-      }
-    }
-    return inst._debugID;
-  };
-  setChildrenForInstrumentation = function(children) {
-    var debugID = getDebugID(this);
-    // TODO: React Native empty components are also multichild.
-    // This means they still get into this method but don't have _debugID.
-    if (debugID !== 0) {
-      ReactInstrumentation.debugTool.onSetChildren(
-        debugID,
-        children
-          ? Object.keys(children).map(key => children[key]._debugID)
-          : [],
-      );
-    }
-  };
-}
-
-/**
- * Provides common functionality for components that must reconcile multiple
- * children. This is used by `ReactDOMComponent` to mount, update, and
- * unmount child components.
- */
-var ReactMultiChild = {
-  _reconcilerInstantiateChildren: function(
-    nestedChildren,
-    transaction,
-    context,
-  ) {
-    if (__DEV__) {
-      var selfDebugID = getDebugID(this);
-      if (this._currentElement) {
-        try {
-          ReactCurrentOwner.current = this._currentElement._owner;
-          ReactDebugCurrentFrame.getCurrentStack =
-            ReactDebugCurrentStack.getStackAddendum;
-          return ReactChildReconciler.instantiateChildren(
-            nestedChildren,
-            transaction,
-            context,
-            selfDebugID,
-          );
-        } finally {
-          ReactCurrentOwner.current = null;
-          ReactDebugCurrentFrame.getCurrentStack = null;
-        }
-      }
-    }
-    return ReactChildReconciler.instantiateChildren(
-      nestedChildren,
-      transaction,
-      context,
-    );
-  },
-
-  _reconcilerUpdateChildren: function(
-    prevChildren,
-    nextNestedChildrenElements,
-    mountImages,
-    removedNodes,
-    transaction,
-    context,
-  ) {
-    var nextChildren;
-    var selfDebugID = 0;
-    if (__DEV__) {
-      selfDebugID = getDebugID(this);
-      if (this._currentElement) {
-        try {
-          ReactCurrentOwner.current = this._currentElement._owner;
-          ReactDebugCurrentFrame.getCurrentStack =
-            ReactDebugCurrentStack.getStackAddendum;
-          nextChildren = flattenStackChildren(
-            nextNestedChildrenElements,
-            selfDebugID,
-          );
-        } finally {
-          ReactCurrentOwner.current = null;
-          ReactDebugCurrentFrame.getCurrentStack = null;
-        }
-        ReactChildReconciler.updateChildren(
-          prevChildren,
-          nextChildren,
-          mountImages,
-          removedNodes,
-          transaction,
-          this,
-          this._hostContainerInfo,
-          context,
-          selfDebugID,
-        );
-        return nextChildren;
-      }
-    }
-    nextChildren = flattenStackChildren(
-      nextNestedChildrenElements,
-      selfDebugID,
-    );
-    ReactChildReconciler.updateChildren(
-      prevChildren,
-      nextChildren,
-      mountImages,
-      removedNodes,
-      transaction,
-      this,
-      this._hostContainerInfo,
-      context,
-      selfDebugID,
-    );
-    return nextChildren;
-  },
-
-  /**
-   * Generates a "mount image" for each of the supplied children. In the case
-   * of `ReactDOMComponent`, a mount image is a string of markup.
-   *
-   * @param {?object} nestedChildren Nested child maps.
-   * @return {array} An array of mounted representations.
-   * @internal
-   */
-  mountChildren: function(nestedChildren, transaction, context) {
-    var children = this._reconcilerInstantiateChildren(
-      nestedChildren,
-      transaction,
-      context,
-    );
-    this._renderedChildren = children;
-
-    var mountImages = [];
-    var index = 0;
-    for (var name in children) {
-      if (children.hasOwnProperty(name)) {
-        var child = children[name];
-        var selfDebugID = 0;
-        if (__DEV__) {
-          selfDebugID = getDebugID(this);
-        }
-        var mountImage = ReactReconciler.mountComponent(
-          child,
-          transaction,
-          this,
-          this._hostContainerInfo,
-          context,
-          selfDebugID,
-        );
-        child._mountIndex = index++;
-        mountImages.push(mountImage);
-      }
-    }
-
-    if (__DEV__) {
-      setChildrenForInstrumentation.call(this, children);
-    }
-
-    return mountImages;
-  },
-
-  /**
-   * Replaces any rendered children with a text content string.
-   *
-   * @param {string} nextContent String of content.
-   * @internal
-   */
-  updateTextContent: function(nextContent) {
-    var prevChildren = this._renderedChildren;
-    // Remove any rendered children.
-    ReactChildReconciler.unmountChildren(
-      prevChildren,
-      false /* safely */,
-      false /* skipLifecycle */,
-    );
-    for (var name in prevChildren) {
-      if (prevChildren.hasOwnProperty(name)) {
-        invariant(false, 'updateTextContent called on non-empty component.');
-      }
-    }
-    // Set new text content.
-    var updates = [makeTextContent(nextContent)];
-    processQueue(this, updates);
-  },
-
-  /**
-   * Replaces any rendered children with a markup string.
-   *
-   * @param {string} nextMarkup String of markup.
-   * @internal
-   */
-  updateMarkup: function(nextMarkup) {
-    var prevChildren = this._renderedChildren;
-    // Remove any rendered children.
-    ReactChildReconciler.unmountChildren(
-      prevChildren,
-      false /* safely */,
-      false /* skipLifecycle */,
-    );
-    for (var name in prevChildren) {
-      if (prevChildren.hasOwnProperty(name)) {
-        invariant(false, 'updateTextContent called on non-empty component.');
-      }
-    }
-    var updates = [makeSetMarkup(nextMarkup)];
-    processQueue(this, updates);
-  },
-
-  /**
-   * Updates the rendered children with new children.
-   *
-   * @param {?object} nextNestedChildrenElements Nested child element maps.
-   * @param {ReactReconcileTransaction} transaction
-   * @internal
-   */
-  updateChildren: function(nextNestedChildrenElements, transaction, context) {
-    // Hook used by React ART
-    this._updateChildren(nextNestedChildrenElements, transaction, context);
-  },
-
-  /**
-   * @param {?object} nextNestedChildrenElements Nested child element maps.
-   * @param {ReactReconcileTransaction} transaction
-   * @final
-   * @protected
-   */
-  _updateChildren: function(nextNestedChildrenElements, transaction, context) {
-    var prevChildren = this._renderedChildren;
-    var removedNodes = {};
-    var mountImages = [];
-    var nextChildren = this._reconcilerUpdateChildren(
-      prevChildren,
-      nextNestedChildrenElements,
-      mountImages,
-      removedNodes,
-      transaction,
-      context,
-    );
-    if (!nextChildren && !prevChildren) {
-      return;
-    }
-    var updates = null;
-    var name;
-    // `nextIndex` will increment for each child in `nextChildren`, but
-    // `lastIndex` will be the last index visited in `prevChildren`.
-    var nextIndex = 0;
-    var lastIndex = 0;
-    // `nextMountIndex` will increment for each newly mounted child.
-    var nextMountIndex = 0;
-    var lastPlacedNode = null;
-    for (name in nextChildren) {
-      if (!nextChildren.hasOwnProperty(name)) {
-        continue;
-      }
-      var prevChild = prevChildren && prevChildren[name];
-      var nextChild = nextChildren[name];
-      if (prevChild === nextChild) {
-        updates = enqueue(
-          updates,
-          this.moveChild(prevChild, lastPlacedNode, nextIndex, lastIndex),
-        );
-        lastIndex = Math.max(prevChild._mountIndex, lastIndex);
-        prevChild._mountIndex = nextIndex;
-      } else {
-        if (prevChild) {
-          // Update `lastIndex` before `_mountIndex` gets unset by unmounting.
-          lastIndex = Math.max(prevChild._mountIndex, lastIndex);
-          // The `removedNodes` loop below will actually remove the child.
-        }
-        // The child must be instantiated before it's mounted.
-        updates = enqueue(
-          updates,
-          this._mountChildAtIndex(
-            nextChild,
-            mountImages[nextMountIndex],
-            lastPlacedNode,
-            nextIndex,
-            transaction,
-            context,
-          ),
-        );
-        nextMountIndex++;
-      }
-      nextIndex++;
-      lastPlacedNode = ReactReconciler.getHostNode(nextChild);
-    }
-    // Remove children that are no longer present.
-    for (name in removedNodes) {
-      if (removedNodes.hasOwnProperty(name)) {
-        updates = enqueue(
-          updates,
-          this._unmountChild(prevChildren[name], removedNodes[name]),
-        );
-      }
-    }
-    if (updates) {
-      processQueue(this, updates);
-    }
-    this._renderedChildren = nextChildren;
-
-    if (__DEV__) {
-      setChildrenForInstrumentation.call(this, nextChildren);
-    }
-  },
-
-  /**
-   * Unmounts all rendered children. This should be used to clean up children
-   * when this component is unmounted. It does not actually perform any
-   * backend operations.
-   *
-   * @internal
-   */
-  unmountChildren: function(safely, skipLifecycle) {
-    var renderedChildren = this._renderedChildren;
-    ReactChildReconciler.unmountChildren(
-      renderedChildren,
-      safely,
-      skipLifecycle,
-    );
-    this._renderedChildren = null;
-  },
-
-  /**
-   * Moves a child component to the supplied index.
-   *
-   * @param {ReactComponent} child Component to move.
-   * @param {number} toIndex Destination index of the element.
-   * @param {number} lastIndex Last index visited of the siblings of `child`.
-   * @protected
-   */
-  moveChild: function(child, afterNode, toIndex, lastIndex) {
-    // If the index of `child` is less than `lastIndex`, then it needs to
-    // be moved. Otherwise, we do not need to move it because a child will be
-    // inserted or moved before `child`.
-    if (child._mountIndex < lastIndex) {
-      return makeMove(child, afterNode, toIndex);
-    }
-  },
-
-  /**
-   * Creates a child component.
-   *
-   * @param {ReactComponent} child Component to create.
-   * @param {string} mountImage Markup to insert.
-   * @protected
-   */
-  createChild: function(child, afterNode, mountImage) {
-    return makeInsertMarkup(mountImage, afterNode, child._mountIndex);
-  },
-
-  /**
-   * Removes a child component.
-   *
-   * @param {ReactComponent} child Child to remove.
-   * @protected
-   */
-  removeChild: function(child, node) {
-    return makeRemove(child, node);
-  },
-
-  /**
-   * Mounts a child with the supplied name.
-   *
-   * NOTE: This is part of `updateChildren` and is here for readability.
-   *
-   * @param {ReactComponent} child Component to mount.
-   * @param {string} name Name of the child.
-   * @param {number} index Index at which to insert the child.
-   * @param {ReactReconcileTransaction} transaction
-   * @private
-   */
-  _mountChildAtIndex: function(
-    child,
-    mountImage,
-    afterNode,
-    index,
-    transaction,
-    context,
-  ) {
-    child._mountIndex = index;
-    return this.createChild(child, afterNode, mountImage);
-  },
-
-  /**
-   * Unmounts a rendered child.
-   *
-   * NOTE: This is part of `updateChildren` and is here for readability.
-   *
-   * @param {ReactComponent} child Component to unmount.
-   * @private
-   */
-  _unmountChild: function(child, node) {
-    var update = this.removeChild(child, node);
-    child._mountIndex = null;
-    return update;
-  },
-};
-
-module.exports = ReactMultiChild;
diff --git a/src/renderers/shared/stack/reconciler/ReactMultiChildUpdateTypes.js b/src/renderers/shared/stack/reconciler/ReactMultiChildUpdateTypes.js
deleted file mode 100644
index 1319db50fae..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactMultiChildUpdateTypes.js
+++ /dev/null
@@ -1,25 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactMultiChildUpdateTypes
- */
-
-'use strict';
-
-/**
- * When a component's children are updated, a series of update configuration
- * objects are created in order to batch and serialize the required changes.
- *
- * Enumerates all the possible types of update configurations.
- */
-export type ReactMultiChildUpdateTypes =
-  | 'INSERT_MARKUP'
-  | 'MOVE_EXISTING'
-  | 'REMOVE_NODE'
-  | 'SET_MARKUP'
-  | 'TEXT_CONTENT';
diff --git a/src/renderers/shared/stack/reconciler/ReactNodeTypes.js b/src/renderers/shared/stack/reconciler/ReactNodeTypes.js
deleted file mode 100644
index 2e24a6ba10d..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactNodeTypes.js
+++ /dev/null
@@ -1,40 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactNodeTypes
- * @flow
- */
-
-'use strict';
-
-type ReactNodeType = 0 | 1 | 2;
-
-var React = require('react');
-
-var invariant = require('fbjs/lib/invariant');
-
-var ReactNodeTypes = {
-  HOST: 0,
-  COMPOSITE: 1,
-  EMPTY: 2,
-
-  getType: function(node: ReactElement<any>): ReactNodeType {
-    if (node === null || node === false) {
-      return ReactNodeTypes.EMPTY;
-    } else if (React.isValidElement(node)) {
-      if (typeof node.type === 'function') {
-        return ReactNodeTypes.COMPOSITE;
-      } else {
-        return ReactNodeTypes.HOST;
-      }
-    }
-    invariant(false, 'Unexpected node: %s', node);
-  },
-};
-
-module.exports = ReactNodeTypes;
diff --git a/src/renderers/shared/stack/reconciler/ReactOwner.js b/src/renderers/shared/stack/reconciler/ReactOwner.js
deleted file mode 100644
index 7d3a4c60323..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactOwner.js
+++ /dev/null
@@ -1,135 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactOwner
- * @flow
- */
-
-'use strict';
-
-var {ClassComponent} = require('ReactTypeOfWork');
-
-var emptyObject = require('fbjs/lib/emptyObject');
-var invariant = require('fbjs/lib/invariant');
-
-import type {Fiber} from 'ReactFiber';
-import type {ReactInstance} from 'ReactInstanceType';
-
-/**
- * @param {?object} object
- * @return {boolean} True if `object` is a valid owner.
- * @final
- */
-function isValidOwner(object: any): boolean {
-  return !!(object &&
-    typeof object.attachRef === 'function' &&
-    typeof object.detachRef === 'function');
-}
-
-/**
- * ReactOwners are capable of storing references to owned components.
- *
- * All components are capable of //being// referenced by owner components, but
- * only ReactOwner components are capable of //referencing// owned components.
- * The named reference is known as a "ref".
- *
- * Refs are available when mounted and updated during reconciliation.
- *
- *   var MyComponent = React.createClass({
- *     render: function() {
- *       return (
- *         <div onClick={this.handleClick}>
- *           <CustomComponent ref="custom" />
- *         </div>
- *       );
- *     },
- *     handleClick: function() {
- *       this.refs.custom.handleClick();
- *     },
- *     componentDidMount: function() {
- *       this.refs.custom.initialize();
- *     }
- *   });
- *
- * Refs should rarely be used. When refs are used, they should only be done to
- * control data that is not handled by React's data flow.
- *
- * @class ReactOwner
- */
-var ReactOwner = {
-  /**
-   * Adds a component by ref to an owner component.
-   *
-   * @param {ReactComponent} component Component to reference.
-   * @param {string} ref Name by which to refer to the component.
-   * @param {ReactOwner} owner Component on which to record the ref.
-   * @final
-   * @internal
-   */
-  addComponentAsRefTo: function(
-    component: ReactInstance,
-    ref: string,
-    owner: ReactInstance | Fiber,
-  ): void {
-    if (owner && (owner: any).tag === ClassComponent) {
-      const inst = (owner: any).stateNode;
-      const refs = inst.refs === emptyObject ? (inst.refs = {}) : inst.refs;
-      refs[ref] = component.getPublicInstance();
-    } else {
-      invariant(
-        isValidOwner(owner),
-        'addComponentAsRefTo(...): Only a ReactOwner can have refs. You might ' +
-          "be adding a ref to a component that was not created inside a component's " +
-          '`render` method, or you have multiple copies of React loaded ' +
-          '(details: https://fb.me/react-refs-must-have-owner).',
-      );
-      (owner: any).attachRef(ref, component);
-    }
-  },
-
-  /**
-   * Removes a component by ref from an owner component.
-   *
-   * @param {ReactComponent} component Component to dereference.
-   * @param {string} ref Name of the ref to remove.
-   * @param {ReactOwner} owner Component on which the ref is recorded.
-   * @final
-   * @internal
-   */
-  removeComponentAsRefFrom: function(
-    component: ReactInstance,
-    ref: string,
-    owner: ReactInstance | Fiber,
-  ): void {
-    if (owner && (owner: any).tag === ClassComponent) {
-      const inst = (owner: any).stateNode;
-      if (inst && inst.refs[ref] === component.getPublicInstance()) {
-        delete inst.refs[ref];
-      }
-    } else {
-      invariant(
-        isValidOwner(owner),
-        'removeComponentAsRefFrom(...): Only a ReactOwner can have refs. You might ' +
-          "be removing a ref to a component that was not created inside a component's " +
-          '`render` method, or you have multiple copies of React loaded ' +
-          '(details: https://fb.me/react-refs-must-have-owner).',
-      );
-      var ownerPublicInstance = (owner: any).getPublicInstance();
-      // Check that `component`'s owner is still alive and that `component` is still the current ref
-      // because we do not want to detach the ref if another component stole it.
-      if (
-        ownerPublicInstance &&
-        ownerPublicInstance.refs[ref] === component.getPublicInstance()
-      ) {
-        (owner: any).detachRef(ref);
-      }
-    }
-  },
-};
-
-module.exports = ReactOwner;
diff --git a/src/renderers/shared/stack/reconciler/ReactReconciler.js b/src/renderers/shared/stack/reconciler/ReactReconciler.js
deleted file mode 100644
index 4250b701419..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactReconciler.js
+++ /dev/null
@@ -1,225 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactReconciler
- */
-
-'use strict';
-
-var ReactRef = require('ReactRef');
-var ReactInstrumentation = require('ReactInstrumentation');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
-/**
- * Helper to call ReactRef.attachRefs with this composite component, split out
- * to avoid allocations in the transaction mount-ready queue.
- */
-function attachRefs() {
-  ReactRef.attachRefs(this, this._currentElement);
-}
-
-var ReactReconciler = {
-  /**
-   * Initializes the component, renders markup, and registers event listeners.
-   *
-   * @param {ReactComponent} internalInstance
-   * @param {ReactReconcileTransaction|ReactServerRenderingTransaction} transaction
-   * @param {?object} the containing host component instance
-   * @param {?object} info about the host container
-   * @return {?string} Rendered markup to be inserted into the DOM.
-   * @final
-   * @internal
-   */
-  mountComponent: function(
-    internalInstance,
-    transaction,
-    hostParent,
-    hostContainerInfo,
-    context,
-    parentDebugID, // 0 in production and for roots
-  ) {
-    if (__DEV__) {
-      if (internalInstance._debugID !== 0) {
-        ReactInstrumentation.debugTool.onBeforeMountComponent(
-          internalInstance._debugID,
-          internalInstance._currentElement,
-          parentDebugID,
-        );
-      }
-    }
-    var markup = internalInstance.mountComponent(
-      transaction,
-      hostParent,
-      hostContainerInfo,
-      context,
-      parentDebugID,
-    );
-    if (
-      internalInstance._currentElement &&
-      internalInstance._currentElement.ref != null
-    ) {
-      transaction.getReactMountReady().enqueue(attachRefs, internalInstance);
-    }
-    if (__DEV__) {
-      if (internalInstance._debugID !== 0) {
-        ReactInstrumentation.debugTool.onMountComponent(
-          internalInstance._debugID,
-        );
-      }
-    }
-    return markup;
-  },
-
-  /**
-   * Returns a value that can be passed to
-   * ReactComponentEnvironment.replaceNodeWithMarkup.
-   */
-  getHostNode: function(internalInstance) {
-    return internalInstance.getHostNode();
-  },
-
-  /**
-   * Releases any resources allocated by `mountComponent`.
-   *
-   * @final
-   * @internal
-   */
-  unmountComponent: function(internalInstance, safely, skipLifecycle) {
-    if (__DEV__) {
-      if (internalInstance._debugID !== 0) {
-        ReactInstrumentation.debugTool.onBeforeUnmountComponent(
-          internalInstance._debugID,
-        );
-      }
-    }
-    ReactRef.detachRefs(internalInstance, internalInstance._currentElement);
-    internalInstance.unmountComponent(safely, skipLifecycle);
-    if (__DEV__) {
-      if (internalInstance._debugID !== 0) {
-        ReactInstrumentation.debugTool.onUnmountComponent(
-          internalInstance._debugID,
-        );
-      }
-    }
-  },
-
-  /**
-   * Update a component using a new element.
-   *
-   * @param {ReactComponent} internalInstance
-   * @param {ReactElement} nextElement
-   * @param {ReactReconcileTransaction} transaction
-   * @param {object} context
-   * @internal
-   */
-  receiveComponent: function(
-    internalInstance,
-    nextElement,
-    transaction,
-    context,
-  ) {
-    var prevElement = internalInstance._currentElement;
-
-    if (nextElement === prevElement && context === internalInstance._context) {
-      // Since elements are immutable after the owner is rendered,
-      // we can do a cheap identity compare here to determine if this is a
-      // superfluous reconcile. It's possible for state to be mutable but such
-      // change should trigger an update of the owner which would recreate
-      // the element. We explicitly check for the existence of an owner since
-      // it's possible for an element created outside a composite to be
-      // deeply mutated and reused.
-
-      // TODO: Bailing out early is just a perf optimization right?
-      // TODO: Removing the return statement should affect correctness?
-      return;
-    }
-
-    if (__DEV__) {
-      if (internalInstance._debugID !== 0) {
-        ReactInstrumentation.debugTool.onBeforeUpdateComponent(
-          internalInstance._debugID,
-          nextElement,
-        );
-      }
-    }
-
-    var refsChanged = ReactRef.shouldUpdateRefs(prevElement, nextElement);
-
-    if (refsChanged) {
-      ReactRef.detachRefs(internalInstance, prevElement);
-    }
-
-    internalInstance.receiveComponent(nextElement, transaction, context);
-
-    if (
-      refsChanged &&
-      internalInstance._currentElement &&
-      internalInstance._currentElement.ref != null
-    ) {
-      transaction.getReactMountReady().enqueue(attachRefs, internalInstance);
-    }
-
-    if (__DEV__) {
-      if (internalInstance._debugID !== 0) {
-        ReactInstrumentation.debugTool.onUpdateComponent(
-          internalInstance._debugID,
-        );
-      }
-    }
-  },
-
-  /**
-   * Flush any dirty changes in a component.
-   *
-   * @param {ReactComponent} internalInstance
-   * @param {ReactReconcileTransaction} transaction
-   * @internal
-   */
-  performUpdateIfNecessary: function(
-    internalInstance,
-    transaction,
-    updateBatchNumber,
-  ) {
-    if (internalInstance._updateBatchNumber !== updateBatchNumber) {
-      if (__DEV__) {
-        // The component's enqueued batch number should always be the current
-        // batch or the following one.
-        warning(
-          internalInstance._updateBatchNumber == null ||
-            internalInstance._updateBatchNumber === updateBatchNumber + 1,
-          'performUpdateIfNecessary: Unexpected batch number (current %s, ' +
-            'pending %s)',
-          updateBatchNumber,
-          internalInstance._updateBatchNumber,
-        );
-      }
-      return;
-    }
-    if (__DEV__) {
-      if (internalInstance._debugID !== 0) {
-        ReactInstrumentation.debugTool.onBeforeUpdateComponent(
-          internalInstance._debugID,
-          internalInstance._currentElement,
-        );
-      }
-    }
-    internalInstance.performUpdateIfNecessary(transaction);
-    if (__DEV__) {
-      if (internalInstance._debugID !== 0) {
-        ReactInstrumentation.debugTool.onUpdateComponent(
-          internalInstance._debugID,
-        );
-      }
-    }
-  },
-};
-
-module.exports = ReactReconciler;
diff --git a/src/renderers/shared/stack/reconciler/ReactRef.js b/src/renderers/shared/stack/reconciler/ReactRef.js
deleted file mode 100644
index de656b02396..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactRef.js
+++ /dev/null
@@ -1,146 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactRef
- * @flow
- */
-
-'use strict';
-
-var ReactOwner = require('ReactOwner');
-
-import type {ReactInstance} from 'ReactInstanceType';
-import type {ReactElement} from 'ReactElementType';
-
-var ReactRef = {};
-
-if (__DEV__) {
-  var ReactCompositeComponentTypes = require('ReactCompositeComponentTypes');
-  var {ReactComponentTreeHook} = require('ReactGlobalSharedState');
-  var warning = require('fbjs/lib/warning');
-
-  var warnedAboutStatelessRefs = {};
-}
-
-function attachRef(ref, component, owner) {
-  if (__DEV__) {
-    if (
-      component._compositeType ===
-      ReactCompositeComponentTypes.StatelessFunctional
-    ) {
-      let info = '';
-      let ownerName;
-      if (owner) {
-        if (typeof owner.getName === 'function') {
-          ownerName = owner.getName();
-        }
-        if (ownerName) {
-          info += '\n\nCheck the render method of `' + ownerName + '`.';
-        }
-      }
-
-      let warningKey = ownerName || component._debugID;
-      let element = component._currentElement;
-      if (element && element._source) {
-        warningKey =
-          element._source.fileName + ':' + element._source.lineNumber;
-      }
-      if (!warnedAboutStatelessRefs[warningKey]) {
-        warnedAboutStatelessRefs[warningKey] = true;
-        warning(
-          false,
-          'Stateless function components cannot be given refs. ' +
-            'Attempts to access this ref will fail.%s%s',
-          info,
-          ReactComponentTreeHook.getStackAddendumByID(component._debugID),
-        );
-      }
-    }
-  }
-
-  if (typeof ref === 'function') {
-    ref(component.getPublicInstance());
-  } else {
-    // Legacy ref
-    ReactOwner.addComponentAsRefTo(component, ref, owner);
-  }
-}
-
-function detachRef(ref, component, owner) {
-  if (typeof ref === 'function') {
-    ref(null);
-  } else {
-    // Legacy ref
-    ReactOwner.removeComponentAsRefFrom(component, ref, owner);
-  }
-}
-
-ReactRef.attachRefs = function(
-  instance: ReactInstance,
-  element: ReactElement | string | number | null | false,
-): void {
-  if (element === null || typeof element !== 'object') {
-    return;
-  }
-  var ref = element.ref;
-  if (ref != null) {
-    attachRef(ref, instance, element._owner);
-  }
-};
-
-ReactRef.shouldUpdateRefs = function(
-  prevElement: ReactElement | string | number | null | false,
-  nextElement: ReactElement | string | number | null | false,
-): boolean {
-  // If either the owner or a `ref` has changed, make sure the newest owner
-  // has stored a reference to `this`, and the previous owner (if different)
-  // has forgotten the reference to `this`. We use the element instead
-  // of the public this.props because the post processing cannot determine
-  // a ref. The ref conceptually lives on the element.
-
-  // TODO: Should this even be possible? The owner cannot change because
-  // it's forbidden by shouldUpdateReactComponent. The ref can change
-  // if you swap the keys of but not the refs. Reconsider where this check
-  // is made. It probably belongs where the key checking and
-  // instantiateReactComponent is done.
-
-  var prevRef = null;
-  var prevOwner = null;
-  if (prevElement !== null && typeof prevElement === 'object') {
-    prevRef = prevElement.ref;
-    prevOwner = prevElement._owner;
-  }
-
-  var nextRef = null;
-  var nextOwner = null;
-  if (nextElement !== null && typeof nextElement === 'object') {
-    nextRef = nextElement.ref;
-    nextOwner = nextElement._owner;
-  }
-
-  return (
-    prevRef !== nextRef ||
-    // If owner changes but we have an unchanged function ref, don't update refs
-    (typeof nextRef === 'string' && nextOwner !== prevOwner)
-  );
-};
-
-ReactRef.detachRefs = function(
-  instance: ReactInstance,
-  element: ReactElement | string | number | null | false,
-): void {
-  if (element === null || typeof element !== 'object') {
-    return;
-  }
-  var ref = element.ref;
-  if (ref != null) {
-    detachRef(ref, instance, element._owner);
-  }
-};
-
-module.exports = ReactRef;
diff --git a/src/renderers/shared/stack/reconciler/ReactSimpleEmptyComponent.js b/src/renderers/shared/stack/reconciler/ReactSimpleEmptyComponent.js
deleted file mode 100644
index f7159ef736c..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactSimpleEmptyComponent.js
+++ /dev/null
@@ -1,51 +0,0 @@
-/**
- * Copyright 2014-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactSimpleEmptyComponent
- */
-
-'use strict';
-
-var ReactReconciler = require('ReactReconciler');
-
-var ReactSimpleEmptyComponent = function(placeholderElement, instantiate) {
-  this._currentElement = null;
-  this._renderedComponent = instantiate(placeholderElement);
-};
-Object.assign(ReactSimpleEmptyComponent.prototype, {
-  mountComponent: function(
-    transaction,
-    hostParent,
-    hostContainerInfo,
-    context,
-    parentDebugID, // 0 in production and for roots
-  ) {
-    return ReactReconciler.mountComponent(
-      this._renderedComponent,
-      transaction,
-      hostParent,
-      hostContainerInfo,
-      context,
-      parentDebugID,
-    );
-  },
-  receiveComponent: function() {},
-  getHostNode: function() {
-    return ReactReconciler.getHostNode(this._renderedComponent);
-  },
-  unmountComponent: function(safely, skipLifecycle) {
-    ReactReconciler.unmountComponent(
-      this._renderedComponent,
-      safely,
-      skipLifecycle,
-    );
-    this._renderedComponent = null;
-  },
-});
-
-module.exports = ReactSimpleEmptyComponent;
diff --git a/src/renderers/shared/stack/reconciler/ReactUpdateQueue.js b/src/renderers/shared/stack/reconciler/ReactUpdateQueue.js
deleted file mode 100644
index 778936380e9..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactUpdateQueue.js
+++ /dev/null
@@ -1,257 +0,0 @@
-/**
- * Copyright 2015-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactUpdateQueue
- */
-
-'use strict';
-
-var ReactInstanceMap = require('ReactInstanceMap');
-var ReactInstrumentation = require('ReactInstrumentation');
-var ReactUpdates = require('ReactUpdates');
-var {ReactCurrentOwner} = require('ReactGlobalSharedState');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var warnOnInvalidCallback = function(callback: mixed, callerName: string) {
-    warning(
-      callback === null || typeof callback === 'function',
-      '%s(...): Expected the last optional `callback` argument to be a ' +
-        'function. Instead received: %s.',
-      callerName,
-      '' + callback,
-    );
-  };
-}
-
-function enqueueUpdate(internalInstance) {
-  ReactUpdates.enqueueUpdate(internalInstance);
-}
-
-function getInternalInstanceReadyForUpdate(publicInstance, callerName) {
-  var internalInstance = ReactInstanceMap.get(publicInstance);
-  if (!internalInstance) {
-    if (__DEV__) {
-      var ctor = publicInstance.constructor;
-      warning(
-        false,
-        'Can only update a mounted or mounting component. This usually means ' +
-          'you called setState, replaceState, or forceUpdate on an unmounted ' +
-          'component. This is a no-op.\n\nPlease check the code for the ' +
-          '%s component.',
-        (ctor && (ctor.displayName || ctor.name)) || 'ReactClass',
-      );
-    }
-    return null;
-  }
-
-  if (__DEV__) {
-    warning(
-      ReactCurrentOwner.current == null,
-      'Cannot update during an existing state transition (such as within ' +
-        "`render` or another component's constructor). Render methods should " +
-        'be a pure function of props and state; constructor side-effects are ' +
-        'an anti-pattern, but can be moved to `componentWillMount`.',
-    );
-  }
-
-  return internalInstance;
-}
-
-/**
- * ReactUpdateQueue allows for state updates to be scheduled into a later
- * reconciliation step.
- */
-var ReactUpdateQueue = {
-  /**
-   * Checks whether or not this composite component is mounted.
-   * @param {ReactClass} publicInstance The instance we want to test.
-   * @return {boolean} True if mounted, false otherwise.
-   * @protected
-   * @final
-   */
-  isMounted: function(publicInstance) {
-    if (__DEV__) {
-      var owner = ReactCurrentOwner.current;
-      if (owner !== null) {
-        warning(
-          owner._warnedAboutRefsInRender,
-          '%s is accessing isMounted inside its render() function. ' +
-            'render() should be a pure function of props and state. It should ' +
-            'never access something that requires stale data from the previous ' +
-            'render, such as refs. Move this logic to componentDidMount and ' +
-            'componentDidUpdate instead.',
-          owner.getName() || 'A component',
-        );
-        owner._warnedAboutRefsInRender = true;
-      }
-    }
-    var internalInstance = ReactInstanceMap.get(publicInstance);
-    if (internalInstance) {
-      // During componentWillMount and render this will still be null but after
-      // that will always render to something. At least for now. So we can use
-      // this hack.
-      return !!internalInstance._renderedComponent;
-    } else {
-      return false;
-    }
-  },
-
-  enqueueCallbackInternal: function(internalInstance, callback) {
-    if (internalInstance._pendingCallbacks) {
-      internalInstance._pendingCallbacks.push(callback);
-    } else {
-      internalInstance._pendingCallbacks = [callback];
-    }
-    enqueueUpdate(internalInstance);
-  },
-
-  /**
-   * Forces an update. This should only be invoked when it is known with
-   * certainty that we are **not** in a DOM transaction.
-   *
-   * You may want to call this when you know that some deeper aspect of the
-   * component's state has changed but `setState` was not called.
-   *
-   * This will not invoke `shouldComponentUpdate`, but it will invoke
-   * `componentWillUpdate` and `componentDidUpdate`.
-   *
-   * @param {ReactClass} publicInstance The instance that should rerender.
-   * @param {?function} callback Called after component is updated.
-   * @param {?string} Name of the calling function in the public API.
-   * @internal
-   */
-  enqueueForceUpdate: function(publicInstance, callback, callerName) {
-    var internalInstance = getInternalInstanceReadyForUpdate(publicInstance);
-
-    if (!internalInstance) {
-      return;
-    }
-
-    callback = callback === undefined ? null : callback;
-    if (callback !== null) {
-      if (__DEV__) {
-        warnOnInvalidCallback(callback, callerName);
-      }
-      if (internalInstance._pendingCallbacks) {
-        internalInstance._pendingCallbacks.push(callback);
-      } else {
-        internalInstance._pendingCallbacks = [callback];
-      }
-    }
-
-    internalInstance._pendingForceUpdate = true;
-
-    enqueueUpdate(internalInstance);
-  },
-
-  /**
-   * Replaces all of the state. Always use this or `setState` to mutate state.
-   * You should treat `this.state` as immutable.
-   *
-   * There is no guarantee that `this.state` will be immediately updated, so
-   * accessing `this.state` after calling this method may return the old value.
-   *
-   * @param {ReactClass} publicInstance The instance that should rerender.
-   * @param {object} completeState Next state.
-   * @param {?function} callback Called after state is updated.
-   * @param {?string} Name of the calling function in the public API.
-   * @internal
-   */
-  enqueueReplaceState: function(
-    publicInstance,
-    completeState,
-    callback,
-    callerName,
-  ) {
-    var internalInstance = getInternalInstanceReadyForUpdate(publicInstance);
-
-    if (!internalInstance) {
-      return;
-    }
-
-    internalInstance._pendingStateQueue = [completeState];
-    internalInstance._pendingReplaceState = true;
-
-    callback = callback === undefined ? null : callback;
-    if (callback !== null) {
-      if (__DEV__) {
-        warnOnInvalidCallback(callback, callerName);
-      }
-      if (internalInstance._pendingCallbacks) {
-        internalInstance._pendingCallbacks.push(callback);
-      } else {
-        internalInstance._pendingCallbacks = [callback];
-      }
-    }
-
-    enqueueUpdate(internalInstance);
-  },
-
-  /**
-   * Sets a subset of the state. This only exists because _pendingState is
-   * internal. This provides a merging strategy that is not available to deep
-   * properties which is confusing. TODO: Expose pendingState or don't use it
-   * during the merge.
-   *
-   * @param {ReactClass} publicInstance The instance that should rerender.
-   * @param {object} partialState Next partial state to be merged with state.
-   * @param {?function} callback Called after state is updated.
-   * @param {?string} Name of the calling function in the public API.
-   * @internal
-   */
-  enqueueSetState: function(
-    publicInstance,
-    partialState,
-    callback,
-    callerName,
-  ) {
-    if (__DEV__) {
-      ReactInstrumentation.debugTool.onSetState();
-      warning(
-        partialState != null,
-        'setState(...): You passed an undefined or null state object; ' +
-          'instead, use forceUpdate().',
-      );
-    }
-
-    var internalInstance = getInternalInstanceReadyForUpdate(publicInstance);
-
-    if (!internalInstance) {
-      return;
-    }
-
-    var queue =
-      internalInstance._pendingStateQueue ||
-      (internalInstance._pendingStateQueue = []);
-    queue.push(partialState);
-
-    callback = callback === undefined ? null : callback;
-    if (callback !== null) {
-      if (__DEV__) {
-        warnOnInvalidCallback(callback, callerName);
-      }
-      if (internalInstance._pendingCallbacks) {
-        internalInstance._pendingCallbacks.push(callback);
-      } else {
-        internalInstance._pendingCallbacks = [callback];
-      }
-    }
-
-    enqueueUpdate(internalInstance);
-  },
-
-  enqueueElementInternal: function(internalInstance, nextElement, nextContext) {
-    internalInstance._pendingElement = nextElement;
-    // TODO: introduce _pendingContext instead of setting it directly.
-    internalInstance._context = nextContext;
-    enqueueUpdate(internalInstance);
-  },
-};
-
-module.exports = ReactUpdateQueue;
diff --git a/src/renderers/shared/stack/reconciler/ReactUpdates.js b/src/renderers/shared/stack/reconciler/ReactUpdates.js
deleted file mode 100644
index 73637000a2a..00000000000
--- a/src/renderers/shared/stack/reconciler/ReactUpdates.js
+++ /dev/null
@@ -1,222 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactUpdates
- */
-
-'use strict';
-
-var PooledClass = require('PooledClass');
-var ReactReconciler = require('ReactReconciler');
-var Transaction = require('Transaction');
-
-var invariant = require('fbjs/lib/invariant');
-
-var dirtyComponents = [];
-var updateBatchNumber = 0;
-
-var batchingStrategy = null;
-
-function ensureInjected() {
-  invariant(
-    ReactUpdates.ReactReconcileTransaction && batchingStrategy,
-    'ReactUpdates: must inject a reconcile transaction class and batching ' +
-      'strategy',
-  );
-}
-
-var NESTED_UPDATES = {
-  initialize: function() {
-    this.dirtyComponentsLength = dirtyComponents.length;
-  },
-  close: function() {
-    if (this.dirtyComponentsLength !== dirtyComponents.length) {
-      // Additional updates were enqueued by componentDidUpdate handlers or
-      // similar; before our own UPDATE_QUEUEING wrapper closes, we want to run
-      // these new updates so that if A's componentDidUpdate calls setState on
-      // B, B will update before the callback A's updater provided when calling
-      // setState.
-      dirtyComponents.splice(0, this.dirtyComponentsLength);
-      flushBatchedUpdates();
-    } else {
-      dirtyComponents.length = 0;
-    }
-  },
-};
-
-var TRANSACTION_WRAPPERS = [NESTED_UPDATES];
-
-function ReactUpdatesFlushTransaction() {
-  this.reinitializeTransaction();
-  this.dirtyComponentsLength = null;
-  this.reconcileTransaction = ReactUpdates.ReactReconcileTransaction.getPooled(
-    /* useCreateElement */ true,
-  );
-}
-
-Object.assign(ReactUpdatesFlushTransaction.prototype, Transaction, {
-  getTransactionWrappers: function() {
-    return TRANSACTION_WRAPPERS;
-  },
-
-  destructor: function() {
-    this.dirtyComponentsLength = null;
-    ReactUpdates.ReactReconcileTransaction.release(this.reconcileTransaction);
-    this.reconcileTransaction = null;
-  },
-
-  perform: function(method, scope, a) {
-    // Essentially calls `this.reconcileTransaction.perform(method, scope, a)`
-    // with this transaction's wrappers around it.
-    return Transaction.perform.call(
-      this,
-      this.reconcileTransaction.perform,
-      this.reconcileTransaction,
-      method,
-      scope,
-      a,
-    );
-  },
-});
-
-PooledClass.addPoolingTo(ReactUpdatesFlushTransaction);
-
-function batchedUpdates(callback, a, b, c, d, e) {
-  ensureInjected();
-  return batchingStrategy.batchedUpdates(callback, a, b, c, d, e);
-}
-
-/**
- * Array comparator for ReactComponents by mount ordering.
- *
- * @param {ReactComponent} c1 first component you're comparing
- * @param {ReactComponent} c2 second component you're comparing
- * @return {number} Return value usable by Array.prototype.sort().
- */
-function mountOrderComparator(c1, c2) {
-  return c1._mountOrder - c2._mountOrder;
-}
-
-function runBatchedUpdates(transaction) {
-  var len = transaction.dirtyComponentsLength;
-  invariant(
-    len === dirtyComponents.length,
-    "Expected flush transaction's stored dirty-components length (%s) to " +
-      'match dirty-components array length (%s).',
-    len,
-    dirtyComponents.length,
-  );
-
-  // Since reconciling a component higher in the owner hierarchy usually (not
-  // always -- see shouldComponentUpdate()) will reconcile children, reconcile
-  // them before their children by sorting the array.
-  dirtyComponents.sort(mountOrderComparator);
-
-  // Any updates enqueued while reconciling must be performed after this entire
-  // batch. Otherwise, if dirtyComponents is [A, B] where A has children B and
-  // C, B could update twice in a single batch if C's render enqueues an update
-  // to B (since B would have already updated, we should skip it, and the only
-  // way we can know to do so is by checking the batch counter).
-  updateBatchNumber++;
-
-  for (var i = 0; i < len; i++) {
-    // If a component is unmounted before pending changes apply, it will still
-    // be here, but we assume that it has cleared its _pendingCallbacks and
-    // that performUpdateIfNecessary is a noop.
-    var component = dirtyComponents[i];
-
-    ReactReconciler.performUpdateIfNecessary(
-      component,
-      transaction.reconcileTransaction,
-      updateBatchNumber,
-    );
-  }
-}
-
-var flushBatchedUpdates = function() {
-  // ReactUpdatesFlushTransaction's wrappers will clear the dirtyComponents
-  // array and perform any updates enqueued by mount-ready handlers (i.e.,
-  // componentDidUpdate) but we need to check here too in order to catch
-  // updates enqueued by setState callbacks.
-  while (dirtyComponents.length) {
-    var transaction = ReactUpdatesFlushTransaction.getPooled();
-    transaction.perform(runBatchedUpdates, null, transaction);
-    ReactUpdatesFlushTransaction.release(transaction);
-  }
-};
-
-/**
- * Mark a component as needing a rerender, adding an optional callback to a
- * list of functions which will be executed once the rerender occurs.
- */
-function enqueueUpdate(component) {
-  ensureInjected();
-
-  // Various parts of our code (such as ReactCompositeComponent's
-  // _renderValidatedComponent) assume that calls to render aren't nested;
-  // verify that that's the case. (This is called by each top-level update
-  // function, like setState, forceUpdate, etc.; creation and
-  // destruction of top-level components is guarded in ReactMount.)
-
-  if (!batchingStrategy.isBatchingUpdates) {
-    batchingStrategy.batchedUpdates(enqueueUpdate, component);
-    return;
-  }
-
-  dirtyComponents.push(component);
-  if (component._updateBatchNumber == null) {
-    component._updateBatchNumber = updateBatchNumber + 1;
-  }
-}
-
-var ReactUpdatesInjection = {
-  injectReconcileTransaction: function(ReconcileTransaction) {
-    invariant(
-      ReconcileTransaction,
-      'ReactUpdates: must provide a reconcile transaction class',
-    );
-    ReactUpdates.ReactReconcileTransaction = ReconcileTransaction;
-  },
-
-  injectBatchingStrategy: function(_batchingStrategy) {
-    invariant(
-      _batchingStrategy,
-      'ReactUpdates: must provide a batching strategy',
-    );
-    invariant(
-      typeof _batchingStrategy.batchedUpdates === 'function',
-      'ReactUpdates: must provide a batchedUpdates() function',
-    );
-    invariant(
-      typeof _batchingStrategy.isBatchingUpdates === 'boolean',
-      'ReactUpdates: must provide an isBatchingUpdates boolean attribute',
-    );
-    batchingStrategy = _batchingStrategy;
-  },
-
-  getBatchingStrategy: function() {
-    return batchingStrategy;
-  },
-};
-
-var ReactUpdates = {
-  /**
-   * React references `ReactReconcileTransaction` using this property in order
-   * to allow dependency injection.
-   *
-   * @internal
-   */
-  ReactReconcileTransaction: null,
-
-  batchedUpdates: batchedUpdates,
-  enqueueUpdate: enqueueUpdate,
-  flushBatchedUpdates: flushBatchedUpdates,
-  injection: ReactUpdatesInjection,
-};
-
-module.exports = ReactUpdates;
diff --git a/src/renderers/shared/stack/reconciler/Transaction.js b/src/renderers/shared/stack/reconciler/Transaction.js
deleted file mode 100644
index ee45da1b78a..00000000000
--- a/src/renderers/shared/stack/reconciler/Transaction.js
+++ /dev/null
@@ -1,243 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule Transaction
- * @flow
- */
-
-'use strict';
-
-var invariant = require('fbjs/lib/invariant');
-
-var OBSERVED_ERROR = {};
-
-/**
- * `Transaction` creates a black box that is able to wrap any method such that
- * certain invariants are maintained before and after the method is invoked
- * (Even if an exception is thrown while invoking the wrapped method). Whoever
- * instantiates a transaction can provide enforcers of the invariants at
- * creation time. The `Transaction` class itself will supply one additional
- * automatic invariant for you - the invariant that any transaction instance
- * should not be run while it is already being run. You would typically create a
- * single instance of a `Transaction` for reuse multiple times, that potentially
- * is used to wrap several different methods. Wrappers are extremely simple -
- * they only require implementing two methods.
- *
- * <pre>
- *                       wrappers (injected at creation time)
- *                                      +        +
- *                                      |        |
- *                    +-----------------|--------|--------------+
- *                    |                 v        |              |
- *                    |      +---------------+   |              |
- *                    |   +--|    wrapper1   |---|----+         |
- *                    |   |  +---------------+   v    |         |
- *                    |   |          +-------------+  |         |
- *                    |   |     +----|   wrapper2  |--------+   |
- *                    |   |     |    +-------------+  |     |   |
- *                    |   |     |                     |     |   |
- *                    |   v     v                     v     v   | wrapper
- *                    | +---+ +---+   +---------+   +---+ +---+ | invariants
- * perform(anyMethod) | |   | |   |   |         |   |   | |   | | maintained
- * +----------------->|-|---|-|---|-->|anyMethod|---|---|-|---|-|-------->
- *                    | |   | |   |   |         |   |   | |   | |
- *                    | |   | |   |   |         |   |   | |   | |
- *                    | |   | |   |   |         |   |   | |   | |
- *                    | +---+ +---+   +---------+   +---+ +---+ |
- *                    |  initialize                    close    |
- *                    +-----------------------------------------+
- * </pre>
- *
- * Use cases:
- * - Preserving the input selection ranges before/after reconciliation.
- *   Restoring selection even in the event of an unexpected error.
- * - Deactivating events while rearranging the DOM, preventing blurs/focuses,
- *   while guaranteeing that afterwards, the event system is reactivated.
- * - Flushing a queue of collected DOM mutations to the main UI thread after a
- *   reconciliation takes place in a worker thread.
- * - Invoking any collected `componentDidUpdate` callbacks after rendering new
- *   content.
- * - (Future use case): Wrapping particular flushes of the `ReactWorker` queue
- *   to preserve the `scrollTop` (an automatic scroll aware DOM).
- * - (Future use case): Layout calculations before and after DOM updates.
- *
- * Transactional plugin API:
- * - A module that has an `initialize` method that returns any precomputation.
- * - and a `close` method that accepts the precomputation. `close` is invoked
- *   when the wrapped process is completed, or has failed.
- *
- * @param {Array<TransactionalWrapper>} transactionWrapper Wrapper modules
- * that implement `initialize` and `close`.
- * @return {Transaction} Single transaction for reuse in thread.
- *
- * @class Transaction
- */
-var TransactionImpl = {
-  /**
-   * Sets up this instance so that it is prepared for collecting metrics. Does
-   * so such that this setup method may be used on an instance that is already
-   * initialized, in a way that does not consume additional memory upon reuse.
-   * That can be useful if you decide to make your subclass of this mixin a
-   * "PooledClass".
-   */
-  reinitializeTransaction: function(): void {
-    this.transactionWrappers = this.getTransactionWrappers();
-    if (this.wrapperInitData) {
-      this.wrapperInitData.length = 0;
-    } else {
-      this.wrapperInitData = [];
-    }
-    this._isInTransaction = false;
-  },
-
-  _isInTransaction: false,
-
-  /**
-   * @abstract
-   * @return {Array<TransactionWrapper>} Array of transaction wrappers.
-   */
-  getTransactionWrappers: null,
-
-  isInTransaction: function(): boolean {
-    return !!this._isInTransaction;
-  },
-
-  /**
-   * Executes the function within a safety window. Use this for the top level
-   * methods that result in large amounts of computation/mutations that would
-   * need to be safety checked. The optional arguments helps prevent the need
-   * to bind in many cases.
-   *
-   * @param {function} method Member of scope to call.
-   * @param {Object} scope Scope to invoke from.
-   * @param {Object?=} a Argument to pass to the method.
-   * @param {Object?=} b Argument to pass to the method.
-   * @param {Object?=} c Argument to pass to the method.
-   * @param {Object?=} d Argument to pass to the method.
-   * @param {Object?=} e Argument to pass to the method.
-   * @param {Object?=} f Argument to pass to the method.
-   *
-   * @return {*} Return value from `method`.
-   */
-  perform: function<
-    A,
-    B,
-    C,
-    D,
-    E,
-    F,
-    G,
-    T: (a: A, b: B, c: C, d: D, e: E, f: F) => G
-  >(method: T, scope: any, a: A, b: B, c: C, d: D, e: E, f: F): G {
-    invariant(
-      !this.isInTransaction(),
-      'Transaction.perform(...): Cannot initialize a transaction when there ' +
-        'is already an outstanding transaction.',
-    );
-    var errorThrown;
-    var ret;
-    try {
-      this._isInTransaction = true;
-      // Catching errors makes debugging more difficult, so we start with
-      // errorThrown set to true before setting it to false after calling
-      // close -- if it's still set to true in the finally block, it means
-      // one of these calls threw.
-      errorThrown = true;
-      this.initializeAll(0);
-      ret = method.call(scope, a, b, c, d, e, f);
-      errorThrown = false;
-    } finally {
-      try {
-        if (errorThrown) {
-          // If `method` throws, prefer to show that stack trace over any thrown
-          // by invoking `closeAll`.
-          try {
-            this.closeAll(0);
-          } catch (err) {}
-        } else {
-          // Since `method` didn't throw, we don't want to silence the exception
-          // here.
-          this.closeAll(0);
-        }
-      } finally {
-        this._isInTransaction = false;
-      }
-    }
-    return ret;
-  },
-
-  initializeAll: function(startIndex: number): void {
-    var transactionWrappers = this.transactionWrappers;
-    for (var i = startIndex; i < transactionWrappers.length; i++) {
-      var wrapper = transactionWrappers[i];
-      try {
-        // Catching errors makes debugging more difficult, so we start with the
-        // OBSERVED_ERROR state before overwriting it with the real return value
-        // of initialize -- if it's still set to OBSERVED_ERROR in the finally
-        // block, it means wrapper.initialize threw.
-        this.wrapperInitData[i] = OBSERVED_ERROR;
-        this.wrapperInitData[i] = wrapper.initialize
-          ? wrapper.initialize.call(this)
-          : null;
-      } finally {
-        if (this.wrapperInitData[i] === OBSERVED_ERROR) {
-          // The initializer for wrapper i threw an error; initialize the
-          // remaining wrappers but silence any exceptions from them to ensure
-          // that the first error is the one to bubble up.
-          try {
-            this.initializeAll(i + 1);
-          } catch (err) {}
-        }
-      }
-    }
-  },
-
-  /**
-   * Invokes each of `this.transactionWrappers.close[i]` functions, passing into
-   * them the respective return values of `this.transactionWrappers.init[i]`
-   * (`close`rs that correspond to initializers that failed will not be
-   * invoked).
-   */
-  closeAll: function(startIndex: number): void {
-    invariant(
-      this.isInTransaction(),
-      'Transaction.closeAll(): Cannot close transaction when none are open.',
-    );
-    var transactionWrappers = this.transactionWrappers;
-    for (var i = startIndex; i < transactionWrappers.length; i++) {
-      var wrapper = transactionWrappers[i];
-      var initData = this.wrapperInitData[i];
-      var errorThrown;
-      try {
-        // Catching errors makes debugging more difficult, so we start with
-        // errorThrown set to true before setting it to false after calling
-        // close -- if it's still set to true in the finally block, it means
-        // wrapper.close threw.
-        errorThrown = true;
-        if (initData !== OBSERVED_ERROR && wrapper.close) {
-          wrapper.close.call(this, initData);
-        }
-        errorThrown = false;
-      } finally {
-        if (errorThrown) {
-          // The closer for wrapper i threw an error; close the remaining
-          // wrappers but silence any exceptions from them to ensure that the
-          // first error is the one to bubble up.
-          try {
-            this.closeAll(i + 1);
-          } catch (e) {}
-        }
-      }
-    }
-    this.wrapperInitData.length = 0;
-  },
-};
-
-export type Transaction = typeof TransactionImpl;
-
-module.exports = TransactionImpl;
diff --git a/src/renderers/shared/stack/reconciler/__tests__/Transaction-test.js b/src/renderers/shared/stack/reconciler/__tests__/Transaction-test.js
deleted file mode 100644
index 00d0c2d29b1..00000000000
--- a/src/renderers/shared/stack/reconciler/__tests__/Transaction-test.js
+++ /dev/null
@@ -1,308 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @emails react-core
- */
-
-'use strict';
-
-var Transaction;
-
-var INIT_ERRORED = 'initErrored'; // Just a dummy value to check for.
-describe('Transaction', () => {
-  beforeEach(() => {
-    jest.resetModules();
-    Transaction = require('Transaction');
-  });
-
-  /**
-   * We should not invoke closers for inits that failed. We should pass init
-   * return values to closers when those inits are successful. We should not
-   * invoke the actual method when any of the initializers fail.
-   */
-  it('should invoke closers with/only-with init returns', () => {
-    var throwInInit = function() {
-      throw new Error('close[0] should receive Transaction.OBSERVED_ERROR');
-    };
-
-    var performSideEffect;
-    var dontPerformThis = function() {
-      performSideEffect = 'This should never be set to this';
-    };
-
-    /**
-     * New test Transaction subclass.
-     */
-    var TestTransaction = function() {
-      this.reinitializeTransaction();
-      this.firstCloseParam = INIT_ERRORED; // WON'T be set to something else
-      this.secondCloseParam = INIT_ERRORED; // WILL be set to something else
-      this.lastCloseParam = INIT_ERRORED; // WON'T be set to something else
-    };
-    Object.assign(TestTransaction.prototype, Transaction);
-    TestTransaction.prototype.getTransactionWrappers = function() {
-      return [
-        {
-          initialize: throwInInit,
-          close: function(initResult) {
-            this.firstCloseParam = initResult;
-          },
-        },
-        {
-          initialize: function() {
-            return 'asdf';
-          },
-          close: function(initResult) {
-            this.secondCloseParam = initResult;
-          },
-        },
-        {
-          initialize: throwInInit,
-          close: function(initResult) {
-            this.lastCloseParam = initResult;
-          },
-        },
-      ];
-    };
-
-    var transaction = new TestTransaction();
-
-    expect(function() {
-      transaction.perform(dontPerformThis);
-    }).toThrow();
-
-    expect(performSideEffect).toBe(undefined);
-    expect(transaction.firstCloseParam).toBe(INIT_ERRORED);
-    expect(transaction.secondCloseParam).toBe('asdf');
-    expect(transaction.lastCloseParam).toBe(INIT_ERRORED);
-    expect(transaction.isInTransaction()).toBe(false);
-  });
-
-  it('should invoke closers and wrapped method when inits success', () => {
-    var performSideEffect;
-    /**
-     * New test Transaction subclass.
-     */
-    var TestTransaction = function() {
-      this.reinitializeTransaction();
-      this.firstCloseParam = INIT_ERRORED; // WILL be set to something else
-      this.secondCloseParam = INIT_ERRORED; // WILL be set to something else
-      this.lastCloseParam = INIT_ERRORED; // WILL be set to something else
-    };
-    Object.assign(TestTransaction.prototype, Transaction);
-    TestTransaction.prototype.getTransactionWrappers = function() {
-      return [
-        {
-          initialize: function() {
-            return 'firstResult';
-          },
-          close: function(initResult) {
-            this.firstCloseParam = initResult;
-          },
-        },
-        {
-          initialize: function() {
-            return 'secondResult';
-          },
-          close: function(initResult) {
-            this.secondCloseParam = initResult;
-          },
-        },
-        {
-          initialize: function() {
-            return 'thirdResult';
-          },
-          close: function(initResult) {
-            this.lastCloseParam = initResult;
-          },
-        },
-      ];
-    };
-
-    var transaction = new TestTransaction();
-
-    transaction.perform(function() {
-      performSideEffect = 'SIDE_EFFECT';
-    });
-
-    expect(performSideEffect).toBe('SIDE_EFFECT');
-    expect(transaction.firstCloseParam).toBe('firstResult');
-    expect(transaction.secondCloseParam).toBe('secondResult');
-    expect(transaction.lastCloseParam).toBe('thirdResult');
-    expect(transaction.isInTransaction()).toBe(false);
-  });
-
-  /**
-   * When the operation throws, the transaction should throw, but all of the
-   * error-free closers should execute gracefully without issue. If a closer
-   * throws an error, the transaction should prefer to throw the error
-   * encountered earlier in the operation.
-   */
-  it('should throw when wrapped operation throws', () => {
-    var performSideEffect;
-    /**
-     * New test Transaction subclass.
-     */
-    var TestTransaction = function() {
-      this.reinitializeTransaction();
-      this.firstCloseParam = INIT_ERRORED; // WILL be set to something else
-      this.secondCloseParam = INIT_ERRORED; // WILL be set to something else
-      this.lastCloseParam = INIT_ERRORED; // WILL be set to something else
-    };
-    Object.assign(TestTransaction.prototype, Transaction);
-    // Now, none of the close/inits throw, but the operation we wrap will throw.
-    TestTransaction.prototype.getTransactionWrappers = function() {
-      return [
-        {
-          initialize: function() {
-            return 'firstResult';
-          },
-          close: function(initResult) {
-            this.firstCloseParam = initResult;
-          },
-        },
-        {
-          initialize: function() {
-            return 'secondResult';
-          },
-          close: function(initResult) {
-            this.secondCloseParam = initResult;
-          },
-        },
-        {
-          initialize: function() {
-            return 'thirdResult';
-          },
-          close: function(initResult) {
-            this.lastCloseParam = initResult;
-          },
-        },
-        {
-          initialize: function() {
-            return 'fourthResult';
-          },
-          close: function(initResult) {
-            throw new Error('The transaction should throw a TypeError.');
-          },
-        },
-      ];
-    };
-
-    var transaction = new TestTransaction();
-
-    expect(
-      (function() {
-        var isTypeError = false;
-        try {
-          transaction.perform(function() {
-            throw new TypeError('Thrown in main wrapped operation');
-          });
-        } catch (err) {
-          isTypeError = err instanceof TypeError;
-        }
-        return isTypeError;
-      })(),
-    ).toBe(true);
-
-    expect(performSideEffect).toBe(undefined);
-    expect(transaction.firstCloseParam).toBe('firstResult');
-    expect(transaction.secondCloseParam).toBe('secondResult');
-    expect(transaction.lastCloseParam).toBe('thirdResult');
-    expect(transaction.isInTransaction()).toBe(false);
-  });
-
-  it('should throw errors in transaction close', () => {
-    var TestTransaction = function() {
-      this.reinitializeTransaction();
-    };
-    Object.assign(TestTransaction.prototype, Transaction);
-    var exceptionMsg = 'This exception should throw.';
-    TestTransaction.prototype.getTransactionWrappers = function() {
-      return [
-        {
-          close: function(initResult) {
-            throw new Error(exceptionMsg);
-          },
-        },
-      ];
-    };
-
-    var transaction = new TestTransaction();
-    expect(function() {
-      transaction.perform(function() {});
-    }).toThrowError(exceptionMsg);
-    expect(transaction.isInTransaction()).toBe(false);
-  });
-
-  it('should allow nesting of transactions', () => {
-    var performSideEffect;
-    var nestedPerformSideEffect;
-    /**
-     * New test Transaction subclass.
-     */
-    var TestTransaction = function() {
-      this.reinitializeTransaction();
-      this.firstCloseParam = INIT_ERRORED; // WILL be set to something else
-    };
-    Object.assign(TestTransaction.prototype, Transaction);
-    TestTransaction.prototype.getTransactionWrappers = function() {
-      return [
-        {
-          initialize: function() {
-            return 'firstResult';
-          },
-          close: function(initResult) {
-            this.firstCloseParam = initResult;
-          },
-        },
-        {
-          initialize: function() {
-            this.nestedTransaction = new NestedTransaction();
-          },
-          close: function() {
-            // Test performing a transaction in another transaction's close()
-            this.nestedTransaction.perform(function() {
-              nestedPerformSideEffect = 'NESTED_SIDE_EFFECT';
-            });
-          },
-        },
-      ];
-    };
-
-    var NestedTransaction = function() {
-      this.reinitializeTransaction();
-    };
-    Object.assign(NestedTransaction.prototype, Transaction);
-    NestedTransaction.prototype.getTransactionWrappers = function() {
-      return [
-        {
-          initialize: function() {
-            this.hasInitializedNested = true;
-          },
-          close: function() {
-            this.hasClosedNested = true;
-          },
-        },
-      ];
-    };
-
-    var transaction = new TestTransaction();
-
-    transaction.perform(function() {
-      performSideEffect = 'SIDE_EFFECT';
-    });
-
-    expect(performSideEffect).toBe('SIDE_EFFECT');
-    expect(nestedPerformSideEffect).toBe('NESTED_SIDE_EFFECT');
-    expect(transaction.firstCloseParam).toBe('firstResult');
-    expect(transaction.isInTransaction()).toBe(false);
-    expect(transaction.nestedTransaction.hasClosedNested).toBe(true);
-    expect(transaction.nestedTransaction.hasInitializedNested).toBe(true);
-    expect(transaction.nestedTransaction.isInTransaction()).toBe(false);
-  });
-});
diff --git a/src/renderers/shared/stack/reconciler/flattenStackChildren.js b/src/renderers/shared/stack/reconciler/flattenStackChildren.js
deleted file mode 100644
index 699747d8392..00000000000
--- a/src/renderers/shared/stack/reconciler/flattenStackChildren.js
+++ /dev/null
@@ -1,111 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule flattenStackChildren
- * @flow
- */
-
-'use strict';
-
-var KeyEscapeUtils = require('KeyEscapeUtils');
-var traverseStackChildren = require('traverseStackChildren');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
-var ReactComponentTreeHook;
-
-if (
-  typeof process !== 'undefined' &&
-  process.env &&
-  process.env.NODE_ENV === 'test'
-) {
-  // Temporary hack.
-  // Inline requires don't work well with Jest:
-  // https://github.com/facebook/react/issues/7240
-  // Remove the inline requires when we don't need them anymore:
-  // https://github.com/facebook/react/pull/7178
-  ReactComponentTreeHook = require('ReactGlobalSharedState')
-    .ReactComponentTreeHook;
-}
-
-/**
- * @param {function} traverseContext Context passed through traversal.
- * @param {?ReactComponent} child React child component.
- * @param {!string} name String name of key path to child.
- * @param {number=} selfDebugID Optional debugID of the current internal instance.
- */
-function flattenSingleChildIntoContext(
-  traverseContext: mixed,
-  child: ReactElement<any>,
-  name: string,
-  selfDebugID?: number,
-): void {
-  // We found a component instance.
-  if (traverseContext && typeof traverseContext === 'object') {
-    const result = traverseContext;
-    const keyUnique = result[name] === undefined;
-    if (__DEV__) {
-      if (!ReactComponentTreeHook) {
-        ReactComponentTreeHook = require('ReactGlobalSharedState')
-          .ReactComponentTreeHook;
-      }
-      if (!keyUnique) {
-        warning(
-          false,
-          'flattenChildren(...): Encountered two children with the same key, ' +
-            '`%s`. ' +
-            'Keys should be unique so that components maintain their identity ' +
-            'across updates. Non-unique keys may cause children to be ' +
-            'duplicated and/or omitted — the behavior is unsupported and ' +
-            'could change in a future version.%s',
-          KeyEscapeUtils.unescapeInDev(name),
-          ReactComponentTreeHook.getStackAddendumByID(selfDebugID),
-        );
-      }
-    }
-    if (keyUnique && child != null) {
-      result[name] = child;
-    }
-  }
-}
-
-/**
- * Flattens children that are typically specified as `props.children`. Any null
- * children will not be included in the resulting object.
- * @return {!object} flattened children keyed by name.
- */
-function flattenStackChildren(
-  children: ReactElement<any>,
-  selfDebugID?: number,
-): ?{[name: string]: ReactElement<any>} {
-  if (children == null) {
-    return children;
-  }
-  var result = {};
-
-  if (__DEV__) {
-    traverseStackChildren(
-      children,
-      (traverseContext, child, name) =>
-        flattenSingleChildIntoContext(
-          traverseContext,
-          child,
-          name,
-          selfDebugID,
-        ),
-      result,
-    );
-  } else {
-    traverseStackChildren(children, flattenSingleChildIntoContext, result);
-  }
-  return result;
-}
-
-module.exports = flattenStackChildren;
diff --git a/src/renderers/shared/stack/reconciler/getHostComponentFromComposite.js b/src/renderers/shared/stack/reconciler/getHostComponentFromComposite.js
deleted file mode 100644
index 597caa50be8..00000000000
--- a/src/renderers/shared/stack/reconciler/getHostComponentFromComposite.js
+++ /dev/null
@@ -1,30 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule getHostComponentFromComposite
- */
-
-'use strict';
-
-var ReactNodeTypes = require('ReactNodeTypes');
-
-function getHostComponentFromComposite(inst) {
-  var type;
-
-  while ((type = inst._renderedNodeType) === ReactNodeTypes.COMPOSITE) {
-    inst = inst._renderedComponent;
-  }
-
-  if (type === ReactNodeTypes.HOST) {
-    return inst._renderedComponent;
-  } else if (type === ReactNodeTypes.EMPTY) {
-    return null;
-  }
-}
-
-module.exports = getHostComponentFromComposite;
diff --git a/src/renderers/shared/stack/reconciler/instantiateReactComponent.js b/src/renderers/shared/stack/reconciler/instantiateReactComponent.js
deleted file mode 100644
index d92f00f27b3..00000000000
--- a/src/renderers/shared/stack/reconciler/instantiateReactComponent.js
+++ /dev/null
@@ -1,158 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule instantiateReactComponent
- */
-
-'use strict';
-
-var ReactCompositeComponent = require('ReactCompositeComponent');
-var ReactEmptyComponent = require('ReactEmptyComponent');
-var ReactHostComponent = require('ReactHostComponent');
-
-var invariant = require('fbjs/lib/invariant');
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-}
-
-var nextDebugID = 1;
-
-// To avoid a cyclic dependency, we create the final class in this module
-var ReactCompositeComponentWrapper = function(element) {
-  this.construct(element);
-};
-
-function getDeclarationErrorAddendum(owner) {
-  if (owner) {
-    var name = owner.getName();
-    if (name) {
-      return '\n\nCheck the render method of `' + name + '`.';
-    }
-  }
-  return '';
-}
-
-/**
- * Check if the type reference is a known internal type. I.e. not a user
- * provided composite type.
- *
- * @param {function} type
- * @return {boolean} Returns true if this is a valid internal type.
- */
-function isInternalComponentType(type) {
-  return (
-    typeof type === 'function' &&
-    typeof type.prototype !== 'undefined' &&
-    typeof type.prototype.mountComponent === 'function' &&
-    typeof type.prototype.receiveComponent === 'function'
-  );
-}
-
-/**
- * Given a ReactNode, create an instance that will actually be mounted.
- *
- * @param {ReactNode} node
- * @param {boolean} shouldHaveDebugID
- * @return {object} A new instance of the element's constructor.
- * @protected
- */
-function instantiateReactComponent(node, shouldHaveDebugID) {
-  var instance;
-
-  if (node === null || node === false) {
-    instance = ReactEmptyComponent.create(instantiateReactComponent);
-  } else if (typeof node === 'object') {
-    var element = node;
-    var type = element.type;
-    if (typeof type !== 'function' && typeof type !== 'string') {
-      var info = '';
-      if (__DEV__) {
-        if (
-          type === undefined ||
-          (typeof type === 'object' &&
-            type !== null &&
-            Object.keys(type).length === 0)
-        ) {
-          info +=
-            ' You likely forgot to export your component from the file ' +
-            "it's defined in.";
-        }
-      }
-      info += getDeclarationErrorAddendum(element._owner);
-      invariant(
-        false,
-        'Element type is invalid: expected a string (for built-in components) ' +
-          'or a class/function (for composite components) but got: %s.%s',
-        type == null ? type : typeof type,
-        info,
-      );
-    }
-
-    // Special case string values
-    if (typeof element.type === 'string') {
-      instance = ReactHostComponent.createInternalComponent(element);
-    } else if (isInternalComponentType(element.type)) {
-      // This is temporarily available for custom components that are not string
-      // representations. I.e. ART. Once those are updated to use the string
-      // representation, we can drop this code path.
-      instance = new element.type(element);
-
-      // We renamed this. Allow the old name for compat. :(
-      if (!instance.getHostNode) {
-        instance.getHostNode = instance.getNativeNode;
-      }
-    } else {
-      instance = new ReactCompositeComponentWrapper(element);
-    }
-  } else if (typeof node === 'string' || typeof node === 'number') {
-    instance = ReactHostComponent.createInstanceForText(node);
-  } else {
-    invariant(false, 'Encountered invalid React node of type %s', typeof node);
-  }
-
-  if (__DEV__) {
-    warning(
-      typeof instance.mountComponent === 'function' &&
-        typeof instance.receiveComponent === 'function' &&
-        typeof instance.getHostNode === 'function' &&
-        typeof instance.unmountComponent === 'function',
-      'Only React Components can be mounted.',
-    );
-  }
-
-  // These two fields are used by the DOM and ART diffing algorithms
-  // respectively. Instead of using expandos on components, we should be
-  // storing the state needed by the diffing algorithms elsewhere.
-  instance._mountIndex = 0;
-  instance._mountImage = null;
-
-  if (__DEV__) {
-    instance._debugID = shouldHaveDebugID ? nextDebugID++ : 0;
-  }
-
-  // Internal instances should fully constructed at this point, so they should
-  // not get any new fields added to them at this point.
-  if (__DEV__) {
-    if (Object.preventExtensions) {
-      Object.preventExtensions(instance);
-    }
-  }
-
-  return instance;
-}
-
-Object.assign(
-  ReactCompositeComponentWrapper.prototype,
-  ReactCompositeComponent,
-  {
-    _instantiateReactComponent: instantiateReactComponent,
-  },
-);
-
-module.exports = instantiateReactComponent;
diff --git a/src/renderers/shared/stack/reconciler/traverseStackChildren.js b/src/renderers/shared/stack/reconciler/traverseStackChildren.js
deleted file mode 100644
index 765be094b5f..00000000000
--- a/src/renderers/shared/stack/reconciler/traverseStackChildren.js
+++ /dev/null
@@ -1,200 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule traverseStackChildren
- */
-
-'use strict';
-
-var invariant = require('fbjs/lib/invariant');
-var KeyEscapeUtils = require('KeyEscapeUtils');
-
-var ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
-var FAUX_ITERATOR_SYMBOL = '@@iterator'; // Before Symbol spec.
-// The Symbol used to tag the ReactElement type. If there is no native Symbol
-// nor polyfill, then a plain number is used for performance.
-var REACT_ELEMENT_TYPE =
-  (typeof Symbol === 'function' && Symbol.for && Symbol.for('react.element')) ||
-  0xeac7;
-
-if (__DEV__) {
-  var warning = require('fbjs/lib/warning');
-  var {
-    getCurrentStackAddendum,
-  } = require('ReactGlobalSharedState').ReactComponentTreeHook;
-}
-
-var SEPARATOR = '.';
-var SUBSEPARATOR = ':';
-
-/**
- * This is inlined from ReactElement since this file is shared between
- * isomorphic and renderers. We could extract this to a
- *
- */
-
-/**
- * TODO: Test that a single child and an array with one item have the same key
- * pattern.
- */
-
-var didWarnAboutMaps = false;
-
-/**
- * Generate a key string that identifies a component within a set.
- *
- * @param {*} component A component that could contain a manual key.
- * @param {number} index Index that is used if a manual key is not provided.
- * @return {string}
- */
-function getComponentKey(component, index) {
-  // Do some typechecking here since we call this blindly. We want to ensure
-  // that we don't block potential future ES APIs.
-  if (component && typeof component === 'object' && component.key != null) {
-    // Explicit key
-    return KeyEscapeUtils.escape(component.key);
-  }
-  // Implicit key determined by the index in the set
-  return index.toString(36);
-}
-
-/**
- * @param {?*} children Children tree container.
- * @param {!string} nameSoFar Name of the key path so far.
- * @param {!function} callback Callback to invoke with each child found.
- * @param {?*} traverseContext Used to pass information throughout the traversal
- * process.
- * @return {!number} The number of children in this subtree.
- */
-function traverseStackChildrenImpl(
-  children,
-  nameSoFar,
-  callback,
-  traverseContext,
-) {
-  var type = typeof children;
-
-  if (type === 'undefined' || type === 'boolean') {
-    // All of the above are perceived as null.
-    children = null;
-  }
-
-  if (
-    children === null ||
-    type === 'string' ||
-    type === 'number' ||
-    // The following is inlined from ReactElement. This means we can optimize
-    // some checks. React Fiber also inlines this logic for similar purposes.
-    (type === 'object' && children.$$typeof === REACT_ELEMENT_TYPE)
-  ) {
-    callback(
-      traverseContext,
-      children,
-      // If it's the only child, treat the name as if it was wrapped in an array
-      // so that it's consistent if the number of children grows.
-      nameSoFar === '' ? SEPARATOR + getComponentKey(children, 0) : nameSoFar,
-    );
-    return 1;
-  }
-
-  var child;
-  var nextName;
-  var subtreeCount = 0; // Count of children found in the current subtree.
-  var nextNamePrefix = nameSoFar === '' ? SEPARATOR : nameSoFar + SUBSEPARATOR;
-
-  if (Array.isArray(children)) {
-    for (var i = 0; i < children.length; i++) {
-      child = children[i];
-      nextName = nextNamePrefix + getComponentKey(child, i);
-      subtreeCount += traverseStackChildrenImpl(
-        child,
-        nextName,
-        callback,
-        traverseContext,
-      );
-    }
-  } else {
-    var iteratorFn =
-      (ITERATOR_SYMBOL && children[ITERATOR_SYMBOL]) ||
-      children[FAUX_ITERATOR_SYMBOL];
-    if (typeof iteratorFn === 'function') {
-      if (__DEV__) {
-        // Warn about using Maps as children
-        if (iteratorFn === children.entries) {
-          warning(
-            didWarnAboutMaps,
-            'Using Maps as children is unsupported and will likely yield ' +
-              'unexpected results. Convert it to a sequence/iterable of keyed ' +
-              'ReactElements instead.%s',
-            getCurrentStackAddendum(),
-          );
-          didWarnAboutMaps = true;
-        }
-      }
-
-      var iterator = iteratorFn.call(children);
-      var step;
-      var ii = 0;
-      while (!(step = iterator.next()).done) {
-        child = step.value;
-        nextName = nextNamePrefix + getComponentKey(child, ii++);
-        subtreeCount += traverseStackChildrenImpl(
-          child,
-          nextName,
-          callback,
-          traverseContext,
-        );
-      }
-    } else if (type === 'object') {
-      var addendum = '';
-      if (__DEV__) {
-        addendum =
-          ' If you meant to render a collection of children, use an array ' +
-          'instead.' +
-          getCurrentStackAddendum();
-      }
-      var childrenString = '' + children;
-      invariant(
-        false,
-        'Objects are not valid as a React child (found: %s).%s',
-        childrenString === '[object Object]'
-          ? 'object with keys {' + Object.keys(children).join(', ') + '}'
-          : childrenString,
-        addendum,
-      );
-    }
-  }
-
-  return subtreeCount;
-}
-
-/**
- * Traverses children that are typically specified as `props.children`, but
- * might also be specified through attributes:
- *
- * - `traverseStackChildren(this.props.children, ...)`
- * - `traverseStackChildren(this.props.leftPanelChildren, ...)`
- *
- * The `traverseContext` is an optional argument that is passed through the
- * entire traversal. It can be used to store accumulations or anything else that
- * the callback might find relevant.
- *
- * @param {?*} children Children tree object.
- * @param {!function} callback To invoke upon traversing each child.
- * @param {?*} traverseContext Context for traversal.
- * @return {!number} The number of children in this subtree.
- */
-function traverseStackChildren(children, callback, traverseContext) {
-  if (children == null) {
-    return 0;
-  }
-
-  return traverseStackChildrenImpl(children, '', callback, traverseContext);
-}
-
-module.exports = traverseStackChildren;
diff --git a/src/renderers/shared/utils/ReactErrorUtils.js b/src/renderers/shared/utils/ReactErrorUtils.js
index 4992464fbd9..4b54d207d1a 100644
--- a/src/renderers/shared/utils/ReactErrorUtils.js
+++ b/src/renderers/shared/utils/ReactErrorUtils.js
@@ -12,7 +12,11 @@
 
 'use strict';
 
-const invariant = require('fbjs/lib/invariant');
+import invariant from 'fbjs/lib/invariant';
+
+// TODO: this is a bit tricky to convert to function exports
+// because our internal version reads fields from this object.
+// This is non-obvious, and we should refactor it to pass those fields explicitly.
 
 const ReactErrorUtils = {
   // Used by Fiber to simulate a try-catch.
@@ -275,4 +279,4 @@ let rethrowCaughtError = function() {
   }
 };
 
-module.exports = ReactErrorUtils;
+export default ReactErrorUtils;
diff --git a/src/renderers/shared/utils/ReactFeatureFlags.js b/src/renderers/shared/utils/ReactFeatureFlags.js
index ae3a710354b..44b3a25040d 100644
--- a/src/renderers/shared/utils/ReactFeatureFlags.js
+++ b/src/renderers/shared/utils/ReactFeatureFlags.js
@@ -17,4 +17,4 @@ var ReactFeatureFlags = {
   enableAsyncSubtreeAPI: false,
 };
 
-module.exports = ReactFeatureFlags;
+export default ReactFeatureFlags;
diff --git a/src/renderers/shared/utils/__tests__/adler32-test.js b/src/renderers/shared/utils/__tests__/adler32-test.js
deleted file mode 100644
index ab6c7a0287c..00000000000
--- a/src/renderers/shared/utils/__tests__/adler32-test.js
+++ /dev/null
@@ -1,41 +0,0 @@
-/**
- * Copyright 2014-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @emails react-core
- */
-
-'use strict';
-
-var adler32 = require('adler32');
-
-describe('adler32', () => {
-  it('generates differing checksums', () => {
-    expect(adler32('foo')).not.toBe(adler32('bar'));
-  });
-
-  it('generates consistent checksums', () => {
-    expect(adler32('linux')).toBe(adler32('linux'));
-  });
-
-  it('is case sensitive', () => {
-    expect(adler32('a')).not.toBe(adler32('A'));
-  });
-
-  it("doesn't barf on large inputs", () => {
-    var str = '';
-    for (var i = 0; i < 100000; i++) {
-      str += 'This will be repeated to be very large indeed. ';
-    }
-    expect(adler32(str)).toBe(692898118);
-  });
-
-  it("doesn't barf on international inputs", () => {
-    var str = 'Linux 是一個真棒操作系統!';
-    expect(adler32(str)).toBe(-1183804097);
-  });
-});
diff --git a/src/renderers/shared/utils/accumulate.js b/src/renderers/shared/utils/accumulate.js
index ccb205298e8..8633693a993 100644
--- a/src/renderers/shared/utils/accumulate.js
+++ b/src/renderers/shared/utils/accumulate.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var invariant = require('fbjs/lib/invariant');
+import invariant from 'fbjs/lib/invariant';
 
 /**
  * Accumulates items that must not be null or undefined.
@@ -47,4 +47,4 @@ function accumulate<T>(
   return [current, next];
 }
 
-module.exports = accumulate;
+export default accumulate;
diff --git a/src/renderers/shared/utils/accumulateInto.js b/src/renderers/shared/utils/accumulateInto.js
index ae7e498278c..d28b215768d 100644
--- a/src/renderers/shared/utils/accumulateInto.js
+++ b/src/renderers/shared/utils/accumulateInto.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var invariant = require('fbjs/lib/invariant');
+import invariant from 'fbjs/lib/invariant';
 
 /**
  * Accumulates items that must not be null or undefined into the first one. This
@@ -59,4 +59,4 @@ function accumulateInto<T>(
   return [current, next];
 }
 
-module.exports = accumulateInto;
+export default accumulateInto;
diff --git a/src/renderers/shared/utils/adler32.js b/src/renderers/shared/utils/adler32.js
deleted file mode 100644
index 4013f2b26be..00000000000
--- a/src/renderers/shared/utils/adler32.js
+++ /dev/null
@@ -1,48 +0,0 @@
-/**
- * Copyright 2013-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule adler32
- * @flow
- */
-
-'use strict';
-
-var MOD = 65521;
-
-// adler32 is not cryptographically strong, and is only used to sanity check that
-// markup generated on the server matches the markup generated on the client.
-// This implementation (a modified version of the SheetJS version) has been optimized
-// for our use case, at the expense of conforming to the adler32 specification
-// for non-ascii inputs.
-function adler32(data: string): number {
-  var a = 1;
-  var b = 0;
-  var i = 0;
-  var l = data.length;
-  var m = l & ~0x3;
-  while (i < m) {
-    var n = Math.min(i + 4096, m);
-    for (; i < n; i += 4) {
-      b +=
-        (a += data.charCodeAt(i)) +
-        (a += data.charCodeAt(i + 1)) +
-        (a += data.charCodeAt(i + 2)) +
-        (a += data.charCodeAt(i + 3));
-    }
-    a %= MOD;
-    b %= MOD;
-  }
-  for (; i < l; i++) {
-    b += a += data.charCodeAt(i);
-  }
-  a %= MOD;
-  b %= MOD;
-  return a | (b << 16);
-}
-
-module.exports = adler32;
diff --git a/src/renderers/shared/utils/forEachAccumulated.js b/src/renderers/shared/utils/forEachAccumulated.js
index f7dc69f7ae7..9c35123c20d 100644
--- a/src/renderers/shared/utils/forEachAccumulated.js
+++ b/src/renderers/shared/utils/forEachAccumulated.js
@@ -33,4 +33,4 @@ function forEachAccumulated<T>(
   }
 }
 
-module.exports = forEachAccumulated;
+export default forEachAccumulated;
diff --git a/src/renderers/shared/utils/isTextInputElement.js b/src/renderers/shared/utils/isTextInputElement.js
index 633c19ce33a..cef5fae6141 100644
--- a/src/renderers/shared/utils/isTextInputElement.js
+++ b/src/renderers/shared/utils/isTextInputElement.js
@@ -47,4 +47,4 @@ function isTextInputElement(elem: ?HTMLElement): boolean {
   return false;
 }
 
-module.exports = isTextInputElement;
+export default isTextInputElement;
diff --git a/src/renderers/shared/utils/validateCallback.js b/src/renderers/shared/utils/validateCallback.js
index cf24bc8fd1a..0c585348f8c 100644
--- a/src/renderers/shared/utils/validateCallback.js
+++ b/src/renderers/shared/utils/validateCallback.js
@@ -14,7 +14,7 @@
 
 const invariant = require('fbjs/lib/invariant');
 
-function validateCallback(callback: ?Function) {
+export default function validateCallback(callback: ?Function) {
   invariant(
     !callback || typeof callback === 'function',
     'Invalid argument passed as callback. Expected a function. Instead ' +
@@ -22,5 +22,3 @@ function validateCallback(callback: ?Function) {
     callback,
   );
 }
-
-module.exports = validateCallback;
diff --git a/src/renderers/testing/ReactShallowRendererEntry.js b/src/renderers/testing/ReactShallowRendererEntry.js
index 0a1763d40e5..6e73afeafb5 100644
--- a/src/renderers/testing/ReactShallowRendererEntry.js
+++ b/src/renderers/testing/ReactShallowRendererEntry.js
@@ -12,14 +12,14 @@
 
 'use strict';
 
-const checkPropTypes = require('prop-types/checkPropTypes');
-const React = require('react');
+import checkPropTypes from 'prop-types/checkPropTypes';
+import React from 'react';
 
-const emptyObject = require('fbjs/lib/emptyObject');
-const invariant = require('fbjs/lib/invariant');
+import emptyObject from 'fbjs/lib/emptyObject';
+import invariant from 'fbjs/lib/invariant';
 
-const describeComponentFrame = require('describeComponentFrame');
-const getComponentName = require('getComponentName');
+import describeComponentFrame from 'describeComponentFrame';
+import getComponentName from 'getComponentName';
 
 class ReactShallowRenderer {
   static createRenderer = function() {
@@ -267,4 +267,6 @@ function shouldConstruct(Component) {
   return !!(Component.prototype && Component.prototype.isReactComponent);
 }
 
-module.exports = ReactShallowRenderer;
+// TODO: this fixes Rollup build but probably breaks Jest.
+// Need to figure something out.
+export default ReactShallowRenderer;
diff --git a/src/renderers/testing/ReactTestRendererFiberEntry.js b/src/renderers/testing/ReactTestRendererFiberEntry.js
index fff2175023e..0ef235a19fa 100644
--- a/src/renderers/testing/ReactTestRendererFiberEntry.js
+++ b/src/renderers/testing/ReactTestRendererFiberEntry.js
@@ -13,20 +13,19 @@
 
 'use strict';
 
-var ReactFiberReconciler = require('ReactFiberReconciler');
-var ReactFiberTreeReflection = require('ReactFiberTreeReflection');
-var ReactGenericBatching = require('ReactGenericBatching');
-var emptyObject = require('fbjs/lib/emptyObject');
-var ReactTypeOfWork = require('ReactTypeOfWork');
-var invariant = require('fbjs/lib/invariant');
-var {
+import ReactFiberReconciler from 'ReactFiberReconciler';
+import {findCurrentFiberUsingSlowPath} from 'ReactFiberTreeReflection';
+import {batchedUpdates} from 'ReactGenericBatching';
+import emptyObject from 'fbjs/lib/emptyObject';
+import {
   Fragment,
   FunctionalComponent,
   ClassComponent,
   HostComponent,
   HostText,
   HostRoot,
-} = ReactTypeOfWork;
+} from 'ReactTypeOfWork';
+import invariant from 'fbjs/lib/invariant';
 
 import type {Fiber} from 'ReactFiber';
 import type {FiberRoot} from 'ReactFiberRoot';
@@ -361,9 +360,7 @@ class ReactTestInstance {
 
   _currentFiber(): Fiber {
     // Throws if this component has been unmounted.
-    const fiber = ReactFiberTreeReflection.findCurrentFiberUsingSlowPath(
-      this._fiber,
-    );
+    const fiber = findCurrentFiberUsingSlowPath(this._fiber);
     invariant(
       fiber !== null,
       "Can't read from currently-mounting component. This error is likely " +
@@ -627,8 +624,10 @@ var ReactTestRendererFiber = {
   },
 
   /* eslint-disable camelcase */
-  unstable_batchedUpdates: ReactGenericBatching.batchedUpdates,
+  unstable_batchedUpdates: batchedUpdates,
   /* eslint-enable camelcase */
 };
 
-module.exports = ReactTestRendererFiber;
+// TODO: this fixes Rollup build but probably breaks Jest.
+// Need to figure something out.
+export default ReactTestRendererFiber;
diff --git a/src/shared/ReactFiberComponentTreeHook.js b/src/shared/ReactFiberComponentTreeHook.js
index 5f2163f6f0a..83b2676ad52 100644
--- a/src/shared/ReactFiberComponentTreeHook.js
+++ b/src/shared/ReactFiberComponentTreeHook.js
@@ -12,16 +12,14 @@
 
 'use strict';
 
-var ReactTypeOfWork = require('ReactTypeOfWork');
-var {
+import {
   IndeterminateComponent,
   FunctionalComponent,
   ClassComponent,
   HostComponent,
-} = ReactTypeOfWork;
-var describeComponentFrame = require('describeComponentFrame');
-var getComponentName = require('getComponentName');
-
+} from 'ReactTypeOfWork';
+import describeComponentFrame from 'describeComponentFrame';
+import getComponentName from 'getComponentName';
 import type {Fiber} from 'ReactFiber';
 
 function describeFiber(fiber: Fiber): string {
@@ -46,7 +44,9 @@ function describeFiber(fiber: Fiber): string {
 // This function can only be called with a work-in-progress fiber and
 // only during begin or complete phase. Do not call it under any other
 // circumstances.
-function getStackAddendumByWorkInProgressFiber(workInProgress: Fiber): string {
+export function getStackAddendumByWorkInProgressFiber(
+  workInProgress: Fiber,
+): string {
   var info = '';
   var node = workInProgress;
   do {
@@ -56,7 +56,3 @@ function getStackAddendumByWorkInProgressFiber(workInProgress: Fiber): string {
   } while (node);
   return info;
 }
-
-module.exports = {
-  getStackAddendumByWorkInProgressFiber,
-};
diff --git a/src/shared/ReactTypeOfWork.js b/src/shared/ReactTypeOfWork.js
index ef3585e1342..c9fc61f2256 100644
--- a/src/shared/ReactTypeOfWork.js
+++ b/src/shared/ReactTypeOfWork.js
@@ -14,16 +14,14 @@
 
 export type TypeOfWork = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10;
 
-module.exports = {
-  IndeterminateComponent: 0, // Before we know whether it is functional or class
-  FunctionalComponent: 1,
-  ClassComponent: 2,
-  HostRoot: 3, // Root of a host tree. Could be nested inside another node.
-  HostPortal: 4, // A subtree. Could be an entry point to a different renderer.
-  HostComponent: 5,
-  HostText: 6,
-  CoroutineComponent: 7,
-  CoroutineHandlerPhase: 8,
-  YieldComponent: 9,
-  Fragment: 10,
-};
+export const IndeterminateComponent = 0; // Before we know whether it is functional or class
+export const FunctionalComponent = 1;
+export const ClassComponent = 2;
+export const HostRoot = 3; // Root of a host tree. Could be nested inside another node.
+export const HostPortal = 4; // A subtree. Could be an entry point to a different renderer.
+export const HostComponent = 5;
+export const HostText = 6;
+export const CoroutineComponent = 7;
+export const CoroutineHandlerPhase = 8;
+export const YieldComponent = 9;
+export const Fragment = 10;
diff --git a/src/shared/describeComponentFrame.js b/src/shared/describeComponentFrame.js
index 67e8fbe3b92..7f46091e1f7 100644
--- a/src/shared/describeComponentFrame.js
+++ b/src/shared/describeComponentFrame.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-module.exports = function(
+export default function(
   name: null | string,
   source: any,
   ownerName: null | string,
@@ -28,4 +28,4 @@ module.exports = function(
           ')'
       : ownerName ? ' (created by ' + ownerName + ')' : '')
   );
-};
+}
diff --git a/src/shared/utils/getComponentName.js b/src/shared/utils/getComponentName.js
index b5360efc230..cabf3581472 100644
--- a/src/shared/utils/getComponentName.js
+++ b/src/shared/utils/getComponentName.js
@@ -12,29 +12,15 @@
 
 'use strict';
 
-import type {ReactInstance} from 'ReactInstanceType';
 import type {Fiber} from 'ReactFiber';
 
-function getComponentName(
-  instanceOrFiber: ReactInstance | Fiber,
-): string | null {
-  if (typeof instanceOrFiber.getName === 'function') {
-    // Stack reconciler
-    const instance = ((instanceOrFiber: any): ReactInstance);
-    return instance.getName();
+export default function getComponentName(fiber: Fiber): string | null {
+  const {type} = fiber;
+  if (typeof type === 'string') {
+    return type;
   }
-  if (typeof instanceOrFiber.tag === 'number') {
-    // Fiber reconciler
-    const fiber = ((instanceOrFiber: any): Fiber);
-    const {type} = fiber;
-    if (typeof type === 'string') {
-      return type;
-    }
-    if (typeof type === 'function') {
-      return type.displayName || type.name;
-    }
+  if (typeof type === 'function') {
+    return type.displayName || type.name;
   }
   return null;
 }
-
-module.exports = getComponentName;
diff --git a/src/shared/utils/lowPriorityWarning.js b/src/shared/utils/lowPriorityWarning.js
index 6de5fee71fb..1ea689c6f0e 100644
--- a/src/shared/utils/lowPriorityWarning.js
+++ b/src/shared/utils/lowPriorityWarning.js
@@ -25,7 +25,7 @@
  * same logic and follow the same code paths.
  */
 
-var lowPriorityWarning = function() {};
+let lowPriorityWarning = function() {};
 
 if (__DEV__) {
   const printWarning = function(format, ...args) {
@@ -55,4 +55,4 @@ if (__DEV__) {
   };
 }
 
-module.exports = lowPriorityWarning;
+export default lowPriorityWarning;
diff --git a/src/shared/utils/reactProdInvariant.js b/src/shared/utils/reactProdInvariant.js
index 9390b9eaa70..b67723e4d99 100644
--- a/src/shared/utils/reactProdInvariant.js
+++ b/src/shared/utils/reactProdInvariant.js
@@ -42,4 +42,5 @@ function reactProdInvariant(code: string): void {
   throw error;
 }
 
+// TODO: ESM?
 module.exports = reactProdInvariant;
diff --git a/src/test/ReactComponentTreeTestUtils.js b/src/test/ReactComponentTreeTestUtils.js
deleted file mode 100644
index 10dca25e19b..00000000000
--- a/src/test/ReactComponentTreeTestUtils.js
+++ /dev/null
@@ -1,107 +0,0 @@
-/**
- * Copyright 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule ReactComponentTreeTestUtils
- */
-
-'use strict';
-
-var ReactComponentTreeHook = require('ReactComponentTreeHook');
-
-function getRootDisplayNames() {
-  return ReactComponentTreeHook.getRootIDs().map(
-    ReactComponentTreeHook.getDisplayName,
-  );
-}
-
-function getRegisteredDisplayNames() {
-  return ReactComponentTreeHook.getRegisteredIDs().map(
-    ReactComponentTreeHook.getDisplayName,
-  );
-}
-
-function expectTree(rootID, expectedTree, parentPath) {
-  var displayName = ReactComponentTreeHook.getDisplayName(rootID);
-  var ownerID = ReactComponentTreeHook.getOwnerID(rootID);
-  var parentID = ReactComponentTreeHook.getParentID(rootID);
-  var childIDs = ReactComponentTreeHook.getChildIDs(rootID);
-  var text = ReactComponentTreeHook.getText(rootID);
-  var element = ReactComponentTreeHook.getElement(rootID);
-  var path = parentPath ? `${parentPath} > ${displayName}` : displayName;
-
-  function expectEqual(actual, expected, name) {
-    // Get Jasmine to print descriptive error messages.
-    // We pass path so that we know where the mismatch occurred.
-    expectDev({
-      path,
-      [name]: actual,
-    }).toEqual({
-      path,
-      [name]: expected,
-    });
-  }
-
-  if (expectedTree.parentDisplayName !== undefined) {
-    expectEqual(
-      ReactComponentTreeHook.getDisplayName(parentID),
-      expectedTree.parentDisplayName,
-      'parentDisplayName',
-    );
-  }
-  if (expectedTree.ownerDisplayName !== undefined) {
-    expectEqual(
-      ReactComponentTreeHook.getDisplayName(ownerID),
-      expectedTree.ownerDisplayName,
-      'ownerDisplayName',
-    );
-  }
-  if (expectedTree.parentID !== undefined) {
-    expectEqual(parentID, expectedTree.parentID, 'parentID');
-  }
-  if (expectedTree.text !== undefined) {
-    expectEqual(text, expectedTree.text, 'text');
-    expectEqual('' + element, expectedTree.text, 'element.toString()');
-  } else {
-    expectEqual(text, null, 'text');
-  }
-  if (expectedTree.element !== undefined) {
-    // TODO: Comparing elements makes tests run out of memory on errors.
-    // For now, compare just types.
-    expectEqual(
-      element && element.type,
-      expectedTree.element && expectedTree.element.type,
-      'element.type',
-    );
-  } else if (text == null) {
-    expectEqual(typeof element, 'object', 'typeof element');
-  }
-  if (expectedTree.children !== undefined) {
-    expectEqual(
-      childIDs.length,
-      expectedTree.children.length,
-      'children.length',
-    );
-    for (var i = 0; i < childIDs.length; i++) {
-      expectTree(
-        childIDs[i],
-        {parentID: rootID, ...expectedTree.children[i]},
-        path,
-      );
-    }
-  } else {
-    expectEqual(childIDs, [], 'childIDs');
-  }
-}
-
-var ReactComponentTreeTestUtils = {
-  expectTree,
-  getRootDisplayNames,
-  getRegisteredDisplayNames,
-};
-
-module.exports = ReactComponentTreeTestUtils;
diff --git a/src/test/getTestDocument.js b/src/test/getTestDocument.js
index ca946c7019c..b430e2956cb 100644
--- a/src/test/getTestDocument.js
+++ b/src/test/getTestDocument.js
@@ -22,4 +22,4 @@ function getTestDocument(markup) {
   return doc;
 }
 
-module.exports = getTestDocument;
+export default getTestDocument;