From da48ae0b8330aebb39c710df7340ce2ef902b39e Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Wed, 5 Apr 2017 20:26:58 +0900
Subject: [PATCH 01/21] Remove to use PooledClass for traverseAllChildren

---
 src/isomorphic/children/ReactChildren.js | 74 +++++-------------------
 1 file changed, 13 insertions(+), 61 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 206d9465755..cd77e958dde 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -11,40 +11,16 @@
 
 'use strict';
 
-var PooledClass = require('PooledClass');
 var ReactElement = require('ReactElement');
 
 var emptyFunction = require('fbjs/lib/emptyFunction');
 var traverseAllChildren = require('traverseAllChildren');
 
-var twoArgumentPooler = PooledClass.twoArgumentPooler;
-var fourArgumentPooler = PooledClass.fourArgumentPooler;
-
 var userProvidedKeyEscapeRegex = /\/+/g;
 function escapeUserProvidedKey(text) {
   return ('' + text).replace(userProvidedKeyEscapeRegex, '$&/');
 }
 
-/**
- * PooledClass representing the bookkeeping associated with performing a child
- * traversal. Allows avoiding binding callbacks.
- *
- * @constructor ForEachBookKeeping
- * @param {!function} forEachFunction Function to perform traversal with.
- * @param {?*} forEachContext Context to perform context with.
- */
-function ForEachBookKeeping(forEachFunction, forEachContext) {
-  this.func = forEachFunction;
-  this.context = forEachContext;
-  this.count = 0;
-}
-ForEachBookKeeping.prototype.destructor = function() {
-  this.func = null;
-  this.context = null;
-  this.count = 0;
-};
-PooledClass.addPoolingTo(ForEachBookKeeping, twoArgumentPooler);
-
 function forEachSingleChild(bookKeeping, child, name) {
   var {func, context} = bookKeeping;
   func.call(context, child, bookKeeping.count++);
@@ -66,39 +42,14 @@ function forEachChildren(children, forEachFunc, forEachContext) {
   if (children == null) {
     return children;
   }
-  var traverseContext = ForEachBookKeeping.getPooled(
-    forEachFunc,
-    forEachContext,
-  );
+  var traverseContext = {
+    func: forEachFunc,
+    context: forEachContext,
+    count: 0,
+  };
   traverseAllChildren(children, forEachSingleChild, traverseContext);
-  ForEachBookKeeping.release(traverseContext);
 }
 
-/**
- * PooledClass representing the bookkeeping associated with performing a child
- * mapping. Allows avoiding binding callbacks.
- *
- * @constructor MapBookKeeping
- * @param {!*} mapResult Object containing the ordered map of results.
- * @param {!function} mapFunction Function to perform mapping with.
- * @param {?*} mapContext Context to perform mapping with.
- */
-function MapBookKeeping(mapResult, keyPrefix, mapFunction, mapContext) {
-  this.result = mapResult;
-  this.keyPrefix = keyPrefix;
-  this.func = mapFunction;
-  this.context = mapContext;
-  this.count = 0;
-}
-MapBookKeeping.prototype.destructor = function() {
-  this.result = null;
-  this.keyPrefix = null;
-  this.func = null;
-  this.context = null;
-  this.count = 0;
-};
-PooledClass.addPoolingTo(MapBookKeeping, fourArgumentPooler);
-
 function mapSingleChildIntoContext(bookKeeping, child, childKey) {
   var {result, keyPrefix, func, context} = bookKeeping;
 
@@ -132,14 +83,15 @@ function mapIntoWithKeyPrefixInternal(children, array, prefix, func, context) {
   if (prefix != null) {
     escapedPrefix = escapeUserProvidedKey(prefix) + '/';
   }
-  var traverseContext = MapBookKeeping.getPooled(
-    array,
-    escapedPrefix,
-    func,
-    context,
-  );
+  var traverseContext = {
+    result: array,
+    keyPrefix: escapedPrefix,
+    func: func,
+    context: context,
+    count: 0,
+  };
+
   traverseAllChildren(children, mapSingleChildIntoContext, traverseContext);
-  MapBookKeeping.release(traverseContext);
 }
 
 /**

From efb71072129b2a9eff9eb4bc5c914d9c0b1abd0f Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Wed, 12 Apr 2017 18:34:08 +0900
Subject: [PATCH 02/21] move traverseAllChildren into ReactChildren

---
 src/isomorphic/children/ReactChildren.js | 168 ++++++++++++++++++++++-
 1 file changed, 164 insertions(+), 4 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index cd77e958dde..5c4786ee434 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -14,7 +14,161 @@
 var ReactElement = require('ReactElement');
 
 var emptyFunction = require('fbjs/lib/emptyFunction');
-var traverseAllChildren = require('traverseAllChildren');
+
+var ReactCurrentOwner = require('react/lib/ReactCurrentOwner');
+var REACT_ELEMENT_TYPE = require('ReactElementSymbol');
+
+var getIteratorFn = require('getIteratorFn');
+var invariant = require('fbjs/lib/invariant');
+var KeyEscapeUtils = require('KeyEscapeUtils');
+var warning = require('fbjs/lib/warning');
+
+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);
+}
+
+function traverseAllChildren(
+  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 += traverseAllChildren(
+        child,
+        nextName,
+        callback,
+        traverseContext,
+      );
+    }
+  } else {
+    var iteratorFn = getIteratorFn(children);
+    if (iteratorFn) {
+      if (__DEV__) {
+        // Warn about using Maps as children
+        if (iteratorFn === children.entries) {
+          let mapsAsChildrenAddendum = '';
+          if (ReactCurrentOwner.current) {
+            var mapsAsChildrenOwnerName = ReactCurrentOwner.current.getName();
+            if (mapsAsChildrenOwnerName) {
+              mapsAsChildrenAddendum = '\n\nCheck the render method of `' +
+                mapsAsChildrenOwnerName +
+                '`.';
+            }
+          }
+          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',
+            mapsAsChildrenAddendum,
+          );
+          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 += traverseAllChildren(
+          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.';
+        if (ReactCurrentOwner.current) {
+          var name = ReactCurrentOwner.current.getName();
+          if (name) {
+            addendum += '\n\nCheck the render method of `' + name + '`.';
+          }
+        }
+      }
+      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;
+}
 
 var userProvidedKeyEscapeRegex = /\/+/g;
 function escapeUserProvidedKey(text) {
@@ -47,7 +201,7 @@ function forEachChildren(children, forEachFunc, forEachContext) {
     context: forEachContext,
     count: 0,
   };
-  traverseAllChildren(children, forEachSingleChild, traverseContext);
+  traverseAllChildren(children, '', forEachSingleChild, traverseContext);
 }
 
 function mapSingleChildIntoContext(bookKeeping, child, childKey) {
@@ -79,6 +233,9 @@ function mapSingleChildIntoContext(bookKeeping, child, childKey) {
 }
 
 function mapIntoWithKeyPrefixInternal(children, array, prefix, func, context) {
+  if (children == null) {
+    return;
+  }
   var escapedPrefix = '';
   if (prefix != null) {
     escapedPrefix = escapeUserProvidedKey(prefix) + '/';
@@ -91,7 +248,7 @@ function mapIntoWithKeyPrefixInternal(children, array, prefix, func, context) {
     count: 0,
   };
 
-  traverseAllChildren(children, mapSingleChildIntoContext, traverseContext);
+  traverseAllChildren(children, '', mapSingleChildIntoContext, traverseContext);
 }
 
 /**
@@ -130,7 +287,10 @@ function forEachSingleChildDummy(traverseContext, child, name) {
  * @return {number} The number of children.
  */
 function countChildren(children, context) {
-  return traverseAllChildren(children, forEachSingleChildDummy, null);
+  if (children == null) {
+    return 0;
+  }
+  return traverseAllChildren(children, '', forEachSingleChildDummy, null);
 }
 
 /**

From d5b4b570523a463ba36c854a3be9a5964681458c Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Fri, 14 Apr 2017 17:06:04 +0900
Subject: [PATCH 03/21] Use mapChildren to forEach and toArray

---
 src/isomorphic/children/ReactChildren.js | 86 ++++++++++--------------
 1 file changed, 36 insertions(+), 50 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 5c4786ee434..ed1a34bcc23 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -175,35 +175,6 @@ function escapeUserProvidedKey(text) {
   return ('' + text).replace(userProvidedKeyEscapeRegex, '$&/');
 }
 
-function forEachSingleChild(bookKeeping, child, name) {
-  var {func, context} = bookKeeping;
-  func.call(context, child, bookKeeping.count++);
-}
-
-/**
- * Iterates through children that are typically specified as `props.children`.
- *
- * See https://facebook.github.io/react/docs/react-api.html#react.children.foreach
- *
- * The provided forEachFunc(child, index) will be called for each
- * leaf child.
- *
- * @param {?*} children Children tree container.
- * @param {function(*, int)} forEachFunc
- * @param {*} forEachContext Context for forEachContext.
- */
-function forEachChildren(children, forEachFunc, forEachContext) {
-  if (children == null) {
-    return children;
-  }
-  var traverseContext = {
-    func: forEachFunc,
-    context: forEachContext,
-    count: 0,
-  };
-  traverseAllChildren(children, '', forEachSingleChild, traverseContext);
-}
-
 function mapSingleChildIntoContext(bookKeeping, child, childKey) {
   var {result, keyPrefix, func, context} = bookKeeping;
 
@@ -269,12 +240,44 @@ function mapChildren(children, func, context) {
     return children;
   }
   var result = [];
-  mapIntoWithKeyPrefixInternal(children, result, null, func, context);
+  var traverseContext = {
+    result: result,
+    keyPrefix: '',
+    func: func,
+    context: context,
+    count: 0,
+  };
+  traverseAllChildren(children, '', mapSingleChildIntoContext, traverseContext);
   return result;
 }
 
-function forEachSingleChildDummy(traverseContext, child, name) {
-  return null;
+/**
+ * Iterates through children that are typically specified as `props.children`.
+ *
+ * See https://facebook.github.io/react/docs/react-api.html#react.children.foreach
+ *
+ * The provided forEachFunc(child, index) will be called for each
+ * leaf child.
+ *
+ * @param {?*} children Children tree container.
+ * @param {function(*, int)} forEachFunc
+ * @param {*} forEachContext Context for forEachContext.
+ */
+function forEachChildren(children, forEachFunc, forEachContext) {
+  mapChildren(children, forEachFunc, forEachContext);
+}
+
+/**
+ * Flatten a children object (typically specified as `props.children`) and
+ * return an array with appropriately re-keyed children.
+ *
+ * See https://facebook.github.io/react/docs/react-api.html#react.children.toarray
+ */
+function toArray(children) {
+  if (children == null) {
+    return [];
+  }
+  return mapChildren(children, emptyFunction.thatReturnsArgument, null);
 }
 
 /**
@@ -290,24 +293,7 @@ function countChildren(children, context) {
   if (children == null) {
     return 0;
   }
-  return traverseAllChildren(children, '', forEachSingleChildDummy, null);
-}
-
-/**
- * Flatten a children object (typically specified as `props.children`) and
- * return an array with appropriately re-keyed children.
- *
- * See https://facebook.github.io/react/docs/react-api.html#react.children.toarray
- */
-function toArray(children) {
-  var result = [];
-  mapIntoWithKeyPrefixInternal(
-    children,
-    result,
-    null,
-    emptyFunction.thatReturnsArgument,
-  );
-  return result;
+  return traverseAllChildren(children, '', emptyFunction.thatReturns, null);
 }
 
 var ReactChildren = {

From 437120d40d075d70f3fdf3254079c626cacce0e2 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Mon, 17 Apr 2017 17:17:34 +0900
Subject: [PATCH 04/21] Remove React.Children.mapIntoWithKeyPrefixInternal

---
 src/isomorphic/children/ReactChildren.js | 40 ++++++++----------------
 1 file changed, 13 insertions(+), 27 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index ed1a34bcc23..bbaf4a3b4a5 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -179,14 +179,20 @@ function mapSingleChildIntoContext(bookKeeping, child, childKey) {
   var {result, keyPrefix, func, context} = bookKeeping;
 
   var mappedChild = func.call(context, child, bookKeeping.count++);
+  if (mappedChild == null) {
+    return;
+  }
+
   if (Array.isArray(mappedChild)) {
-    mapIntoWithKeyPrefixInternal(
-      mappedChild,
-      result,
-      childKey,
-      emptyFunction.thatReturnsArgument,
-    );
-  } else if (mappedChild != null) {
+    var traverseContext = {
+      result: result,
+      keyPrefix: childKey != null ? escapeUserProvidedKey(childKey) + '/' : '',
+      func: emptyFunction.thatReturnsArgument,
+      context: null,
+      count: 0,
+    };
+    traverseAllChildren(mappedChild, '', mapSingleChildIntoContext, traverseContext);
+  } else {
     if (ReactElement.isValidElement(mappedChild)) {
       mappedChild = ReactElement.cloneAndReplaceKey(
         mappedChild,
@@ -203,25 +209,6 @@ function mapSingleChildIntoContext(bookKeeping, child, childKey) {
   }
 }
 
-function mapIntoWithKeyPrefixInternal(children, array, prefix, func, context) {
-  if (children == null) {
-    return;
-  }
-  var escapedPrefix = '';
-  if (prefix != null) {
-    escapedPrefix = escapeUserProvidedKey(prefix) + '/';
-  }
-  var traverseContext = {
-    result: array,
-    keyPrefix: escapedPrefix,
-    func: func,
-    context: context,
-    count: 0,
-  };
-
-  traverseAllChildren(children, '', mapSingleChildIntoContext, traverseContext);
-}
-
 /**
  * Maps children that are typically specified as `props.children`.
  *
@@ -299,7 +286,6 @@ function countChildren(children, context) {
 var ReactChildren = {
   forEach: forEachChildren,
   map: mapChildren,
-  mapIntoWithKeyPrefixInternal: mapIntoWithKeyPrefixInternal,
   count: countChildren,
   toArray: toArray,
 };

From a2bcddc44fe7fcbb4876c77c87cc36474105cc73 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Mon, 17 Apr 2017 17:19:05 +0900
Subject: [PATCH 05/21] Run prettier

---
 src/isomorphic/children/ReactChildren.js | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index bbaf4a3b4a5..fdf4a389e1b 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -57,12 +57,7 @@ function getComponentKey(component, index) {
   return index.toString(36);
 }
 
-function traverseAllChildren(
-  children,
-  nameSoFar,
-  callback,
-  traverseContext,
-) {
+function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
   var type = typeof children;
 
   if (type === 'undefined' || type === 'boolean') {
@@ -191,7 +186,12 @@ function mapSingleChildIntoContext(bookKeeping, child, childKey) {
       context: null,
       count: 0,
     };
-    traverseAllChildren(mappedChild, '', mapSingleChildIntoContext, traverseContext);
+    traverseAllChildren(
+      mappedChild,
+      '',
+      mapSingleChildIntoContext,
+      traverseContext,
+    );
   } else {
     if (ReactElement.isValidElement(mappedChild)) {
       mappedChild = ReactElement.cloneAndReplaceKey(

From e6060f61ac6ffcc65ba51b02329086e5b4bd5060 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Mon, 17 Apr 2017 18:09:46 +0900
Subject: [PATCH 06/21] Remove unnecessary arguments

---
 src/isomorphic/children/ReactChildren.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index fdf4a389e1b..244207516d0 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -264,7 +264,7 @@ function toArray(children) {
   if (children == null) {
     return [];
   }
-  return mapChildren(children, emptyFunction.thatReturnsArgument, null);
+  return mapChildren(children, emptyFunction.thatReturnsArgument);
 }
 
 /**
@@ -280,7 +280,7 @@ function countChildren(children, context) {
   if (children == null) {
     return 0;
   }
-  return traverseAllChildren(children, '', emptyFunction.thatReturns, null);
+  return traverseAllChildren(children, '', emptyFunction.thatReturns);
 }
 
 var ReactChildren = {

From ed041b4caca2d9f4a0213aa2bb05c48821be02bf Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Tue, 18 Apr 2017 10:23:57 +0900
Subject: [PATCH 07/21] Remove an unused argument from ReactChildren.count

---
 src/isomorphic/children/ReactChildren.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 244207516d0..1ccbf8e18af 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -276,7 +276,7 @@ function toArray(children) {
  * @param {?*} children Children tree container.
  * @return {number} The number of children.
  */
-function countChildren(children, context) {
+function countChildren(children) {
   if (children == null) {
     return 0;
   }

From 1ead8825f68bd7404e7426affc2942f7fadb6d1a Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Thu, 20 Apr 2017 18:40:51 +0900
Subject: [PATCH 08/21] Test for a single child and an array with one item

---
 src/isomorphic/children/ReactChildren.js                | 5 -----
 src/isomorphic/children/__tests__/ReactChildren-test.js | 4 ++--
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 1ccbf8e18af..a7f95134292 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -32,11 +32,6 @@ var SUBSEPARATOR = ':';
  *
  */
 
-/**
- * TODO: Test that a single child and an array with one item have the same key
- * pattern.
- */
-
 var didWarnAboutMaps = false;
 
 /**
diff --git a/src/isomorphic/children/__tests__/ReactChildren-test.js b/src/isomorphic/children/__tests__/ReactChildren-test.js
index 9d97007cd17..6a754be0a2e 100644
--- a/src/isomorphic/children/__tests__/ReactChildren-test.js
+++ b/src/isomorphic/children/__tests__/ReactChildren-test.js
@@ -60,7 +60,7 @@ describe('ReactChildren', () => {
       return kid;
     });
 
-    var simpleKid = <span />;
+    var simpleKid = <span key="simple" />;
     var instance = <div>{simpleKid}</div>;
     React.Children.forEach(instance.props.children, callback, context);
     expect(callback).toHaveBeenCalledWith(simpleKid, 0);
@@ -71,7 +71,7 @@ describe('ReactChildren', () => {
       context,
     );
     expect(callback).toHaveBeenCalledWith(simpleKid, 0);
-    expect(mappedChildren[0]).toEqual(<span key=".0" />);
+    expect(mappedChildren[0]).toEqual(<span key=".$simple" />);
   });
 
   it('should treat single child in array as expected', () => {

From ab49e3acc1b53a531fdcd218ede80f5addc9b189 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Fri, 21 Apr 2017 09:58:39 +0900
Subject: [PATCH 09/21] Add component stack to invalid-object-child error
 (cherry-pick #9415)

---
 src/isomorphic/children/ReactChildren.js | 27 ++++++++----------------
 1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index a7f95134292..7cd8356b397 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -15,7 +15,6 @@ var ReactElement = require('ReactElement');
 
 var emptyFunction = require('fbjs/lib/emptyFunction');
 
-var ReactCurrentOwner = require('react/lib/ReactCurrentOwner');
 var REACT_ELEMENT_TYPE = require('ReactElementSymbol');
 
 var getIteratorFn = require('getIteratorFn');
@@ -23,6 +22,12 @@ var invariant = require('fbjs/lib/invariant');
 var KeyEscapeUtils = require('KeyEscapeUtils');
 var warning = require('fbjs/lib/warning');
 
+if (__DEV__) {
+   var {
+     getCurrentStackAddendum,
+   } = require('ReactComponentTreeHook');
+}
+
 var SEPARATOR = '.';
 var SUBSEPARATOR = ':';
 
@@ -100,21 +105,12 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
       if (__DEV__) {
         // Warn about using Maps as children
         if (iteratorFn === children.entries) {
-          let mapsAsChildrenAddendum = '';
-          if (ReactCurrentOwner.current) {
-            var mapsAsChildrenOwnerName = ReactCurrentOwner.current.getName();
-            if (mapsAsChildrenOwnerName) {
-              mapsAsChildrenAddendum = '\n\nCheck the render method of `' +
-                mapsAsChildrenOwnerName +
-                '`.';
-            }
-          }
           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',
-            mapsAsChildrenAddendum,
+            getCurrentStackAddendum(),
           );
           didWarnAboutMaps = true;
         }
@@ -137,13 +133,8 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
       var addendum = '';
       if (__DEV__) {
         addendum = ' If you meant to render a collection of children, use an array ' +
-          'instead.';
-        if (ReactCurrentOwner.current) {
-          var name = ReactCurrentOwner.current.getName();
-          if (name) {
-            addendum += '\n\nCheck the render method of `' + name + '`.';
-          }
-        }
+          'instead.' +
+          getCurrentStackAddendum();
       }
       var childrenString = '' + children;
       invariant(

From 2e982b9d7617443237b3d29fc88cdb113f6b4ab3 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Fri, 21 Apr 2017 10:04:16 +0900
Subject: [PATCH 10/21] Add test for single child witout key

---
 .../children/__tests__/ReactChildren-test.js  | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/src/isomorphic/children/__tests__/ReactChildren-test.js b/src/isomorphic/children/__tests__/ReactChildren-test.js
index 6a754be0a2e..0f9eb06726e 100644
--- a/src/isomorphic/children/__tests__/ReactChildren-test.js
+++ b/src/isomorphic/children/__tests__/ReactChildren-test.js
@@ -28,6 +28,27 @@ describe('ReactChildren', () => {
     ReactTestUtils = require('react-dom/test-utils');
   });
 
+  it('should support single child without key', () => {
+    var context = {};
+    var callback = jasmine.createSpy().and.callFake(function(kid, index) {
+      expect(this).toBe(context);
+      return kid;
+    });
+
+    var simpleKid = <span />;
+    var instance = <div>{simpleKid}</div>;
+    React.Children.forEach(instance.props.children, callback, context);
+    expect(callback).toHaveBeenCalledWith(simpleKid, 0);
+    callback.calls.reset();
+    var mappedChildren = React.Children.map(
+      instance.props.children,
+      callback,
+      context,
+    );
+    expect(callback).toHaveBeenCalledWith(simpleKid, 0);
+    expect(mappedChildren[0]).toEqual(<span key=".0" />);
+  });
+
   it('should support identity for simple', () => {
     var context = {};
     var callback = jasmine.createSpy().and.callFake(function(kid, index) {

From 892dd52f0f8ca33fcd739081415ac6bbef756cbd Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Wed, 26 Apr 2017 12:27:54 +0900
Subject: [PATCH 11/21] Improve component type check in getComponentKey
 (cherry-pick #9464)

---
 src/isomorphic/children/ReactChildren.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 7cd8356b397..6eba0d7ee9e 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -49,7 +49,9 @@ var didWarnAboutMaps = false;
 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) {
+  if (
+    typeof component === 'object' && component !== null && component.key != null
+  ) {
     // Explicit key
     return KeyEscapeUtils.escape(component.key);
   }

From 1e5ab7c59c1a4ddab877f5a00696a37dac9f9f3f Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Mon, 8 May 2017 14:43:33 +0900
Subject: [PATCH 12/21] Add Flow types

---
 src/isomorphic/children/ReactChildren.js | 50 ++++++++++++++----------
 1 file changed, 29 insertions(+), 21 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 6eba0d7ee9e..e89d986a9ae 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -7,6 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule ReactChildren
+ * @flow
  */
 
 'use strict';
@@ -40,20 +41,20 @@ var SUBSEPARATOR = ':';
 var didWarnAboutMaps = false;
 
 /**
- * Generate a key string that identifies a component within a set.
+ * Generate a key string that identifies a ReactElement within a set.
  *
- * @param {*} component A component that could contain a manual key.
+ * @param {*} element A ReactElement 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) {
+function getReactElementKey(element: ?ReactElement, index) {
   // Do some typechecking here since we call this blindly. We want to ensure
   // that we don't block potential future ES APIs.
   if (
-    typeof component === 'object' && component !== null && component.key != null
+    typeof element === 'object' && element !== null && element.key != null
   ) {
     // Explicit key
-    return KeyEscapeUtils.escape(component.key);
+    return KeyEscapeUtils.escape(element.key);
   }
   // Implicit key determined by the index in the set
   return index.toString(36);
@@ -73,14 +74,14 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
     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.$$typeof === REACT_ELEMENT_TYPE)
+    (type === 'object' && (children: ReactElement).$$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,
+      nameSoFar === '' ? SEPARATOR + getReactElementKey(children, 0) : nameSoFar,
     );
     return 1;
   }
@@ -93,7 +94,7 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
   if (Array.isArray(children)) {
     for (var i = 0; i < children.length; i++) {
       child = children[i];
-      nextName = nextNamePrefix + getComponentKey(child, i);
+      nextName = nextNamePrefix + getReactElementKey(child, i);
       subtreeCount += traverseAllChildren(
         child,
         nextName,
@@ -106,7 +107,7 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
     if (iteratorFn) {
       if (__DEV__) {
         // Warn about using Maps as children
-        if (iteratorFn === children.entries) {
+        if (children != null && iteratorFn === children.entries) {
           warning(
             didWarnAboutMaps,
             'Using Maps as children is unsupported and will likely yield ' +
@@ -121,9 +122,9 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
       var iterator = iteratorFn.call(children);
       var step;
       var ii = 0;
-      while (!(step = iterator.next()).done) {
-        child = step.value;
-        nextName = nextNamePrefix + getComponentKey(child, ii++);
+      while (iterator && !(step = iterator.next()).done) {
+        child = step != null && step.value;
+        nextName = nextNamePrefix + getReactElementKey(child, ii++);
         subtreeCount += traverseAllChildren(
           child,
           nextName,
@@ -138,12 +139,12 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
           'instead.' +
           getCurrentStackAddendum();
       }
-      var childrenString = '' + children;
+      var childrenString = '' + (children: ReactElement);
       invariant(
         false,
         'Objects are not valid as a React child (found: %s).%s',
         childrenString === '[object Object]'
-          ? 'object with keys {' + Object.keys(children).join(', ') + '}'
+          ? 'object with keys {' + Object.keys((children: ReactElement)).join(', ') + '}'
           : childrenString,
         addendum,
       );
@@ -154,7 +155,7 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
 }
 
 var userProvidedKeyEscapeRegex = /\/+/g;
-function escapeUserProvidedKey(text) {
+function escapeUserProvidedKey(text: string) {
   return ('' + text).replace(userProvidedKeyEscapeRegex, '$&/');
 }
 
@@ -188,7 +189,7 @@ function mapSingleChildIntoContext(bookKeeping, child, childKey) {
         // traverseAllChildren used to do for objects as children
         keyPrefix +
           (mappedChild.key && (!child || child.key !== mappedChild.key)
-            ? escapeUserProvidedKey(mappedChild.key) + '/'
+            ? escapeUserProvidedKey((mappedChild: ReactElement).key) + '/'
             : '') +
           childKey,
       );
@@ -210,7 +211,7 @@ function mapSingleChildIntoContext(bookKeeping, child, childKey) {
  * @param {*} context Context for mapFunction.
  * @return {object} Object containing the ordered map of results.
  */
-function mapChildren(children, func, context) {
+function mapChildren(children: mixed, func: () => mixed, context?: Object): ?mixed[] {
   if (children == null) {
     return children;
   }
@@ -238,7 +239,7 @@ function mapChildren(children, func, context) {
  * @param {function(*, int)} forEachFunc
  * @param {*} forEachContext Context for forEachContext.
  */
-function forEachChildren(children, forEachFunc, forEachContext) {
+function forEachChildren(children: mixed, forEachFunc: () => mixed, forEachContext?: Object): void {
   mapChildren(children, forEachFunc, forEachContext);
 }
 
@@ -248,7 +249,7 @@ function forEachChildren(children, forEachFunc, forEachContext) {
  *
  * See https://facebook.github.io/react/docs/react-api.html#react.children.toarray
  */
-function toArray(children) {
+function toArray(children: mixed): ?mixed[] {
   if (children == null) {
     return [];
   }
@@ -264,11 +265,18 @@ function toArray(children) {
  * @param {?*} children Children tree container.
  * @return {number} The number of children.
  */
-function countChildren(children) {
+function countChildren(children: mixed): number {
   if (children == null) {
     return 0;
   }
-  return traverseAllChildren(children, '', emptyFunction.thatReturns);
+  var traverseContext = {
+    result: [],
+    keyPrefix: '',
+    func: emptyFunction.thatReturns,
+    context: {},
+    count: 0,
+  };
+  return traverseAllChildren(children, '', emptyFunction.thatReturns, traverseContext);
 }
 
 var ReactChildren = {

From a6cdc05d2897113379068d89eddc3e19bd21657d Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Mon, 8 May 2017 17:37:10 +0900
Subject: [PATCH 13/21] Type for getReactElementKey

---
 src/isomorphic/children/ReactChildren.js | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index e89d986a9ae..06adad83804 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -47,7 +47,7 @@ var didWarnAboutMaps = false;
  * @param {number} index Index that is used if a manual key is not provided.
  * @return {string}
  */
-function getReactElementKey(element: ?ReactElement, index) {
+function getReactElementKey(element, index) {
   // Do some typechecking here since we call this blindly. We want to ensure
   // that we don't block potential future ES APIs.
   if (
@@ -81,7 +81,7 @@ function traverseAllChildren(children, nameSoFar, 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 + getReactElementKey(children, 0) : nameSoFar,
+      nameSoFar === '' ? SEPARATOR + getReactElementKey((children: ReactElement), 0) : nameSoFar,
     );
     return 1;
   }
@@ -93,7 +93,7 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
 
   if (Array.isArray(children)) {
     for (var i = 0; i < children.length; i++) {
-      child = children[i];
+      child = (children[i]: ReactElement);
       nextName = nextNamePrefix + getReactElementKey(child, i);
       subtreeCount += traverseAllChildren(
         child,
@@ -123,7 +123,7 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
       var step;
       var ii = 0;
       while (iterator && !(step = iterator.next()).done) {
-        child = step != null && step.value;
+        child = step != null && (step.value: ReactElement);
         nextName = nextNamePrefix + getReactElementKey(child, ii++);
         subtreeCount += traverseAllChildren(
           child,

From 8a306690ca94a155a18237e928b45fd1775e4414 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Mon, 8 May 2017 17:48:55 +0900
Subject: [PATCH 14/21] Remove comments for types

---
 src/isomorphic/children/ReactChildren.js | 16 ----------------
 1 file changed, 16 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 06adad83804..34ac4898d21 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -42,10 +42,6 @@ var didWarnAboutMaps = false;
 
 /**
  * Generate a key string that identifies a ReactElement within a set.
- *
- * @param {*} element A ReactElement that could contain a manual key.
- * @param {number} index Index that is used if a manual key is not provided.
- * @return {string}
  */
 function getReactElementKey(element, index) {
   // Do some typechecking here since we call this blindly. We want to ensure
@@ -205,11 +201,6 @@ function mapSingleChildIntoContext(bookKeeping, child, childKey) {
  *
  * The provided mapFunction(child, key, index) will be called for each
  * leaf child.
- *
- * @param {?*} children Children tree container.
- * @param {function(*, int)} func The map function.
- * @param {*} context Context for mapFunction.
- * @return {object} Object containing the ordered map of results.
  */
 function mapChildren(children: mixed, func: () => mixed, context?: Object): ?mixed[] {
   if (children == null) {
@@ -234,10 +225,6 @@ function mapChildren(children: mixed, func: () => mixed, context?: Object): ?mix
  *
  * The provided forEachFunc(child, index) will be called for each
  * leaf child.
- *
- * @param {?*} children Children tree container.
- * @param {function(*, int)} forEachFunc
- * @param {*} forEachContext Context for forEachContext.
  */
 function forEachChildren(children: mixed, forEachFunc: () => mixed, forEachContext?: Object): void {
   mapChildren(children, forEachFunc, forEachContext);
@@ -261,9 +248,6 @@ function toArray(children: mixed): ?mixed[] {
  * `props.children`.
  *
  * See https://facebook.github.io/react/docs/react-api.html#react.children.count
- *
- * @param {?*} children Children tree container.
- * @return {number} The number of children.
  */
 function countChildren(children: mixed): number {
   if (children == null) {

From 8879aef802f0dd00b2942de2e77b295e0cd96cb7 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Mon, 8 May 2017 18:22:25 +0900
Subject: [PATCH 15/21] Run prettier

---
 src/isomorphic/children/ReactChildren.js | 43 ++++++++++++++++--------
 1 file changed, 29 insertions(+), 14 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 34ac4898d21..9228f17a8e0 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -24,9 +24,7 @@ var KeyEscapeUtils = require('KeyEscapeUtils');
 var warning = require('fbjs/lib/warning');
 
 if (__DEV__) {
-   var {
-     getCurrentStackAddendum,
-   } = require('ReactComponentTreeHook');
+  var {getCurrentStackAddendum} = require('ReactComponentTreeHook');
 }
 
 var SEPARATOR = '.';
@@ -46,9 +44,7 @@ var didWarnAboutMaps = false;
 function getReactElementKey(element, index) {
   // Do some typechecking here since we call this blindly. We want to ensure
   // that we don't block potential future ES APIs.
-  if (
-    typeof element === 'object' && element !== null && element.key != null
-  ) {
+  if (typeof element === 'object' && element !== null && element.key != null) {
     // Explicit key
     return KeyEscapeUtils.escape(element.key);
   }
@@ -70,14 +66,17 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
     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: ReactElement).$$typeof === REACT_ELEMENT_TYPE)
+    (type === 'object' &&
+      (children: ReactElement).$$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 + getReactElementKey((children: ReactElement), 0) : nameSoFar,
+      nameSoFar === ''
+        ? SEPARATOR + getReactElementKey((children: ReactElement), 0)
+        : nameSoFar,
     );
     return 1;
   }
@@ -131,7 +130,8 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
     } else if (type === 'object') {
       var addendum = '';
       if (__DEV__) {
-        addendum = ' If you meant to render a collection of children, use an array ' +
+        addendum =
+          ' If you meant to render a collection of children, use an array ' +
           'instead.' +
           getCurrentStackAddendum();
       }
@@ -140,7 +140,9 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
         false,
         'Objects are not valid as a React child (found: %s).%s',
         childrenString === '[object Object]'
-          ? 'object with keys {' + Object.keys((children: ReactElement)).join(', ') + '}'
+          ? 'object with keys {' +
+              Object.keys((children: ReactElement)).join(', ') +
+              '}'
           : childrenString,
         addendum,
       );
@@ -202,7 +204,11 @@ function mapSingleChildIntoContext(bookKeeping, child, childKey) {
  * The provided mapFunction(child, key, index) will be called for each
  * leaf child.
  */
-function mapChildren(children: mixed, func: () => mixed, context?: Object): ?mixed[] {
+function mapChildren(
+  children: mixed,
+  func: () => mixed,
+  context?: Object,
+): ?(mixed[]) {
   if (children == null) {
     return children;
   }
@@ -226,7 +232,11 @@ function mapChildren(children: mixed, func: () => mixed, context?: Object): ?mix
  * The provided forEachFunc(child, index) will be called for each
  * leaf child.
  */
-function forEachChildren(children: mixed, forEachFunc: () => mixed, forEachContext?: Object): void {
+function forEachChildren(
+  children: mixed,
+  forEachFunc: () => mixed,
+  forEachContext?: Object,
+): void {
   mapChildren(children, forEachFunc, forEachContext);
 }
 
@@ -236,7 +246,7 @@ function forEachChildren(children: mixed, forEachFunc: () => mixed, forEachConte
  *
  * See https://facebook.github.io/react/docs/react-api.html#react.children.toarray
  */
-function toArray(children: mixed): ?mixed[] {
+function toArray(children: mixed): ?(mixed[]) {
   if (children == null) {
     return [];
   }
@@ -260,7 +270,12 @@ function countChildren(children: mixed): number {
     context: {},
     count: 0,
   };
-  return traverseAllChildren(children, '', emptyFunction.thatReturns, traverseContext);
+  return traverseAllChildren(
+    children,
+    '',
+    emptyFunction.thatReturns,
+    traverseContext,
+  );
 }
 
 var ReactChildren = {

From d57fab82447f210e4f5e7b101875e84da8c739fe Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Tue, 9 May 2017 09:50:33 +0900
Subject: [PATCH 16/21] Do not allocate results with forEach

---
 src/isomorphic/children/ReactChildren.js | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 9228f17a8e0..780448d0c3f 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -224,6 +224,11 @@ function mapChildren(
   return result;
 }
 
+function forEachSingleChild(bookKeeping, child, name) {
+  var {func, context} = bookKeeping;
+  func.call(context, child, bookKeeping.count++);
+}
+
 /**
  * Iterates through children that are typically specified as `props.children`.
  *
@@ -237,7 +242,15 @@ function forEachChildren(
   forEachFunc: () => mixed,
   forEachContext?: Object,
 ): void {
-  mapChildren(children, forEachFunc, forEachContext);
+  if (children == null) {
+    return;
+  }
+  var traverseContext = {
+    func: forEachFunc,
+    context: forEachContext,
+    count: 0,
+  };
+  traverseAllChildren(children, '', forEachSingleChild, traverseContext);
 }
 
 /**

From 4ceb58fb23f32bbf1e3f850a6608c2690688f9f8 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Tue, 9 May 2017 09:51:06 +0900
Subject: [PATCH 17/21] Remove unnecessary traverseContext

---
 src/isomorphic/children/ReactChildren.js | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 780448d0c3f..eef9988c397 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -276,19 +276,7 @@ function countChildren(children: mixed): number {
   if (children == null) {
     return 0;
   }
-  var traverseContext = {
-    result: [],
-    keyPrefix: '',
-    func: emptyFunction.thatReturns,
-    context: {},
-    count: 0,
-  };
-  return traverseAllChildren(
-    children,
-    '',
-    emptyFunction.thatReturns,
-    traverseContext,
-  );
+  return traverseAllChildren(children, '', emptyFunction.thatReturnsNull, null);
 }
 
 var ReactChildren = {

From 87aefbf30a48994fb6a3b776fe42aa7e1f707c99 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Tue, 9 May 2017 09:58:32 +0900
Subject: [PATCH 18/21] Record fiber tests

---
 scripts/fiber/tests-passing.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/fiber/tests-passing.txt b/scripts/fiber/tests-passing.txt
index 2e36948c29a..06b48abf157 100644
--- a/scripts/fiber/tests-passing.txt
+++ b/scripts/fiber/tests-passing.txt
@@ -41,6 +41,7 @@ scripts/shared/__tests__/evalToString-test.js
 * should throw when it finds other types
 
 src/isomorphic/children/__tests__/ReactChildren-test.js
+* should support single child without key
 * should support identity for simple
 * should treat single arrayless child as being in array
 * should treat single child in array as expected

From d920c9b79c2789878d1ac4846a0216dfd6993e04 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Mon, 12 Jun 2017 16:16:52 +0900
Subject: [PATCH 19/21] Rebase #9903

---
 src/isomorphic/children/ReactChildren.js | 41 +++++++++++++++++-------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index eef9988c397..dda95776ee8 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -13,17 +13,19 @@
 'use strict';
 
 var ReactElement = require('ReactElement');
-
 var emptyFunction = require('fbjs/lib/emptyFunction');
-
-var REACT_ELEMENT_TYPE = require('ReactElementSymbol');
-
-var getIteratorFn = require('getIteratorFn');
 var invariant = require('fbjs/lib/invariant');
-var KeyEscapeUtils = require('KeyEscapeUtils');
-var warning = require('fbjs/lib/warning');
+
+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('ReactComponentTreeHook');
 }
 
@@ -31,10 +33,23 @@ var SEPARATOR = '.';
 var SUBSEPARATOR = ':';
 
 /**
- * This is inlined from ReactElement since this file is shared between
- * isomorphic and renderers. We could extract this to a
+ * 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 didWarnAboutMaps = false;
 
@@ -46,7 +61,7 @@ function getReactElementKey(element, index) {
   // that we don't block potential future ES APIs.
   if (typeof element === 'object' && element !== null && element.key != null) {
     // Explicit key
-    return KeyEscapeUtils.escape(element.key);
+    return escape(element.key);
   }
   // Implicit key determined by the index in the set
   return index.toString(36);
@@ -98,8 +113,10 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
       );
     }
   } else {
-    var iteratorFn = getIteratorFn(children);
-    if (iteratorFn) {
+    var iteratorFn =
+      (ITERATOR_SYMBOL && children[ITERATOR_SYMBOL]) ||
+      children[FAUX_ITERATOR_SYMBOL];
+    if (typeof iteratorFn === 'function') {
       if (__DEV__) {
         // Warn about using Maps as children
         if (children != null && iteratorFn === children.entries) {

From 96b675c6234b939d68124ed90994e68cff1d1403 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Thu, 15 Jun 2017 13:53:02 +0900
Subject: [PATCH 20/21] Fix flow errors with some $FlowFixMe

---
 src/isomorphic/children/ReactChildren.js | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index dda95776ee8..53252d60681 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -67,11 +67,17 @@ function getReactElementKey(element, index) {
   return index.toString(36);
 }
 
-function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
+function traverseAllChildren<T: any, I>(
+  children: T,
+  nameSoFar: string,
+  callback: (context: I, children: T, nameSoFar: string) => void,
+  traverseContext: I,
+) {
   var type = typeof children;
 
   if (type === 'undefined' || type === 'boolean') {
     // All of the above are perceived as null.
+    // $FlowFixMe
     children = null;
   }
 
@@ -135,9 +141,10 @@ function traverseAllChildren(children, nameSoFar, callback, traverseContext) {
       var step;
       var ii = 0;
       while (iterator && !(step = iterator.next()).done) {
-        child = step != null && (step.value: ReactElement);
+        child = step != null ? (step.value: ReactElement) : null;
         nextName = nextNamePrefix + getReactElementKey(child, ii++);
         subtreeCount += traverseAllChildren(
+          // $FlowFixMe
           child,
           nextName,
           callback,
@@ -223,7 +230,7 @@ function mapSingleChildIntoContext(bookKeeping, child, childKey) {
  */
 function mapChildren(
   children: mixed,
-  func: () => mixed,
+  func: (child: mixed, count: number) => void,
   context?: Object,
 ): ?(mixed[]) {
   if (children == null) {
@@ -256,7 +263,7 @@ function forEachSingleChild(bookKeeping, child, name) {
  */
 function forEachChildren(
   children: mixed,
-  forEachFunc: () => mixed,
+  forEachFunc: (child: mixed, count: number) => void,
   forEachContext?: Object,
 ): void {
   if (children == null) {

From 61981da8e40238d821a5b06552519f0e9719dd31 Mon Sep 17 00:00:00 2001
From: Toru Kobayashi <koba0004@gmail.com>
Date: Thu, 29 Jun 2017 14:22:42 +0900
Subject: [PATCH 21/21] Fix $FlowFixMe

---
 src/isomorphic/children/ReactChildren.js | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/isomorphic/children/ReactChildren.js b/src/isomorphic/children/ReactChildren.js
index 53252d60681..5d37ed8d437 100644
--- a/src/isomorphic/children/ReactChildren.js
+++ b/src/isomorphic/children/ReactChildren.js
@@ -68,16 +68,15 @@ function getReactElementKey(element, index) {
 }
 
 function traverseAllChildren<T: any, I>(
-  children: T,
+  children: T | null,
   nameSoFar: string,
-  callback: (context: I, children: T, nameSoFar: string) => void,
+  callback: (context: I, children: T | null, nameSoFar: string) => void,
   traverseContext: I,
 ) {
   var type = typeof children;
 
   if (type === 'undefined' || type === 'boolean') {
     // All of the above are perceived as null.
-    // $FlowFixMe
     children = null;
   }
 
@@ -144,7 +143,6 @@ function traverseAllChildren<T: any, I>(
         child = step != null ? (step.value: ReactElement) : null;
         nextName = nextNamePrefix + getReactElementKey(child, ii++);
         subtreeCount += traverseAllChildren(
-          // $FlowFixMe
           child,
           nextName,
           callback,