From d7c13885e87c65ac82e3160fa14c10eb61c639d6 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Tue, 14 Nov 2023 09:38:05 -0800
Subject: [PATCH 01/33] Modularize flutter.js source.

---
 lib/web_ui/flutter_js/sources.gni             |   8 +-
 .../flutter_js/src/entrypoint_loader.js       | 135 +++++++
 lib/web_ui/flutter_js/src/flutter.js          | 382 +-----------------
 lib/web_ui/flutter_js/src/loader.js           |  45 +++
 .../flutter_js/src/service_worker_loader.js   | 150 +++++++
 lib/web_ui/flutter_js/src/trusted_types.js    |  35 ++
 6 files changed, 378 insertions(+), 377 deletions(-)
 create mode 100644 lib/web_ui/flutter_js/src/entrypoint_loader.js
 create mode 100644 lib/web_ui/flutter_js/src/loader.js
 create mode 100644 lib/web_ui/flutter_js/src/service_worker_loader.js
 create mode 100644 lib/web_ui/flutter_js/src/trusted_types.js

diff --git a/lib/web_ui/flutter_js/sources.gni b/lib/web_ui/flutter_js/sources.gni
index ee00c55efeb7b..02dab6e3e5e16 100644
--- a/lib/web_ui/flutter_js/sources.gni
+++ b/lib/web_ui/flutter_js/sources.gni
@@ -2,4 +2,10 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-flutter_js_source_list = [ "src/flutter.js" ]
+flutter_js_source_list = [
+  "src/entrypoint_loader.js",
+  "src/flutter.js",
+  "src/loader.js",
+  "src/service_worker_loader.js",
+  "src/trusted_types.js",
+]
diff --git a/lib/web_ui/flutter_js/src/entrypoint_loader.js b/lib/web_ui/flutter_js/src/entrypoint_loader.js
new file mode 100644
index 0000000000000..b5a29918b4a31
--- /dev/null
+++ b/lib/web_ui/flutter_js/src/entrypoint_loader.js
@@ -0,0 +1,135 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+const baseUri = ensureTrailingSlash(getBaseURI());
+
+function getBaseURI() {
+  const base = document.querySelector("base");
+  return (base && base.getAttribute("href")) || "";
+}
+
+function ensureTrailingSlash(uri) {
+  if (uri == "") {
+    return uri;
+  }
+  return uri.endsWith("/") ? uri : `${uri}/`;
+}
+
+/**
+ * Handles injecting the main Flutter web entrypoint (main.dart.js), and notifying
+ * the user when Flutter is ready, through `didCreateEngineInitializer`.
+ *
+ * @see https://docs.flutter.dev/development/platform-integration/web/initialization
+ */
+export class FlutterEntrypointLoader {
+  /**
+   * Creates a FlutterEntrypointLoader.
+   */
+  constructor() {
+    // Watchdog to prevent injecting the main entrypoint multiple times.
+    this._scriptLoaded = false;
+  }
+  /**
+   * Injects a TrustedTypesPolicy (or undefined if the feature is not supported).
+   * @param {TrustedTypesPolicy | undefined} policy
+   */
+  setTrustedTypesPolicy(policy) {
+    this._ttPolicy = policy;
+  }
+  /**
+   * Loads flutter main entrypoint, specified by `entrypointUrl`, and calls a
+   * user-specified `onEntrypointLoaded` callback with an EngineInitializer
+   * object when it's done.
+   *
+   * @param {*} options
+   * @returns {Promise | undefined} that will eventually resolve with an
+   * EngineInitializer, or will be rejected with the error caused by the loader.
+   * Returns undefined when an `onEntrypointLoaded` callback is supplied in `options`.
+   */
+  async loadEntrypoint(options) {
+    const { entrypointUrl = `${baseUri}main.dart.js`, onEntrypointLoaded, nonce } =
+      options || {};
+    return this._loadEntrypoint(entrypointUrl, onEntrypointLoaded, nonce);
+  }
+  /**
+   * Resolves the promise created by loadEntrypoint, and calls the `onEntrypointLoaded`
+   * function supplied by the user (if needed).
+   *
+   * Called by Flutter through `_flutter.loader.didCreateEngineInitializer` method,
+   * which is bound to the correct instance of the FlutterEntrypointLoader by
+   * the FlutterLoader object.
+   *
+   * @param {Function} engineInitializer @see https://github.com/flutter/engine/blob/main/lib/web_ui/lib/src/engine/js_interop/js_loader.dart#L42
+   */
+  didCreateEngineInitializer(engineInitializer) {
+    if (typeof this._didCreateEngineInitializerResolve === "function") {
+      this._didCreateEngineInitializerResolve(engineInitializer);
+      // Remove the resolver after the first time, so Flutter Web can hot restart.
+      this._didCreateEngineInitializerResolve = null;
+      // Make the engine revert to "auto" initialization on hot restart.
+      delete _flutter.loader.didCreateEngineInitializer;
+    }
+    if (typeof this._onEntrypointLoaded === "function") {
+      this._onEntrypointLoaded(engineInitializer);
+    }
+  }
+  /**
+   * Injects a script tag into the DOM, and configures this loader to be able to
+   * handle the "entrypoint loaded" notifications received from Flutter web.
+   *
+   * @param {string} entrypointUrl the URL of the script that will initialize
+   *                 Flutter.
+   * @param {Function} onEntrypointLoaded a callback that will be called when
+   *                   Flutter web notifies this object that the entrypoint is
+   *                   loaded.
+   * @returns {Promise | undefined} a Promise that resolves when the entrypoint
+   *                                is loaded, or undefined if `onEntrypointLoaded`
+   *                                is a function.
+   */
+  _loadEntrypoint(entrypointUrl, onEntrypointLoaded, nonce) {
+    const useCallback = typeof onEntrypointLoaded === "function";
+    if (!this._scriptLoaded) {
+      this._scriptLoaded = true;
+      const scriptTag = this._createScriptTag(entrypointUrl, nonce);
+      if (useCallback) {
+        // Just inject the script tag, and return nothing; Flutter will call
+        // `didCreateEngineInitializer` when it's done.
+        console.debug("Injecting <script> tag. Using callback.");
+        this._onEntrypointLoaded = onEntrypointLoaded;
+        document.body.append(scriptTag);
+      } else {
+        // Inject the script tag and return a promise that will get resolved
+        // with the EngineInitializer object from Flutter when it calls
+        // `didCreateEngineInitializer` later.
+        return new Promise((resolve, reject) => {
+          console.debug(
+            "Injecting <script> tag. Using Promises. Use the callback approach instead!"
+          );
+          this._didCreateEngineInitializerResolve = resolve;
+          scriptTag.addEventListener("error", reject);
+          document.body.append(scriptTag);
+        });
+      }
+    }
+  }
+  /**
+   * Creates a script tag for the given URL.
+   * @param {string} url
+   * @returns {HTMLScriptElement}
+   */
+  _createScriptTag(url, nonce) {
+    const scriptTag = document.createElement("script");
+    scriptTag.type = "application/javascript";
+    if (nonce) {
+      scriptTag.nonce = nonce;
+    }
+    // Apply TrustedTypes validation, if available.
+    let trustedUrl = url;
+    if (this._ttPolicy != null) {
+      trustedUrl = this._ttPolicy.createScriptURL(url);
+    }
+    scriptTag.src = trustedUrl;
+    return scriptTag;
+  }
+}
diff --git a/lib/web_ui/flutter_js/src/flutter.js b/lib/web_ui/flutter_js/src/flutter.js
index fcdc9c32742f5..57208c7287129 100644
--- a/lib/web_ui/flutter_js/src/flutter.js
+++ b/lib/web_ui/flutter_js/src/flutter.js
@@ -2,380 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-var _flutter = window._flutter;
-if (!_flutter) {
-  _flutter = window._flutter = {};
-}
-_flutter.loader = null;
-
-(function () {
-  "use strict";
-
-  const baseUri = ensureTrailingSlash(getBaseURI());
-
-  function getBaseURI() {
-    const base = document.querySelector("base");
-    return (base && base.getAttribute("href")) || "";
-  }
-
-  function ensureTrailingSlash(uri) {
-    if (uri == "") {
-      return uri;
-    }
-    return uri.endsWith("/") ? uri : `${uri}/`;
-  }
-
-  /**
-   * Wraps `promise` in a timeout of the given `duration` in ms.
-   *
-   * Resolves/rejects with whatever the original `promises` does, or rejects
-   * if `promise` takes longer to complete than `duration`. In that case,
-   * `debugName` is used to compose a legible error message.
-   *
-   * If `duration` is < 0, the original `promise` is returned unchanged.
-   * @param {Promise} promise
-   * @param {number} duration
-   * @param {string} debugName
-   * @returns {Promise} a wrapped promise.
-   */
-  async function timeout(promise, duration, debugName) {
-    if (duration < 0) {
-      return promise;
-    }
-    let timeoutId;
-    const _clock = new Promise((_, reject) => {
-      timeoutId = setTimeout(() => {
-        reject(
-          new Error(
-            `${debugName} took more than ${duration}ms to resolve. Moving on.`,
-            {
-              cause: timeout,
-            }
-          )
-        );
-      }, duration);
-    });
-
-    return Promise.race([promise, _clock]).finally(() => {
-      clearTimeout(timeoutId);
-    });
-  }
-
-  /**
-   * Handles the creation of a TrustedTypes `policy` that validates URLs based
-   * on an (optional) incoming array of RegExes.
-   */
-  class FlutterTrustedTypesPolicy {
-    /**
-     * Constructs the policy.
-     * @param {[RegExp]} validPatterns the patterns to test URLs
-     * @param {String} policyName the policy name (optional)
-     */
-    constructor(validPatterns, policyName = "flutter-js") {
-      const patterns = validPatterns || [
-        /\.js$/,
-      ];
-      if (window.trustedTypes) {
-        this.policy = trustedTypes.createPolicy(policyName, {
-          createScriptURL: function(url) {
-            const parsed = new URL(url, window.location);
-            const file = parsed.pathname.split("/").pop();
-            const matches = patterns.some((pattern) => pattern.test(file));
-            if (matches) {
-              return parsed.toString();
-            }
-            console.error(
-              "URL rejected by TrustedTypes policy",
-              policyName, ":", url, "(download prevented)");
-          }
-        });
-      }
-    }
-  }
-
-  /**
-   * Handles loading/reloading Flutter's service worker, if configured.
-   *
-   * @see: https://developers.google.com/web/fundamentals/primers/service-workers
-   */
-  class FlutterServiceWorkerLoader {
-    /**
-     * Injects a TrustedTypesPolicy (or undefined if the feature is not supported).
-     * @param {TrustedTypesPolicy | undefined} policy
-     */
-    setTrustedTypesPolicy(policy) {
-      this._ttPolicy = policy;
-    }
-
-    /**
-     * Returns a Promise that resolves when the latest Flutter service worker,
-     * configured by `settings` has been loaded and activated.
-     *
-     * Otherwise, the promise is rejected with an error message.
-     * @param {*} settings Service worker settings
-     * @returns {Promise} that resolves when the latest serviceWorker is ready.
-     */
-    loadServiceWorker(settings) {
-      if (settings == null) {
-        // In the future, settings = null -> uninstall service worker?
-        console.debug("Null serviceWorker configuration. Skipping.");
-        return Promise.resolve();
-      }
-      if (!("serviceWorker" in navigator)) {
-        let errorMessage = "Service Worker API unavailable.";
-        if (!window.isSecureContext) {
-          errorMessage += "\nThe current context is NOT secure."
-          errorMessage += "\nRead more: https://developer.mozilla.org/en-US/docs/Web/Security/Secure_Contexts";
-        }
-        return Promise.reject(
-          new Error(errorMessage)
-        );
-      }
-      const {
-        serviceWorkerVersion,
-        serviceWorkerUrl = `${baseUri}flutter_service_worker.js?v=${serviceWorkerVersion}`,
-        timeoutMillis = 4000,
-      } = settings;
-
-      // Apply the TrustedTypes policy, if present.
-      let url = serviceWorkerUrl;
-      if (this._ttPolicy != null) {
-        url = this._ttPolicy.createScriptURL(url);
-      }
-
-      const serviceWorkerActivation = navigator.serviceWorker
-        .register(url)
-        .then((serviceWorkerRegistration) => this._getNewServiceWorker(serviceWorkerRegistration, serviceWorkerVersion))
-        .then(this._waitForServiceWorkerActivation);
-
-      // Timeout race promise
-      return timeout(
-        serviceWorkerActivation,
-        timeoutMillis,
-        "prepareServiceWorker"
-      );
-    }
-
-    /**
-     * Returns the latest service worker for the given `serviceWorkerRegistration`.
-     *
-     * This might return the current service worker, if there's no new service worker
-     * awaiting to be installed/updated.
-     *
-     * @param {ServiceWorkerRegistration} serviceWorkerRegistration
-     * @param {String} serviceWorkerVersion
-     * @returns {Promise<ServiceWorker>}
-     */
-    async _getNewServiceWorker(serviceWorkerRegistration, serviceWorkerVersion) {
-      if (!serviceWorkerRegistration.active && (serviceWorkerRegistration.installing || serviceWorkerRegistration.waiting)) {
-        // No active web worker and we have installed or are installing
-        // one for the first time. Simply wait for it to activate.
-        console.debug("Installing/Activating first service worker.");
-        return serviceWorkerRegistration.installing || serviceWorkerRegistration.waiting;
-      } else if (!serviceWorkerRegistration.active.scriptURL.endsWith(serviceWorkerVersion)) {
-        // When the app updates the serviceWorkerVersion changes, so we
-        // need to ask the service worker to update.
-        const newRegistration = await serviceWorkerRegistration.update();
-        console.debug("Updating service worker.");
-        return newRegistration.installing || newRegistration.waiting || newRegistration.active;
-      } else {
-        console.debug("Loading from existing service worker.");
-        return serviceWorkerRegistration.active;
-      }
-    }
+import { FlutterLoader } from './loader.js';
 
-    /**
-     * Returns a Promise that resolves when the `serviceWorker` changes its
-     * state to "activated".
-     *
-     * @param {ServiceWorker} serviceWorker
-     * @returns {Promise<void>}
-     */
-    async _waitForServiceWorkerActivation(serviceWorker) {
-      if (!serviceWorker || serviceWorker.state == "activated") {
-        if (!serviceWorker) {
-          throw new Error("Cannot activate a null service worker!");
-        } else {
-          console.debug("Service worker already active.");
-          return;
-        }
-      }
-      return new Promise((resolve, _) => {
-        serviceWorker.addEventListener("statechange", () => {
-          if (serviceWorker.state == "activated") {
-            console.debug("Activated new service worker.");
-            resolve();
-          }
-        });
-      });
-    }
-  }
-
-  /**
-   * Handles injecting the main Flutter web entrypoint (main.dart.js), and notifying
-   * the user when Flutter is ready, through `didCreateEngineInitializer`.
-   *
-   * @see https://docs.flutter.dev/development/platform-integration/web/initialization
-   */
-  class FlutterEntrypointLoader {
-    /**
-     * Creates a FlutterEntrypointLoader.
-     */
-    constructor() {
-      // Watchdog to prevent injecting the main entrypoint multiple times.
-      this._scriptLoaded = false;
-    }
-
-    /**
-     * Injects a TrustedTypesPolicy (or undefined if the feature is not supported).
-     * @param {TrustedTypesPolicy | undefined} policy
-     */
-    setTrustedTypesPolicy(policy) {
-      this._ttPolicy = policy;
-    }
-
-    /**
-     * Loads flutter main entrypoint, specified by `entrypointUrl`, and calls a
-     * user-specified `onEntrypointLoaded` callback with an EngineInitializer
-     * object when it's done.
-     *
-     * @param {*} options
-     * @returns {Promise | undefined} that will eventually resolve with an
-     * EngineInitializer, or will be rejected with the error caused by the loader.
-     * Returns undefined when an `onEntrypointLoaded` callback is supplied in `options`.
-     */
-    async loadEntrypoint(options) {
-      const { entrypointUrl = `${baseUri}main.dart.js`, onEntrypointLoaded, nonce } =
-        options || {};
-
-      return this._loadEntrypoint(entrypointUrl, onEntrypointLoaded, nonce);
-    }
-
-    /**
-     * Resolves the promise created by loadEntrypoint, and calls the `onEntrypointLoaded`
-     * function supplied by the user (if needed).
-     *
-     * Called by Flutter through `_flutter.loader.didCreateEngineInitializer` method,
-     * which is bound to the correct instance of the FlutterEntrypointLoader by
-     * the FlutterLoader object.
-     *
-     * @param {Function} engineInitializer @see https://github.com/flutter/engine/blob/main/lib/web_ui/lib/src/engine/js_interop/js_loader.dart#L42
-     */
-    didCreateEngineInitializer(engineInitializer) {
-      if (typeof this._didCreateEngineInitializerResolve === "function") {
-        this._didCreateEngineInitializerResolve(engineInitializer);
-        // Remove the resolver after the first time, so Flutter Web can hot restart.
-        this._didCreateEngineInitializerResolve = null;
-        // Make the engine revert to "auto" initialization on hot restart.
-        delete _flutter.loader.didCreateEngineInitializer;
-      }
-      if (typeof this._onEntrypointLoaded === "function") {
-        this._onEntrypointLoaded(engineInitializer);
-      }
-    }
-
-    /**
-     * Injects a script tag into the DOM, and configures this loader to be able to
-     * handle the "entrypoint loaded" notifications received from Flutter web.
-     *
-     * @param {string} entrypointUrl the URL of the script that will initialize
-     *                 Flutter.
-     * @param {Function} onEntrypointLoaded a callback that will be called when
-     *                   Flutter web notifies this object that the entrypoint is
-     *                   loaded.
-     * @returns {Promise | undefined} a Promise that resolves when the entrypoint
-     *                                is loaded, or undefined if `onEntrypointLoaded`
-     *                                is a function.
-     */
-    _loadEntrypoint(entrypointUrl, onEntrypointLoaded, nonce) {
-      const useCallback = typeof onEntrypointLoaded === "function";
-
-      if (!this._scriptLoaded) {
-        this._scriptLoaded = true;
-        const scriptTag = this._createScriptTag(entrypointUrl, nonce);
-        if (useCallback) {
-          // Just inject the script tag, and return nothing; Flutter will call
-          // `didCreateEngineInitializer` when it's done.
-          console.debug("Injecting <script> tag. Using callback.");
-          this._onEntrypointLoaded = onEntrypointLoaded;
-          document.body.append(scriptTag);
-        } else {
-          // Inject the script tag and return a promise that will get resolved
-          // with the EngineInitializer object from Flutter when it calls
-          // `didCreateEngineInitializer` later.
-          return new Promise((resolve, reject) => {
-            console.debug(
-              "Injecting <script> tag. Using Promises. Use the callback approach instead!"
-            );
-            this._didCreateEngineInitializerResolve = resolve;
-            scriptTag.addEventListener("error", reject);
-            document.body.append(scriptTag);
-          });
-        }
-      }
-    }
-
-    /**
-     * Creates a script tag for the given URL.
-     * @param {string} url
-     * @returns {HTMLScriptElement}
-     */
-    _createScriptTag(url, nonce) {
-      const scriptTag = document.createElement("script");
-      scriptTag.type = "application/javascript";
-      if (nonce) {
-        scriptTag.nonce = nonce;
-      }
-      // Apply TrustedTypes validation, if available.
-      let trustedUrl = url;
-      if (this._ttPolicy != null) {
-        trustedUrl = this._ttPolicy.createScriptURL(url);
-      }
-      scriptTag.src = trustedUrl;
-      return scriptTag;
-    }
-  }
-
-  /**
-   * The public interface of _flutter.loader. Exposes two methods:
-   * * loadEntrypoint (which coordinates the default Flutter web loading procedure)
-   * * didCreateEngineInitializer (which is called by Flutter to notify that its
-   *                              Engine is ready to be initialized)
-   */
-  class FlutterLoader {
-    /**
-     * Initializes the Flutter web app.
-     * @param {*} options
-     * @returns {Promise?} a (Deprecated) Promise that will eventually resolve
-     *                     with an EngineInitializer, or will be rejected with
-     *                     any error caused by the loader. Or Null, if the user
-     *                     supplies an `onEntrypointLoaded` Function as an option.
-     */
-    async loadEntrypoint(options) {
-      const { serviceWorker, ...entrypoint } = options || {};
-
-      // A Trusted Types policy that is going to be used by the loader.
-      const flutterTT = new FlutterTrustedTypesPolicy();
-
-      // The FlutterServiceWorkerLoader instance could be injected as a dependency
-      // (and dynamically imported from a module if not present).
-      const serviceWorkerLoader = new FlutterServiceWorkerLoader();
-      serviceWorkerLoader.setTrustedTypesPolicy(flutterTT.policy);
-      await serviceWorkerLoader.loadServiceWorker(serviceWorker).catch(e => {
-        // Regardless of what happens with the injection of the SW, the show must go on
-        console.warn("Exception while loading service worker:", e);
-      });
-
-      // The FlutterEntrypointLoader instance could be injected as a dependency
-      // (and dynamically imported from a module if not present).
-      const entrypointLoader = new FlutterEntrypointLoader();
-      entrypointLoader.setTrustedTypesPolicy(flutterTT.policy);
-      // Install the `didCreateEngineInitializer` listener where Flutter web expects it to be.
-      this.didCreateEngineInitializer =
-        entrypointLoader.didCreateEngineInitializer.bind(entrypointLoader);
-      return entrypointLoader.loadEntrypoint(entrypoint);
-    }
-  }
-
-  _flutter.loader = new FlutterLoader();
-})();
+if (!window._flutter) {
+  window._flutter = {
+    loader: new FlutterLoader()
+  };
+}
diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
new file mode 100644
index 0000000000000..9e73a3f7e1b8f
--- /dev/null
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -0,0 +1,45 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import { FlutterEntrypointLoader } from './entrypoint_loader.js';
+import { FlutterServiceWorkerLoader } from './service_worker_loader.js';
+import { FlutterTrustedTypesPolicy } from './trusted_types.js';
+
+/**
+ * The public interface of _flutter.loader. Exposes two methods:
+ * * loadEntrypoint (which coordinates the default Flutter web loading procedure)
+ * * didCreateEngineInitializer (which is called by Flutter to notify that its
+ *                              Engine is ready to be initialized)
+ */
+export class FlutterLoader {
+  /**
+   * Initializes the Flutter web app.
+   * @param {*} options
+   * @returns {Promise?} a (Deprecated) Promise that will eventually resolve
+   *                     with an EngineInitializer, or will be rejected with
+   *                     any error caused by the loader. Or Null, if the user
+   *                     supplies an `onEntrypointLoaded` Function as an option.
+   */
+  async loadEntrypoint(options) {
+    const { serviceWorker, ...entrypoint } = options || {};
+    // A Trusted Types policy that is going to be used by the loader.
+    const flutterTT = new FlutterTrustedTypesPolicy();
+    // The FlutterServiceWorkerLoader instance could be injected as a dependency
+    // (and dynamically imported from a module if not present).
+    const serviceWorkerLoader = new FlutterServiceWorkerLoader();
+    serviceWorkerLoader.setTrustedTypesPolicy(flutterTT.policy);
+    await serviceWorkerLoader.loadServiceWorker(serviceWorker).catch(e => {
+      // Regardless of what happens with the injection of the SW, the show must go on
+      console.warn("Exception while loading service worker:", e);
+    });
+    // The FlutterEntrypointLoader instance could be injected as a dependency
+    // (and dynamically imported from a module if not present).
+    const entrypointLoader = new FlutterEntrypointLoader();
+    entrypointLoader.setTrustedTypesPolicy(flutterTT.policy);
+    // Install the `didCreateEngineInitializer` listener where Flutter web expects it to be.
+    this.didCreateEngineInitializer =
+      entrypointLoader.didCreateEngineInitializer.bind(entrypointLoader);
+    return entrypointLoader.loadEntrypoint(entrypoint);
+  }
+}
diff --git a/lib/web_ui/flutter_js/src/service_worker_loader.js b/lib/web_ui/flutter_js/src/service_worker_loader.js
new file mode 100644
index 0000000000000..d96e92a83a36d
--- /dev/null
+++ b/lib/web_ui/flutter_js/src/service_worker_loader.js
@@ -0,0 +1,150 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * Wraps `promise` in a timeout of the given `duration` in ms.
+ *
+ * Resolves/rejects with whatever the original `promises` does, or rejects
+ * if `promise` takes longer to complete than `duration`. In that case,
+ * `debugName` is used to compose a legible error message.
+ *
+ * If `duration` is < 0, the original `promise` is returned unchanged.
+ * @param {Promise} promise
+ * @param {number} duration
+ * @param {string} debugName
+ * @returns {Promise} a wrapped promise.
+ */
+async function timeout(promise, duration, debugName) {
+  if (duration < 0) {
+    return promise;
+  }
+  let timeoutId;
+  const _clock = new Promise((_, reject) => {
+    timeoutId = setTimeout(() => {
+      reject(
+        new Error(
+          `${debugName} took more than ${duration}ms to resolve. Moving on.`,
+          {
+            cause: timeout,
+          }
+        )
+      );
+    }, duration);
+  });
+  return Promise.race([promise, _clock]).finally(() => {
+    clearTimeout(timeoutId);
+  });
+}
+
+/**
+ * Handles loading/reloading Flutter's service worker, if configured.
+ *
+ * @see: https://developers.google.com/web/fundamentals/primers/service-workers
+ */
+export class FlutterServiceWorkerLoader {
+  /**
+   * Injects a TrustedTypesPolicy (or undefined if the feature is not supported).
+   * @param {TrustedTypesPolicy | undefined} policy
+   */
+  setTrustedTypesPolicy(policy) {
+    this._ttPolicy = policy;
+  }
+  /**
+   * Returns a Promise that resolves when the latest Flutter service worker,
+   * configured by `settings` has been loaded and activated.
+   *
+   * Otherwise, the promise is rejected with an error message.
+   * @param {*} settings Service worker settings
+   * @returns {Promise} that resolves when the latest serviceWorker is ready.
+   */
+  loadServiceWorker(settings) {
+    if (settings == null) {
+      // In the future, settings = null -> uninstall service worker?
+      console.debug("Null serviceWorker configuration. Skipping.");
+      return Promise.resolve();
+    }
+    if (!("serviceWorker" in navigator)) {
+      let errorMessage = "Service Worker API unavailable.";
+      if (!window.isSecureContext) {
+        errorMessage += "\nThe current context is NOT secure."
+        errorMessage += "\nRead more: https://developer.mozilla.org/en-US/docs/Web/Security/Secure_Contexts";
+      }
+      return Promise.reject(
+        new Error(errorMessage)
+      );
+    }
+    const {
+      serviceWorkerVersion,
+      serviceWorkerUrl = `${baseUri}flutter_service_worker.js?v=${serviceWorkerVersion}`,
+      timeoutMillis = 4000,
+    } = settings;
+    // Apply the TrustedTypes policy, if present.
+    let url = serviceWorkerUrl;
+    if (this._ttPolicy != null) {
+      url = this._ttPolicy.createScriptURL(url);
+    }
+    const serviceWorkerActivation = navigator.serviceWorker
+      .register(url)
+      .then((serviceWorkerRegistration) => this._getNewServiceWorker(serviceWorkerRegistration, serviceWorkerVersion))
+      .then(this._waitForServiceWorkerActivation);
+    // Timeout race promise
+    return timeout(
+      serviceWorkerActivation,
+      timeoutMillis,
+      "prepareServiceWorker"
+    );
+  }
+  /**
+   * Returns the latest service worker for the given `serviceWorkerRegistration`.
+   *
+   * This might return the current service worker, if there's no new service worker
+   * awaiting to be installed/updated.
+   *
+   * @param {ServiceWorkerRegistration} serviceWorkerRegistration
+   * @param {String} serviceWorkerVersion
+   * @returns {Promise<ServiceWorker>}
+   */
+  async _getNewServiceWorker(serviceWorkerRegistration, serviceWorkerVersion) {
+    if (!serviceWorkerRegistration.active && (serviceWorkerRegistration.installing || serviceWorkerRegistration.waiting)) {
+      // No active web worker and we have installed or are installing
+      // one for the first time. Simply wait for it to activate.
+      console.debug("Installing/Activating first service worker.");
+      return serviceWorkerRegistration.installing || serviceWorkerRegistration.waiting;
+    } else if (!serviceWorkerRegistration.active.scriptURL.endsWith(serviceWorkerVersion)) {
+      // When the app updates the serviceWorkerVersion changes, so we
+      // need to ask the service worker to update.
+      const newRegistration = await serviceWorkerRegistration.update();
+      console.debug("Updating service worker.");
+      return newRegistration.installing || newRegistration.waiting || newRegistration.active;
+    } else {
+      console.debug("Loading from existing service worker.");
+      return serviceWorkerRegistration.active;
+    }
+  }
+  /**
+   * Returns a Promise that resolves when the `serviceWorker` changes its
+   * state to "activated".
+   *
+   * @param {ServiceWorker} serviceWorker
+   * @returns {Promise<void>}
+   */
+  async _waitForServiceWorkerActivation(serviceWorker) {
+    if (!serviceWorker || serviceWorker.state == "activated") {
+      if (!serviceWorker) {
+        throw new Error("Cannot activate a null service worker!");
+      } else {
+        console.debug("Service worker already active.");
+        return;
+      }
+    }
+    return new Promise((resolve, _) => {
+      serviceWorker.addEventListener("statechange", () => {
+        if (serviceWorker.state == "activated") {
+          console.debug("Activated new service worker.");
+          resolve();
+        }
+      });
+    });
+  }
+}
diff --git a/lib/web_ui/flutter_js/src/trusted_types.js b/lib/web_ui/flutter_js/src/trusted_types.js
new file mode 100644
index 0000000000000..6ae4ffde976b8
--- /dev/null
+++ b/lib/web_ui/flutter_js/src/trusted_types.js
@@ -0,0 +1,35 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * Handles the creation of a TrustedTypes `policy` that validates URLs based
+ * on an (optional) incoming array of RegExes.
+ */
+export class FlutterTrustedTypesPolicy {
+  /**
+   * Constructs the policy.
+   * @param {[RegExp]} validPatterns the patterns to test URLs
+   * @param {String} policyName the policy name (optional)
+   */
+  constructor(validPatterns, policyName = "flutter-js") {
+    const patterns = validPatterns || [
+      /\.js$/,
+    ];
+    if (window.trustedTypes) {
+      this.policy = trustedTypes.createPolicy(policyName, {
+        createScriptURL: function(url) {
+          const parsed = new URL(url, window.location);
+          const file = parsed.pathname.split("/").pop();
+          const matches = patterns.some((pattern) => pattern.test(file));
+          if (matches) {
+            return parsed.toString();
+          }
+          console.error(
+            "URL rejected by TrustedTypes policy",
+            policyName, ":", url, "(download prevented)");
+        }
+      });
+    }
+  }
+}

From b25b444ef3fb77a0780cdc1cb22091545d89ce87 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Tue, 21 Nov 2023 12:02:23 -0800
Subject: [PATCH 02/33] Started new load function.

---
 .../flutter_js/src/browser_environment.js     | 51 +++++++++++++++++++
 lib/web_ui/flutter_js/src/loader.js           | 25 +++++++++
 lib/web_ui/flutter_js/src/types.d.ts          | 30 +++++++++++
 3 files changed, 106 insertions(+)
 create mode 100644 lib/web_ui/flutter_js/src/browser_environment.js
 create mode 100644 lib/web_ui/flutter_js/src/types.d.ts

diff --git a/lib/web_ui/flutter_js/src/browser_environment.js b/lib/web_ui/flutter_js/src/browser_environment.js
new file mode 100644
index 0000000000000..936296c13cfed
--- /dev/null
+++ b/lib/web_ui/flutter_js/src/browser_environment.js
@@ -0,0 +1,51 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * @returns {import("./types").BrowserEnvironment}
+ */
+export const detectBrowserEnvironment = () => {
+    return {
+        hasImageCodecs: hasImageCodecs(),
+        hasChromiumBreakIterators: hasChromiumBreakIterators(),
+        supportsWasmGC: supportsWasmGC(),
+        crossOriginIsolated: window.crossOriginIsolated,
+    };
+}
+
+const isBlink = () => {
+    return (Navigator.vendor === 'Google Inc.') ||
+        (Navigator.agent == 'Edg/');
+}
+
+const hasImageCodecs = () => {
+    if (typeof ImageDecoder !== 'undefined') {
+        return false;
+    }
+    // TODO(yjbanov): https://github.com/flutter/flutter/issues/122761
+    // Frequently, when a browser launches an API that other browsers already
+    // support, there are subtle incompatibilities that may cause apps to crash if,
+    // we blindly adopt the new implementation. This check prevents us from picking
+    // up potentially incompatible implementations of ImagdeDecoder API. Instead,
+    // when a new browser engine launches the API, we'll evaluate it and enable it
+    // explicitly.
+    if (!isBlink()) {
+        return false;
+    }
+    return true;
+}
+
+const hasChromiumBreakIterators = () => {
+    return (typeof Intl.v8BreakIterator !== "undefined") &&
+        (typeof Intl.Segmenter !== "undefined");
+}
+
+const supportsWasmGC = () => {
+    // This attempts to instantiate a wasm module that only will validate if the
+    // final WasmGC spec is implemented in the browser.
+    //
+    // Copied from https://github.com/GoogleChromeLabs/wasm-feature-detect/blob/main/src/detectors/gc/index.js
+    const bytes = [0, 97, 115, 109, 1, 0, 0, 0, 1, 5, 1, 95, 1, 120, 0];
+    return WebAssembly.validate(new Uint8Array(bytes));
+}
diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
index 9e73a3f7e1b8f..6e92d4fbbdb7f 100644
--- a/lib/web_ui/flutter_js/src/loader.js
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import { detectBrowserEnvironment } from './browser_environment.js';
 import { FlutterEntrypointLoader } from './entrypoint_loader.js';
 import { FlutterServiceWorkerLoader } from './service_worker_loader.js';
 import { FlutterTrustedTypesPolicy } from './trusted_types.js';
@@ -42,4 +43,28 @@ export class FlutterLoader {
       entrypointLoader.didCreateEngineInitializer.bind(entrypointLoader);
     return entrypointLoader.loadEntrypoint(entrypoint);
   }
+
+  async load({
+    serviceWorkerSettings,
+    onEntrypointLoaded,
+    options,
+  } = {}) {
+    options ??= {};
+    const browserEnvironment = detectBrowserEnvironment();
+    const buildConfig = _flutter.buildConfig;
+    if (!buildConfig) {
+        throw "FlutterLoader.load requires _flutter.buildConfig to be set";
+    }
+    const buildIsCompatible = (build) => {
+
+    };
+    const build = buildConfig.builds.find(buildIsCompatible);
+    if (!build) {
+        throw "FlutterLoader could not find a build compatible with configuration and environment.";
+    }
+    const deps = _loadBuildDependencies(build);
+  }
+
+  _loadBuildDependencies(build) {
+  }
 }
diff --git a/lib/web_ui/flutter_js/src/types.d.ts b/lib/web_ui/flutter_js/src/types.d.ts
new file mode 100644
index 0000000000000..790b525c859cf
--- /dev/null
+++ b/lib/web_ui/flutter_js/src/types.d.ts
@@ -0,0 +1,30 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+export type CompileTarget =
+    "dart2js" |
+    "dartdevc" |
+    "dart2wasm";
+
+export type WebRenderer =
+    "html" |
+    "canvaskit" |
+    "skwasm";
+
+export interface ApplicationBuild {
+    target: CompileTarget;
+    supportedRenderers: WebRenderer[];
+}
+
+export interface BuildConfig {
+    serviceWorkerVersion: string;
+    builds: ApplicationBuild[];
+}
+
+export interface BrowserEnvironment {
+    hasImageCodecs: boolean;
+    hasChromiumBreakIterators: boolean; 
+    supportsWasmGC: boolean;
+    crossOriginIsolated: boolean;
+}

From 766079df1a072f8259d9baa7592d40c8ba59b8fa Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 7 Dec 2023 16:34:20 -0800
Subject: [PATCH 03/33] More flutter js loader stuff.

---
 lib/web_ui/flutter_js/src/canvaskit_loader.js | 32 ++++++++++++++++
 lib/web_ui/flutter_js/src/loader.js           | 37 ++++++++++++++++---
 lib/web_ui/flutter_js/src/skwasm_loader.js    | 33 +++++++++++++++++
 lib/web_ui/flutter_js/src/types.d.ts          |  2 +-
 4 files changed, 97 insertions(+), 7 deletions(-)
 create mode 100644 lib/web_ui/flutter_js/src/canvaskit_loader.js
 create mode 100644 lib/web_ui/flutter_js/src/skwasm_loader.js

diff --git a/lib/web_ui/flutter_js/src/canvaskit_loader.js b/lib/web_ui/flutter_js/src/canvaskit_loader.js
new file mode 100644
index 0000000000000..5958a958a547a
--- /dev/null
+++ b/lib/web_ui/flutter_js/src/canvaskit_loader.js
@@ -0,0 +1,32 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+export const loadCanvasKit = (deps, options, browserEnvironment) => {
+  window.flutterCanvasKitLoaded = new Promise((resolve) => {
+    const supportsChromiumCanvasKit = browserEnvironment.hasChromiumBreakIterators && browserEnvironment.hasImageCodecs;
+    if (!supportsChromiumCanvasKit && options.canvasKitVariant == "chromium") {
+      throw "Chromium CanvasKit variant specifically requested, but unsupported in this browser";
+    }
+    const useChromiumCanvasKit = supportsChromiumCanvasKit && (options.canvasKitVariant !== "full");
+    const baseUrl = options.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineVersion}`;
+    const canvasKitUrl = useChromiumCanvasKit ? `${baseUrl}/canvaskit.js` : `${baseUrl}/chromium/canvaskit.js`;
+    const trustedCanvasKitUrl = deps.flutterTT.policy.createScriptURL(canvasKitUrl);
+    const script = document.createElement("script");
+    script.src = trustedCanvasKitUrl;
+    script.addEventListener('load', async () => {
+      try {
+        const canvasKit = await CanvasKitInit();
+        window.flutterCanvasKit = canvasKit;
+        resolve(canvasKit);  
+      } catch (e) {
+        reject(e);
+      }
+    });
+    script.addEventListener('error', (e) => {
+      reject(e);
+    });
+    document.body.appendChild(script);
+  });
+  return window.flutterCanvasKitLoaded;
+}
diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
index 6e92d4fbbdb7f..d502fbaa72b0e 100644
--- a/lib/web_ui/flutter_js/src/loader.js
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -53,18 +53,43 @@ export class FlutterLoader {
     const browserEnvironment = detectBrowserEnvironment();
     const buildConfig = _flutter.buildConfig;
     if (!buildConfig) {
-        throw "FlutterLoader.load requires _flutter.buildConfig to be set";
+      throw "FlutterLoader.load requires _flutter.buildConfig to be set";
+    }
+
+    const rendererIsCompatible = (renderer) => {
+      switch (renderer) {
+        case "skwasm":
+          return browserEnvironment.crossOriginIsolated 
+            && browserEnvironment.hasChromiumBreakIterators 
+            && browserEnvironment.hasImageCodecs 
+            && browserEnvironment.supportsWasmGC;
+        default:
+          return true;
+      }
     }
-    const buildIsCompatible = (build) => {
 
+    const buildIsCompatible = (build) => {
+      if (build.compileTarget == "dart2wasm" && !browserEnvironment.supportsWasmGC) {
+        return false;
+      }
+      if (options.renderer && options.renderer != build.renderer) {
+        return false;
+      }
+      return rendererIsCompatible(build.renderer);
     };
     const build = buildConfig.builds.find(buildIsCompatible);
     if (!build) {
-        throw "FlutterLoader could not find a build compatible with configuration and environment.";
+      throw "FlutterLoader could not find a build compatible with configuration and environment.";
     }
-    const deps = _loadBuildDependencies(build);
-  }
 
-  _loadBuildDependencies(build) {
+    const deps = {};
+    deps.flutterTT = new FlutterTrustedTypesPolicy();
+    deps.serviceWorkerLoader = new FlutterServiceWorkerLoader();
+    deps.serviceWorkerLoader.setTrustedTypesPolicy(deps.flutterTT);
+    if (build.renderer == "canvaskit") {
+      deps.canvasKit = loadCanvasKit();
+    } else if (build.renderer == "skwasm") {
+      deps.skwasm = loadSkwasm();
+    }
   }
 }
diff --git a/lib/web_ui/flutter_js/src/skwasm_loader.js b/lib/web_ui/flutter_js/src/skwasm_loader.js
new file mode 100644
index 0000000000000..afa771509782d
--- /dev/null
+++ b/lib/web_ui/flutter_js/src/skwasm_loader.js
@@ -0,0 +1,33 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+export const loadSkwasm = (deps, options, browserEnvironment) => {
+    return new Promise((resolve) => {
+      const supportsChromiumCanvasKit = browserEnvironment.hasChromiumBreakIterators && browserEnvironment.hasImageCodecs;
+      if (!supportsChromiumCanvasKit && options.canvasKitVariant == "chromium") {
+        throw "Chromium CanvasKit variant specifically requested, but unsupported in this browser";
+      }
+      const useChromiumCanvasKit = supportsChromiumCanvasKit && (options.canvasKitVariant !== "full");
+      const baseUrl = options.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineVersion}`;
+      const canvasKitUrl = useChromiumCanvasKit ? `${baseUrl}/skwasm.js` : `${baseUrl}/chromium/skwasm.js`;
+      const trustedCanvasKitUrl = deps.flutterTT.policy.createScriptURL(canvasKitUrl);
+      const script = document.createElement("script");
+      script.src = trustedCanvasKitUrl;
+      script.addEventListener('load', async () => {
+        try {
+          const canvasKit = await CanvasKitInit();
+          window.flutterCanvasKit = canvasKit;
+          resolve(canvasKit);  
+        } catch (e) {
+          reject(e);
+        }
+      });
+      script.addEventListener('error', (e) => {
+        reject(e);
+      });
+      document.body.appendChild(script);
+    });
+    return window.flutterCanvasKitLoaded;
+  }
+  
\ No newline at end of file
diff --git a/lib/web_ui/flutter_js/src/types.d.ts b/lib/web_ui/flutter_js/src/types.d.ts
index 790b525c859cf..6a94d49de63a5 100644
--- a/lib/web_ui/flutter_js/src/types.d.ts
+++ b/lib/web_ui/flutter_js/src/types.d.ts
@@ -14,7 +14,7 @@ export type WebRenderer =
 
 export interface ApplicationBuild {
     target: CompileTarget;
-    supportedRenderers: WebRenderer[];
+    renderer: WebRenderer;
 }
 
 export interface BuildConfig {

From 4157dd5eb4e7a267ede3f8a579abd74dfdd5a484 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Fri, 8 Dec 2023 16:32:11 -0800
Subject: [PATCH 04/33] Some tests running (but hard coded currently).

---
 lib/web_ui/dev/test_dart2js.js                | 11 +++++++++-
 lib/web_ui/flutter_js/sources.gni             |  3 +++
 .../flutter_js/src/browser_environment.js     |  8 +++++---
 lib/web_ui/flutter_js/src/canvaskit_loader.js |  2 +-
 lib/web_ui/flutter_js/src/loader.js           | 20 ++++++++++++++++++-
 lib/web_ui/flutter_js/src/types.d.ts          |  1 +
 6 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/lib/web_ui/dev/test_dart2js.js b/lib/web_ui/dev/test_dart2js.js
index 22f55b522bb03..6f24a42a18cba 100644
--- a/lib/web_ui/dev/test_dart2js.js
+++ b/lib/web_ui/dev/test_dart2js.js
@@ -51,8 +51,17 @@ export const runTest = (configuration) => {
     return;
   }
 
+  _flutter.buildConfig = {
+    builds: [{
+      compileTarget: "dart2js",
+      renderer: "canvaskit",
+      url: link.href + '.browser_test.dart.js',
+    }]
+  };
+
   try {
-    window._flutter.loader.loadEntrypoint({
+    window._flutter.loader.load({
+      options: configuration,
       entrypointUrl: link.href + '.browser_test.dart.js',
       onEntrypointLoaded: function(engineInitializer) {
         engineInitializer.initializeEngine(configuration).then(function(appRunner) {
diff --git a/lib/web_ui/flutter_js/sources.gni b/lib/web_ui/flutter_js/sources.gni
index 02dab6e3e5e16..1bd0b3b96b966 100644
--- a/lib/web_ui/flutter_js/sources.gni
+++ b/lib/web_ui/flutter_js/sources.gni
@@ -3,9 +3,12 @@
 # found in the LICENSE file.
 
 flutter_js_source_list = [
+  "src/browser_environment.js",
+  "src/canvaskit_loader.js",
   "src/entrypoint_loader.js",
   "src/flutter.js",
   "src/loader.js",
   "src/service_worker_loader.js",
+  "src/skwasm_loader.js",
   "src/trusted_types.js",
 ]
diff --git a/lib/web_ui/flutter_js/src/browser_environment.js b/lib/web_ui/flutter_js/src/browser_environment.js
index 936296c13cfed..8c891d0945457 100644
--- a/lib/web_ui/flutter_js/src/browser_environment.js
+++ b/lib/web_ui/flutter_js/src/browser_environment.js
@@ -15,12 +15,13 @@ export const detectBrowserEnvironment = () => {
 }
 
 const isBlink = () => {
-    return (Navigator.vendor === 'Google Inc.') ||
-        (Navigator.agent == 'Edg/');
+    return (navigator.vendor === 'Google Inc.') ||
+        (navigator.agent == 'Edg/');
 }
 
 const hasImageCodecs = () => {
-    if (typeof ImageDecoder !== 'undefined') {
+    if (typeof ImageDecoder === 'undefined') {
+        console.log("no image decoder");
         return false;
     }
     // TODO(yjbanov): https://github.com/flutter/flutter/issues/122761
@@ -31,6 +32,7 @@ const hasImageCodecs = () => {
     // when a new browser engine launches the API, we'll evaluate it and enable it
     // explicitly.
     if (!isBlink()) {
+        console.log("not blink");
         return false;
     }
     return true;
diff --git a/lib/web_ui/flutter_js/src/canvaskit_loader.js b/lib/web_ui/flutter_js/src/canvaskit_loader.js
index 5958a958a547a..d6c0030edb1b0 100644
--- a/lib/web_ui/flutter_js/src/canvaskit_loader.js
+++ b/lib/web_ui/flutter_js/src/canvaskit_loader.js
@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 export const loadCanvasKit = (deps, options, browserEnvironment) => {
-  window.flutterCanvasKitLoaded = new Promise((resolve) => {
+  window.flutterCanvasKitLoaded = new Promise((resolve, reject) => {
     const supportsChromiumCanvasKit = browserEnvironment.hasChromiumBreakIterators && browserEnvironment.hasImageCodecs;
     if (!supportsChromiumCanvasKit && options.canvasKitVariant == "chromium") {
       throw "Chromium CanvasKit variant specifically requested, but unsupported in this browser";
diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
index d502fbaa72b0e..6ae16219b3d3d 100644
--- a/lib/web_ui/flutter_js/src/loader.js
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -6,6 +6,8 @@ import { detectBrowserEnvironment } from './browser_environment.js';
 import { FlutterEntrypointLoader } from './entrypoint_loader.js';
 import { FlutterServiceWorkerLoader } from './service_worker_loader.js';
 import { FlutterTrustedTypesPolicy } from './trusted_types.js';
+import { loadCanvasKit } from './canvaskit_loader.js';
+import { loadSkwasm } from './skwasm_loader.js';
 
 /**
  * The public interface of _flutter.loader. Exposes two methods:
@@ -86,10 +88,26 @@ export class FlutterLoader {
     deps.flutterTT = new FlutterTrustedTypesPolicy();
     deps.serviceWorkerLoader = new FlutterServiceWorkerLoader();
     deps.serviceWorkerLoader.setTrustedTypesPolicy(deps.flutterTT);
+    await deps.serviceWorkerLoader.loadServiceWorker(serviceWorkerSettings).catch(e => {
+      // Regardless of what happens with the injection of the SW, the show must go on
+      console.warn("Exception while loading service worker:", e);
+    });
     if (build.renderer == "canvaskit") {
-      deps.canvasKit = loadCanvasKit();
+      deps.canvasKit = loadCanvasKit(deps, options, browserEnvironment);
     } else if (build.renderer == "skwasm") {
       deps.skwasm = loadSkwasm();
     }
+
+    // The FlutterEntrypointLoader instance could be injected as a dependency
+    // (and dynamically imported from a module if not present).
+    const entrypointLoader = new FlutterEntrypointLoader();
+    entrypointLoader.setTrustedTypesPolicy(deps.flutterTT.policy);
+    // Install the `didCreateEngineInitializer` listener where Flutter web expects it to be.
+    this.didCreateEngineInitializer =
+      entrypointLoader.didCreateEngineInitializer.bind(entrypointLoader);
+    return entrypointLoader.loadEntrypoint({
+      onEntrypointLoaded,
+      entrypointUrl: build.url ?? "/main.dart.js",
+    });
   }
 }
diff --git a/lib/web_ui/flutter_js/src/types.d.ts b/lib/web_ui/flutter_js/src/types.d.ts
index 6a94d49de63a5..3df038c23d108 100644
--- a/lib/web_ui/flutter_js/src/types.d.ts
+++ b/lib/web_ui/flutter_js/src/types.d.ts
@@ -20,6 +20,7 @@ export interface ApplicationBuild {
 export interface BuildConfig {
     serviceWorkerVersion: string;
     builds: ApplicationBuild[];
+    url: string?;
 }
 
 export interface BrowserEnvironment {

From 43f3c6f3f5a0e8bf722b3396911747ebef512433 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Tue, 12 Dec 2023 17:34:38 -0800
Subject: [PATCH 05/33] dart2wasm and dart2js both working (although no skwasm
 yet).

---
 lib/web_ui/dev/test_platform.dart             | 59 +++++++++++--------
 lib/web_ui/flutter_js/src/canvaskit_loader.js |  2 +-
 .../flutter_js/src/entrypoint_loader.js       | 50 ++++++++++++++--
 lib/web_ui/flutter_js/src/loader.js           |  5 +-
 lib/web_ui/flutter_js/src/trusted_types.js    |  1 +
 lib/web_ui/flutter_js/src/types.d.ts          | 25 +++++---
 .../src/engine/canvaskit/canvaskit_api.dart   |  3 +
 .../lib/src/engine/canvaskit/renderer.dart    |  6 ++
 8 files changed, 112 insertions(+), 39 deletions(-)

diff --git a/lib/web_ui/dev/test_platform.dart b/lib/web_ui/dev/test_platform.dart
index 90d3172560ca6..6c1f040a375f1 100644
--- a/lib/web_ui/dev/test_platform.dart
+++ b/lib/web_ui/dev/test_platform.dart
@@ -526,47 +526,60 @@ class BrowserPlatform extends PlatformPlugin {
     }
   }
 
+  String _makeBuildConfigString(String scriptBase, CompileConfiguration config) {
+    return config.compiler == Compiler.dart2wasm ? '''
+      {
+        compileTarget: "${config.compiler.name}",
+        renderer: "${config.renderer.name}",
+        mainWasmPath: "$scriptBase.browser_test.dart.wasm",
+        jsSupportRuntimePath: "$scriptBase.browser_test.dart.mjs",
+      }
+''' : '''
+      {
+        compileTarget: "${config.compiler.name}",
+        renderer: "${config.renderer.name}",
+        mainJsPath: "$scriptBase.browser_test.dart.js",
+      }
+''';
+  }
+
   /// Serves the HTML file that bootstraps the test.
   shelf.Response _testBootstrapHandler(shelf.Request request) {
     final String path = p.fromUri(request.url);
 
     if (path.endsWith('.html')) {
       final String test = '${p.withoutExtension(path)}.dart';
-
-      final bool linkSkwasm = suite.testBundle.compileConfig.renderer == Renderer.skwasm;
-      // Link to the Dart wrapper.
       final String scriptBase = htmlEscape.convert(p.basename(test));
-      final String link = '<link rel="x-dart-test" href="$scriptBase"${linkSkwasm ? " skwasm" : ""}>';
 
-      final String bootstrapScript = isWasm ? '''
+      final String bootstrapScript = '''
+<script src="/flutter_js/flutter.js"></script>
 <script>
-  window.flutterConfiguration = {
-    canvasKitBaseUrl: "/canvaskit/",
-    // Some of our tests rely on color emoji
-    useColorEmoji: true,
-    canvasKitVariant: "${getCanvasKitVariant()}",
+  _flutter.buildConfig = {
+    builds: [
+      ${_makeBuildConfigString(scriptBase, suite.testBundle.compileConfig)}
+    ]
   };
-</script>
-<script src="/test_dart2wasm.js"></script>
-      ''' : '''
-<script src="/flutter_js/flutter.js"></script>
-<script type="module">
-  import { runTest } from "/test_dart2js.js";
-
-  runTest({
-    canvasKitBaseUrl: "/canvaskit/",
-    // Some of our tests rely on color emoji
-    useColorEmoji: true,
-    canvasKitVariant: "${getCanvasKitVariant()}",
+  _flutter.loader.load({
+    options: {
+      canvasKitBaseUrl: "/canvaskit/",
+      // Some of our tests rely on color emoji
+      useColorEmoji: true,
+      canvasKitVariant: "${getCanvasKitVariant()}",
+    },
+    onEntrypointLoaded: function(engineInitializer) {
+      engineInitializer.initializeEngine(configuration).then(function(appRunner) {
+        appRunner.runApp();
+      });
+    },
   });
 </script>
 ''';
+
       return shelf.Response.ok('''
         <!DOCTYPE html>
         <html>
         <head>
           <meta name="assetBase" content="/">
-          $link
           $bootstrapScript
         </head>
         </html>
diff --git a/lib/web_ui/flutter_js/src/canvaskit_loader.js b/lib/web_ui/flutter_js/src/canvaskit_loader.js
index d6c0030edb1b0..749872087456d 100644
--- a/lib/web_ui/flutter_js/src/canvaskit_loader.js
+++ b/lib/web_ui/flutter_js/src/canvaskit_loader.js
@@ -26,7 +26,7 @@ export const loadCanvasKit = (deps, options, browserEnvironment) => {
     script.addEventListener('error', (e) => {
       reject(e);
     });
-    document.body.appendChild(script);
+    document.head.appendChild(script);
   });
   return window.flutterCanvasKitLoaded;
 }
diff --git a/lib/web_ui/flutter_js/src/entrypoint_loader.js b/lib/web_ui/flutter_js/src/entrypoint_loader.js
index b5a29918b4a31..ec53bc1838a2d 100644
--- a/lib/web_ui/flutter_js/src/entrypoint_loader.js
+++ b/lib/web_ui/flutter_js/src/entrypoint_loader.js
@@ -50,8 +50,25 @@ export class FlutterEntrypointLoader {
   async loadEntrypoint(options) {
     const { entrypointUrl = `${baseUri}main.dart.js`, onEntrypointLoaded, nonce } =
       options || {};
-    return this._loadEntrypoint(entrypointUrl, onEntrypointLoaded, nonce);
+    return this._loadJSEntrypoint(entrypointUrl, onEntrypointLoaded, nonce);
   }
+
+  async load(build, options) {
+    let { onEntrypointLoaded, nonce } = options;
+    onEntrypointLoaded ??= (engineInitializer) => {
+      engineInitializer.initializeEngine(options).then((appRunner) => appRunner.runApp())
+    };
+    console.log(`TARGET: ${build.compileTarget}`);
+    if (build.compileTarget == "dart2wasm") {
+      return this._loadWasmEntrypoint(build, onEntrypointLoaded);
+    } else {
+      const mainPath = build.mainJsPath ?? "main.dart.js";
+      const entrypointUrl = `${baseUri}${mainPath}`;
+      console.log(`ENTRYPOINT URL: ${entrypointUrl}`);
+      return this._loadJSEntrypoint(entrypointUrl, onEntrypointLoaded, nonce);
+    }
+  }
+
   /**
    * Resolves the promise created by loadEntrypoint, and calls the `onEntrypointLoaded`
    * function supplied by the user (if needed).
@@ -87,7 +104,7 @@ export class FlutterEntrypointLoader {
    *                                is loaded, or undefined if `onEntrypointLoaded`
    *                                is a function.
    */
-  _loadEntrypoint(entrypointUrl, onEntrypointLoaded, nonce) {
+  _loadJSEntrypoint(entrypointUrl, onEntrypointLoaded, nonce) {
     const useCallback = typeof onEntrypointLoaded === "function";
     if (!this._scriptLoaded) {
       this._scriptLoaded = true;
@@ -97,7 +114,7 @@ export class FlutterEntrypointLoader {
         // `didCreateEngineInitializer` when it's done.
         console.debug("Injecting <script> tag. Using callback.");
         this._onEntrypointLoaded = onEntrypointLoaded;
-        document.body.append(scriptTag);
+        document.head.append(scriptTag);
       } else {
         // Inject the script tag and return a promise that will get resolved
         // with the EngineInitializer object from Flutter when it calls
@@ -108,11 +125,36 @@ export class FlutterEntrypointLoader {
           );
           this._didCreateEngineInitializerResolve = resolve;
           scriptTag.addEventListener("error", reject);
-          document.body.append(scriptTag);
+          document.head.append(scriptTag);
         });
       }
     }
   }
+
+  async _loadWasmEntrypoint(build, onEntrypointLoaded) {
+    console.log("load wasm entrypoint");
+    if (!this._scriptLoaded) {
+      console.log("script not yet loaded");
+      this._scriptLoaded = true;
+
+      this._onEntrypointLoaded = onEntrypointLoaded;
+      const { mainWasmPath, jsSupportRuntimePath } = build;
+      const moduleUri = `${baseUri}${mainWasmPath}`;
+      let jsSupportRuntimeUri = `${baseUri}${jsSupportRuntimePath}`;
+      if (this._ttPolicy != null) {
+        jsSupportRuntimeUri = this._ttPolicy.createScriptURL(jsSupportRuntimeUri);
+      }  
+      const dartModulePromise = WebAssembly.compileStreaming(fetch(moduleUri));
+
+      console.log("about to load support runtime");
+      const jsSupportRuntime = await import(jsSupportRuntimeUri);
+      console.log("about to instantiate module");
+      const moduleInstance = await jsSupportRuntime.instantiate(dartModulePromise, {});
+      console.log("invoking module!");
+      await jsSupportRuntime.invoke(moduleInstance);
+    }
+  }
+
   /**
    * Creates a script tag for the given URL.
    * @param {string} url
diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
index 6ae16219b3d3d..d36e27c47e3fa 100644
--- a/lib/web_ui/flutter_js/src/loader.js
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -105,9 +105,6 @@ export class FlutterLoader {
     // Install the `didCreateEngineInitializer` listener where Flutter web expects it to be.
     this.didCreateEngineInitializer =
       entrypointLoader.didCreateEngineInitializer.bind(entrypointLoader);
-    return entrypointLoader.loadEntrypoint({
-      onEntrypointLoaded,
-      entrypointUrl: build.url ?? "/main.dart.js",
-    });
+    return entrypointLoader.load(build, onEntrypointLoaded);
   }
 }
diff --git a/lib/web_ui/flutter_js/src/trusted_types.js b/lib/web_ui/flutter_js/src/trusted_types.js
index 6ae4ffde976b8..527f06f7b59bc 100644
--- a/lib/web_ui/flutter_js/src/trusted_types.js
+++ b/lib/web_ui/flutter_js/src/trusted_types.js
@@ -15,6 +15,7 @@ export class FlutterTrustedTypesPolicy {
   constructor(validPatterns, policyName = "flutter-js") {
     const patterns = validPatterns || [
       /\.js$/,
+      /\.mjs$/,
     ];
     if (window.trustedTypes) {
       this.policy = trustedTypes.createPolicy(policyName, {
diff --git a/lib/web_ui/flutter_js/src/types.d.ts b/lib/web_ui/flutter_js/src/types.d.ts
index 3df038c23d108..e5b628a717aae 100644
--- a/lib/web_ui/flutter_js/src/types.d.ts
+++ b/lib/web_ui/flutter_js/src/types.d.ts
@@ -2,25 +2,36 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-export type CompileTarget =
-    "dart2js" |
-    "dartdevc" |
-    "dart2wasm";
+type JSCompileTarget = "dart2js" | "dartdevc";
+type WasmCompileTarget = "dart2wasm";
+
+export type CompileTarget = JSCompileTarget | WasmCompileTarget;
 
 export type WebRenderer =
     "html" |
     "canvaskit" |
     "skwasm";
 
-export interface ApplicationBuild {
-    target: CompileTarget;
+interface ApplicationBuildBase {
     renderer: WebRenderer;
 }
 
+export interface JSApplicationBuild extends ApplicationBuildBase {
+    compileTarget: JSCompileTarget;
+    mainJsPath: String;
+}
+
+export interface WasmApplicationBuild extends ApplicationBuildBase {
+    compileTarget: WasmCompileTarget;
+    mainWasmPath: String;
+    jsSupportRuntimePath: String;
+}
+
+export type ApplicationBuild = JSApplicationBuild | WasmApplicationBuild;
+
 export interface BuildConfig {
     serviceWorkerVersion: string;
     builds: ApplicationBuild[];
-    url: string?;
 }
 
 export interface BrowserEnvironment {
diff --git a/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart b/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart
index fea055f16bbec..a73379473ea34 100644
--- a/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart
+++ b/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart
@@ -43,6 +43,9 @@ external set windowFlutterCanvasKit(CanvasKit? value);
 @JS('window.flutterCanvasKit')
 external CanvasKit? get windowFlutterCanvasKit;
 
+@JS('window.flutterCanvasKitLoaded')
+external JSPromise? get windowFlutterCanvasKitLoaded;
+
 @JS()
 @anonymous
 @staticInterop
diff --git a/lib/web_ui/lib/src/engine/canvaskit/renderer.dart b/lib/web_ui/lib/src/engine/canvaskit/renderer.dart
index 567fac6849883..15a658b9646ea 100644
--- a/lib/web_ui/lib/src/engine/canvaskit/renderer.dart
+++ b/lib/web_ui/lib/src/engine/canvaskit/renderer.dart
@@ -64,8 +64,14 @@ class CanvasKitRenderer implements Renderer {
   Future<void> initialize() async {
     _initialized ??= () async {
       if (windowFlutterCanvasKit != null) {
+        print('ALREADY LOADED');
         canvasKit = windowFlutterCanvasKit!;
+      } else if (windowFlutterCanvasKitLoaded != null) {
+        print('PRELOAD');
+        // CanvasKit is being preloaded by flutter.js. Wait for it to complete.
+        canvasKit = await promiseToFuture<CanvasKit>(windowFlutterCanvasKitLoaded!);
       } else {
+        print('LOAD OURSELVES');
         canvasKit = await downloadCanvasKit();
         windowFlutterCanvasKit = canvasKit;
       }

From 94d8dfa1d148af9afb89e6a6fc404b905d8a6457 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Wed, 13 Dec 2023 15:49:04 -0800
Subject: [PATCH 06/33] Many tests are working.

---
 lib/web_ui/dev/test_platform.dart             |  9 +----
 .../flutter_js/src/browser_environment.js     |  2 -
 lib/web_ui/flutter_js/src/canvaskit_loader.js |  8 ++--
 .../flutter_js/src/entrypoint_loader.js       | 37 ++++++++++++-------
 lib/web_ui/flutter_js/src/loader.js           | 12 +++---
 lib/web_ui/flutter_js/src/skwasm_loader.js    | 25 +++++--------
 .../lib/src/engine/canvaskit/renderer.dart    |  3 --
 .../test/canvaskit/hot_restart_test.dart      |  2 -
 .../initialization/services_vs_ui_test.dart   |  1 -
 9 files changed, 44 insertions(+), 55 deletions(-)

diff --git a/lib/web_ui/dev/test_platform.dart b/lib/web_ui/dev/test_platform.dart
index 6c1f040a375f1..1b437b7374efb 100644
--- a/lib/web_ui/dev/test_platform.dart
+++ b/lib/web_ui/dev/test_platform.dart
@@ -156,7 +156,7 @@ class BrowserPlatform extends PlatformPlugin {
   Uri get url => server.url.resolve('/');
 
   bool get isWasm => suite.testBundle.compileConfig.compiler == Compiler.dart2wasm;
-  bool get needsCrossOriginIsolated => isWasm && suite.testBundle.compileConfig.renderer == Renderer.skwasm;
+  bool get needsCrossOriginIsolated => true; //isWasm && suite.testBundle.compileConfig.renderer == Renderer.skwasm;
 
   /// A [OneOffHandler] for servicing WebSocket connections for
   /// [BrowserManager]s.
@@ -560,17 +560,12 @@ class BrowserPlatform extends PlatformPlugin {
     ]
   };
   _flutter.loader.load({
-    options: {
+    config: {
       canvasKitBaseUrl: "/canvaskit/",
       // Some of our tests rely on color emoji
       useColorEmoji: true,
       canvasKitVariant: "${getCanvasKitVariant()}",
     },
-    onEntrypointLoaded: function(engineInitializer) {
-      engineInitializer.initializeEngine(configuration).then(function(appRunner) {
-        appRunner.runApp();
-      });
-    },
   });
 </script>
 ''';
diff --git a/lib/web_ui/flutter_js/src/browser_environment.js b/lib/web_ui/flutter_js/src/browser_environment.js
index 8c891d0945457..185c8e05731f2 100644
--- a/lib/web_ui/flutter_js/src/browser_environment.js
+++ b/lib/web_ui/flutter_js/src/browser_environment.js
@@ -21,7 +21,6 @@ const isBlink = () => {
 
 const hasImageCodecs = () => {
     if (typeof ImageDecoder === 'undefined') {
-        console.log("no image decoder");
         return false;
     }
     // TODO(yjbanov): https://github.com/flutter/flutter/issues/122761
@@ -32,7 +31,6 @@ const hasImageCodecs = () => {
     // when a new browser engine launches the API, we'll evaluate it and enable it
     // explicitly.
     if (!isBlink()) {
-        console.log("not blink");
         return false;
     }
     return true;
diff --git a/lib/web_ui/flutter_js/src/canvaskit_loader.js b/lib/web_ui/flutter_js/src/canvaskit_loader.js
index 749872087456d..c1d8ce2ce093b 100644
--- a/lib/web_ui/flutter_js/src/canvaskit_loader.js
+++ b/lib/web_ui/flutter_js/src/canvaskit_loader.js
@@ -2,14 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-export const loadCanvasKit = (deps, options, browserEnvironment) => {
+export const loadCanvasKit = (deps, config, browserEnvironment) => {
   window.flutterCanvasKitLoaded = new Promise((resolve, reject) => {
     const supportsChromiumCanvasKit = browserEnvironment.hasChromiumBreakIterators && browserEnvironment.hasImageCodecs;
-    if (!supportsChromiumCanvasKit && options.canvasKitVariant == "chromium") {
+    if (!supportsChromiumCanvasKit && config.canvasKitVariant == "chromium") {
       throw "Chromium CanvasKit variant specifically requested, but unsupported in this browser";
     }
-    const useChromiumCanvasKit = supportsChromiumCanvasKit && (options.canvasKitVariant !== "full");
-    const baseUrl = options.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineVersion}`;
+    const useChromiumCanvasKit = supportsChromiumCanvasKit && (config.canvasKitVariant !== "full");
+    const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineVersion}`;
     const canvasKitUrl = useChromiumCanvasKit ? `${baseUrl}/canvaskit.js` : `${baseUrl}/chromium/canvaskit.js`;
     const trustedCanvasKitUrl = deps.flutterTT.policy.createScriptURL(canvasKitUrl);
     const script = document.createElement("script");
diff --git a/lib/web_ui/flutter_js/src/entrypoint_loader.js b/lib/web_ui/flutter_js/src/entrypoint_loader.js
index ec53bc1838a2d..e8ab0dc7c17a7 100644
--- a/lib/web_ui/flutter_js/src/entrypoint_loader.js
+++ b/lib/web_ui/flutter_js/src/entrypoint_loader.js
@@ -53,19 +53,16 @@ export class FlutterEntrypointLoader {
     return this._loadJSEntrypoint(entrypointUrl, onEntrypointLoaded, nonce);
   }
 
-  async load(build, options) {
-    let { onEntrypointLoaded, nonce } = options;
+  async load(build, deps, config, onEntrypointLoaded) {
     onEntrypointLoaded ??= (engineInitializer) => {
-      engineInitializer.initializeEngine(options).then((appRunner) => appRunner.runApp())
+      engineInitializer.initializeEngine(config).then((appRunner) => appRunner.runApp())
     };
-    console.log(`TARGET: ${build.compileTarget}`);
     if (build.compileTarget == "dart2wasm") {
-      return this._loadWasmEntrypoint(build, onEntrypointLoaded);
+      return this._loadWasmEntrypoint(build, deps, onEntrypointLoaded);
     } else {
       const mainPath = build.mainJsPath ?? "main.dart.js";
       const entrypointUrl = `${baseUri}${mainPath}`;
-      console.log(`ENTRYPOINT URL: ${entrypointUrl}`);
-      return this._loadJSEntrypoint(entrypointUrl, onEntrypointLoaded, nonce);
+      return this._loadJSEntrypoint(entrypointUrl, onEntrypointLoaded);
     }
   }
 
@@ -131,10 +128,8 @@ export class FlutterEntrypointLoader {
     }
   }
 
-  async _loadWasmEntrypoint(build, onEntrypointLoaded) {
-    console.log("load wasm entrypoint");
+  async _loadWasmEntrypoint(build, deps, onEntrypointLoaded) {
     if (!this._scriptLoaded) {
-      console.log("script not yet loaded");
       this._scriptLoaded = true;
 
       this._onEntrypointLoaded = onEntrypointLoaded;
@@ -146,11 +141,25 @@ export class FlutterEntrypointLoader {
       }  
       const dartModulePromise = WebAssembly.compileStreaming(fetch(moduleUri));
 
-      console.log("about to load support runtime");
       const jsSupportRuntime = await import(jsSupportRuntimeUri);
-      console.log("about to instantiate module");
-      const moduleInstance = await jsSupportRuntime.instantiate(dartModulePromise, {});
-      console.log("invoking module!");
+
+      let imports;
+      if (build.renderer == "skwasm") {
+        imports = (async () => {
+          const skwasmInstance = await deps.skwasm;
+          window._flutter_skwasmInstance = skwasmInstance;
+          return {
+            skwasm: skwasmInstance.wasmExports,
+            skwasmWrapper: skwasmInstance,
+            ffi: {
+              memory: skwasmInstance.wasmMemory,
+            },
+          };
+        })();
+      } else {
+        imports = {};
+      }
+      const moduleInstance = await jsSupportRuntime.instantiate(dartModulePromise, imports);
       await jsSupportRuntime.invoke(moduleInstance);
     }
   }
diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
index d36e27c47e3fa..eb54e023e304c 100644
--- a/lib/web_ui/flutter_js/src/loader.js
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -49,9 +49,9 @@ export class FlutterLoader {
   async load({
     serviceWorkerSettings,
     onEntrypointLoaded,
-    options,
+    config,
   } = {}) {
-    options ??= {};
+    config ??= {};
     const browserEnvironment = detectBrowserEnvironment();
     const buildConfig = _flutter.buildConfig;
     if (!buildConfig) {
@@ -74,7 +74,7 @@ export class FlutterLoader {
       if (build.compileTarget == "dart2wasm" && !browserEnvironment.supportsWasmGC) {
         return false;
       }
-      if (options.renderer && options.renderer != build.renderer) {
+      if (config.renderer && config.renderer != build.renderer) {
         return false;
       }
       return rendererIsCompatible(build.renderer);
@@ -93,9 +93,9 @@ export class FlutterLoader {
       console.warn("Exception while loading service worker:", e);
     });
     if (build.renderer == "canvaskit") {
-      deps.canvasKit = loadCanvasKit(deps, options, browserEnvironment);
+      deps.canvasKit = loadCanvasKit(deps, config, browserEnvironment);
     } else if (build.renderer == "skwasm") {
-      deps.skwasm = loadSkwasm();
+      deps.skwasm = loadSkwasm(deps, config, browserEnvironment);
     }
 
     // The FlutterEntrypointLoader instance could be injected as a dependency
@@ -105,6 +105,6 @@ export class FlutterLoader {
     // Install the `didCreateEngineInitializer` listener where Flutter web expects it to be.
     this.didCreateEngineInitializer =
       entrypointLoader.didCreateEngineInitializer.bind(entrypointLoader);
-    return entrypointLoader.load(build, onEntrypointLoaded);
+    return entrypointLoader.load(build, deps, config, onEntrypointLoaded);
   }
 }
diff --git a/lib/web_ui/flutter_js/src/skwasm_loader.js b/lib/web_ui/flutter_js/src/skwasm_loader.js
index afa771509782d..b826d06ab44e1 100644
--- a/lib/web_ui/flutter_js/src/skwasm_loader.js
+++ b/lib/web_ui/flutter_js/src/skwasm_loader.js
@@ -2,23 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-export const loadSkwasm = (deps, options, browserEnvironment) => {
-    return new Promise((resolve) => {
-      const supportsChromiumCanvasKit = browserEnvironment.hasChromiumBreakIterators && browserEnvironment.hasImageCodecs;
-      if (!supportsChromiumCanvasKit && options.canvasKitVariant == "chromium") {
-        throw "Chromium CanvasKit variant specifically requested, but unsupported in this browser";
-      }
-      const useChromiumCanvasKit = supportsChromiumCanvasKit && (options.canvasKitVariant !== "full");
-      const baseUrl = options.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineVersion}`;
-      const canvasKitUrl = useChromiumCanvasKit ? `${baseUrl}/skwasm.js` : `${baseUrl}/chromium/skwasm.js`;
-      const trustedCanvasKitUrl = deps.flutterTT.policy.createScriptURL(canvasKitUrl);
+export const loadSkwasm = (deps, config, browserEnvironment) => {
+    return new Promise((resolve, reject) => {
+      const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineVersion}`;
+      const skwasmUrl = `${baseUrl}/skwasm.js`;
+      const trustedSkwasmUrl = deps.flutterTT.policy.createScriptURL(skwasmUrl);
       const script = document.createElement("script");
-      script.src = trustedCanvasKitUrl;
+      script.src = trustedSkwasmUrl;
       script.addEventListener('load', async () => {
         try {
-          const canvasKit = await CanvasKitInit();
-          window.flutterCanvasKit = canvasKit;
-          resolve(canvasKit);  
+          const skwasmInstance = await skwasm();
+          resolve(skwasmInstance);
         } catch (e) {
           reject(e);
         }
@@ -26,8 +20,7 @@ export const loadSkwasm = (deps, options, browserEnvironment) => {
       script.addEventListener('error', (e) => {
         reject(e);
       });
-      document.body.appendChild(script);
+      document.head.appendChild(script);
     });
-    return window.flutterCanvasKitLoaded;
   }
   
\ No newline at end of file
diff --git a/lib/web_ui/lib/src/engine/canvaskit/renderer.dart b/lib/web_ui/lib/src/engine/canvaskit/renderer.dart
index 15a658b9646ea..0830496ae4d02 100644
--- a/lib/web_ui/lib/src/engine/canvaskit/renderer.dart
+++ b/lib/web_ui/lib/src/engine/canvaskit/renderer.dart
@@ -64,14 +64,11 @@ class CanvasKitRenderer implements Renderer {
   Future<void> initialize() async {
     _initialized ??= () async {
       if (windowFlutterCanvasKit != null) {
-        print('ALREADY LOADED');
         canvasKit = windowFlutterCanvasKit!;
       } else if (windowFlutterCanvasKitLoaded != null) {
-        print('PRELOAD');
         // CanvasKit is being preloaded by flutter.js. Wait for it to complete.
         canvasKit = await promiseToFuture<CanvasKit>(windowFlutterCanvasKitLoaded!);
       } else {
-        print('LOAD OURSELVES');
         canvasKit = await downloadCanvasKit();
         windowFlutterCanvasKit = canvasKit;
       }
diff --git a/lib/web_ui/test/canvaskit/hot_restart_test.dart b/lib/web_ui/test/canvaskit/hot_restart_test.dart
index b032f532e31b7..3ee6903857c44 100644
--- a/lib/web_ui/test/canvaskit/hot_restart_test.dart
+++ b/lib/web_ui/test/canvaskit/hot_restart_test.dart
@@ -12,8 +12,6 @@ void main() {
 
 void testMain() {
   test('CanvasKit reuses the instance already set on `window`', () async {
-    expect(windowFlutterCanvasKit, isNull);
-
     // First initialization should make CanvasKit available through `window`.
     await renderer.initialize();
     expect(windowFlutterCanvasKit, isNotNull);
diff --git a/lib/web_ui/test/canvaskit/initialization/services_vs_ui_test.dart b/lib/web_ui/test/canvaskit/initialization/services_vs_ui_test.dart
index 0cfd55a178a11..709b88aff9a92 100644
--- a/lib/web_ui/test/canvaskit/initialization/services_vs_ui_test.dart
+++ b/lib/web_ui/test/canvaskit/initialization/services_vs_ui_test.dart
@@ -16,7 +16,6 @@ void testMain() {
   test('services are initalized separately from UI', () async {
     final JsFlutterConfiguration? config = await bootstrapAndExtractConfig();
     expect(scheduleFrameCallback, isNull);
-    expect(windowFlutterCanvasKit, isNull);
 
     expect(findGlassPane(), isNull);
     expect(RawKeyboard.instance, isNull);

From 4267ee2aa3ff5a9b0c5f427c74b3cf63dccb0f09 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 14 Dec 2023 09:13:50 -0800
Subject: [PATCH 07/33] Remove hack.

---
 lib/web_ui/dev/test_platform.dart | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/web_ui/dev/test_platform.dart b/lib/web_ui/dev/test_platform.dart
index 1b437b7374efb..209546d0f0876 100644
--- a/lib/web_ui/dev/test_platform.dart
+++ b/lib/web_ui/dev/test_platform.dart
@@ -156,7 +156,7 @@ class BrowserPlatform extends PlatformPlugin {
   Uri get url => server.url.resolve('/');
 
   bool get isWasm => suite.testBundle.compileConfig.compiler == Compiler.dart2wasm;
-  bool get needsCrossOriginIsolated => true; //isWasm && suite.testBundle.compileConfig.renderer == Renderer.skwasm;
+  bool get needsCrossOriginIsolated => isWasm && suite.testBundle.compileConfig.renderer == Renderer.skwasm;
 
   /// A [OneOffHandler] for servicing WebSocket connections for
   /// [BrowserManager]s.

From 0103f5ef1ea4c24b0a4ffaf0dae4bcdf3170ed94 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 14 Dec 2023 09:44:27 -0800
Subject: [PATCH 08/33] Fix browsers without Trusted Types.

---
 lib/web_ui/flutter_js/src/canvaskit_loader.js | 8 +++++---
 lib/web_ui/flutter_js/src/skwasm_loader.js    | 8 +++++---
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/lib/web_ui/flutter_js/src/canvaskit_loader.js b/lib/web_ui/flutter_js/src/canvaskit_loader.js
index c1d8ce2ce093b..012254c089893 100644
--- a/lib/web_ui/flutter_js/src/canvaskit_loader.js
+++ b/lib/web_ui/flutter_js/src/canvaskit_loader.js
@@ -10,10 +10,12 @@ export const loadCanvasKit = (deps, config, browserEnvironment) => {
     }
     const useChromiumCanvasKit = supportsChromiumCanvasKit && (config.canvasKitVariant !== "full");
     const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineVersion}`;
-    const canvasKitUrl = useChromiumCanvasKit ? `${baseUrl}/canvaskit.js` : `${baseUrl}/chromium/canvaskit.js`;
-    const trustedCanvasKitUrl = deps.flutterTT.policy.createScriptURL(canvasKitUrl);
+    let canvasKitUrl = useChromiumCanvasKit ? `${baseUrl}/chromium/canvaskit.js` : `${baseUrl}/canvaskit.js`;
+    if (deps.flutterTT.policy) {
+      canvasKitUrl = deps.flutterTT.policy.createScriptURL(canvasKitUrl);
+    }
     const script = document.createElement("script");
-    script.src = trustedCanvasKitUrl;
+    script.src = canvasKitUrl;
     script.addEventListener('load', async () => {
       try {
         const canvasKit = await CanvasKitInit();
diff --git a/lib/web_ui/flutter_js/src/skwasm_loader.js b/lib/web_ui/flutter_js/src/skwasm_loader.js
index b826d06ab44e1..af20d9374b830 100644
--- a/lib/web_ui/flutter_js/src/skwasm_loader.js
+++ b/lib/web_ui/flutter_js/src/skwasm_loader.js
@@ -5,10 +5,12 @@
 export const loadSkwasm = (deps, config, browserEnvironment) => {
     return new Promise((resolve, reject) => {
       const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineVersion}`;
-      const skwasmUrl = `${baseUrl}/skwasm.js`;
-      const trustedSkwasmUrl = deps.flutterTT.policy.createScriptURL(skwasmUrl);
+      let skwasmUrl = `${baseUrl}/skwasm.js`;
+      if (deps.flutterTT.policy) {
+        skwasmUrl = deps.flutterTT.policy.createScriptURL(skwasmUrl);
+      }
       const script = document.createElement("script");
-      script.src = trustedSkwasmUrl;
+      script.src = skwasmUrl;
       script.addEventListener('load', async () => {
         try {
           const skwasmInstance = await skwasm();

From 9abd0443dab9d796adb93304cbd8bacab32cf100 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 14 Dec 2023 10:08:48 -0800
Subject: [PATCH 09/33] Update licenses golden.

---
 ci/licenses_golden/licenses_flutter | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index 611f58c269881..417377f94196a 100644
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -5787,7 +5787,14 @@ ORIGIN: ../../../flutter/lib/ui/window/pointer_data_packet_converter.cc + ../../
 ORIGIN: ../../../flutter/lib/ui/window/pointer_data_packet_converter.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/ui/window/viewport_metrics.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/ui/window/viewport_metrics.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/browser_environment.js + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/canvaskit_loader.js + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/entrypoint_loader.js + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/flutter.js + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/loader.js + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/service_worker_loader.js + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/skwasm_loader.js + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/trusted_types.js + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/annotations.dart + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/canvas.dart + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/channel_buffers.dart + ../../../flutter/LICENSE
@@ -8600,7 +8607,15 @@ FILE: ../../../flutter/lib/ui/window/pointer_data_packet_converter.cc
 FILE: ../../../flutter/lib/ui/window/pointer_data_packet_converter.h
 FILE: ../../../flutter/lib/ui/window/viewport_metrics.cc
 FILE: ../../../flutter/lib/ui/window/viewport_metrics.h
+FILE: ../../../flutter/lib/web_ui/flutter_js/src/browser_environment.js
+FILE: ../../../flutter/lib/web_ui/flutter_js/src/canvaskit_loader.js
+FILE: ../../../flutter/lib/web_ui/flutter_js/src/entrypoint_loader.js
 FILE: ../../../flutter/lib/web_ui/flutter_js/src/flutter.js
+FILE: ../../../flutter/lib/web_ui/flutter_js/src/loader.js
+FILE: ../../../flutter/lib/web_ui/flutter_js/src/service_worker_loader.js
+FILE: ../../../flutter/lib/web_ui/flutter_js/src/skwasm_loader.js
+FILE: ../../../flutter/lib/web_ui/flutter_js/src/trusted_types.js
+FILE: ../../../flutter/lib/web_ui/flutter_js/src/types.d.ts
 FILE: ../../../flutter/lib/web_ui/lib/annotations.dart
 FILE: ../../../flutter/lib/web_ui/lib/canvas.dart
 FILE: ../../../flutter/lib/web_ui/lib/channel_buffers.dart

From 1898e0e9e5aec1c8616b14d2a621aa171d03e179 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 14 Dec 2023 10:15:20 -0800
Subject: [PATCH 10/33] Remove old test harnesses.

---
 lib/web_ui/dev/test_dart2js.js   | 76 --------------------------
 lib/web_ui/dev/test_dart2wasm.js | 93 --------------------------------
 2 files changed, 169 deletions(-)
 delete mode 100644 lib/web_ui/dev/test_dart2js.js
 delete mode 100644 lib/web_ui/dev/test_dart2wasm.js

diff --git a/lib/web_ui/dev/test_dart2js.js b/lib/web_ui/dev/test_dart2js.js
deleted file mode 100644
index 6f24a42a18cba..0000000000000
--- a/lib/web_ui/dev/test_dart2js.js
+++ /dev/null
@@ -1,76 +0,0 @@
-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// This script runs in HTML files and loads and instantiates unit tests
-// for the flutter web engine that are compiled to dart2js. It is based
-// off of the `test/dart.js` script from the `test` dart package.
-
-export const runTest = (configuration) => {
-  // Sends an error message to the server indicating that the script failed to
-  // load.
-  //
-  // This mimics a MultiChannel-formatted message.
-  var sendLoadException = function (message) {
-    window.parent.postMessage({
-      "href": window.location.href,
-      "data": [0, { "type": "loadException", "message": message }],
-      "exception": true,
-    }, window.location.origin);
-  }
-
-  // Listen for dartLoadException events and forward to the server.
-  window.addEventListener('dartLoadException', function (e) {
-    sendLoadException(e.detail);
-  });
-
-  // The basename of the current page.
-  var name = window.location.href.replace(/.*\//, '').replace(/#.*/, '');
-
-  // Find <link rel="x-dart-test">.
-  var links = document.getElementsByTagName("link");
-  var testLinks = [];
-  var length = links.length;
-  for (var i = 0; i < length; ++i) {
-    if (links[i].rel == "x-dart-test") testLinks.push(links[i]);
-  }
-
-  if (testLinks.length != 1) {
-    sendLoadException(
-      'Expected exactly 1 <link rel="x-dart-test"> in ' + name + ', found ' +
-      testLinks.length + '.');
-    return;
-  }
-
-  var link = testLinks[0];
-
-  if (link.href == '') {
-    sendLoadException(
-      'Expected <link rel="x-dart-test"> in ' + name + ' to have an "href" ' +
-      'attribute.');
-    return;
-  }
-
-  _flutter.buildConfig = {
-    builds: [{
-      compileTarget: "dart2js",
-      renderer: "canvaskit",
-      url: link.href + '.browser_test.dart.js',
-    }]
-  };
-
-  try {
-    window._flutter.loader.load({
-      options: configuration,
-      entrypointUrl: link.href + '.browser_test.dart.js',
-      onEntrypointLoaded: function(engineInitializer) {
-        engineInitializer.initializeEngine(configuration).then(function(appRunner) {
-          appRunner.runApp();
-        });
-      }
-    });
-  } catch (exception) {
-    const message = `Failed to bootstrap unit test: ${exception}`;
-    sendLoadException(message);
-  }
-};
diff --git a/lib/web_ui/dev/test_dart2wasm.js b/lib/web_ui/dev/test_dart2wasm.js
deleted file mode 100644
index e1d1c32c164f9..0000000000000
--- a/lib/web_ui/dev/test_dart2wasm.js
+++ /dev/null
@@ -1,93 +0,0 @@
-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// This script runs in HTML files and loads and instantiates dart unit tests
-// that are compiled to WebAssembly. It is based off of the `test/dart.js`
-// script from the `test` dart package.
-
-window.onload = async function () {
-  // Sends an error message to the server indicating that the script failed to
-  // load.
-  //
-  // This mimics a MultiChannel-formatted message.
-  var sendLoadException = function (message) {
-    window.parent.postMessage({
-      "href": window.location.href,
-      "data": [0, { "type": "loadException", "message": message }],
-      "exception": true,
-    }, window.location.origin);
-  }
-
-  // Listen for dartLoadException events and forward to the server.
-  window.addEventListener('dartLoadException', function (e) {
-    sendLoadException(e.detail);
-  });
-
-  // The basename of the current page.
-  var name = window.location.href.replace(/.*\//, '').replace(/#.*/, '');
-
-  // Find <link rel="x-dart-test">.
-  var links = document.getElementsByTagName("link");
-  var testLinks = [];
-  var length = links.length;
-  for (var i = 0; i < length; ++i) {
-    if (links[i].rel == "x-dart-test") testLinks.push(links[i]);
-  }
-
-  if (testLinks.length != 1) {
-    sendLoadException(
-      'Expected exactly 1 <link rel="x-dart-test"> in ' + name + ', found ' +
-      testLinks.length + '.');
-    return;
-  }
-
-  var link = testLinks[0];
-
-  if (link.href == '') {
-    sendLoadException(
-      'Expected <link rel="x-dart-test"> in ' + name + ' to have an "href" ' +
-      'attribute.');
-    return;
-  }
-
-  let dart2wasm_runtime;
-  let moduleInstance;
-  try {
-    const isSkwasm = link.hasAttribute('skwasm');
-    const imports = isSkwasm ? new Promise((resolve) => {
-      const skwasmScript = document.createElement('script');
-      skwasmScript.src = '/canvaskit/skwasm.js';
-
-      document.body.appendChild(skwasmScript);
-      skwasmScript.addEventListener('load', async () => {
-        const skwasmInstance = await skwasm();
-        window._flutter_skwasmInstance = skwasmInstance;
-        resolve({
-          "skwasm": skwasmInstance.wasmExports,
-          "skwasmWrapper": skwasmInstance,
-          "ffi": {
-            "memory": skwasmInstance.wasmMemory,
-          }
-        });
-      });
-    }) : {};
-
-    let baseName = link.href + '.browser_test.dart';
-    dart2wasm_runtime = await import(baseName + '.mjs');
-    const dartModulePromise = WebAssembly.compileStreaming(fetch(baseName + '.wasm'));
-    moduleInstance = await dart2wasm_runtime.instantiate(dartModulePromise, imports);
-  } catch (exception) {
-    const message = `Failed to fetch and instantiate wasm module: ${exception}`;
-    sendLoadException(message);
-  }
-
-  if (moduleInstance) {
-    try {
-      await dart2wasm_runtime.invoke(moduleInstance);
-    } catch (exception) {
-      const message = `Exception while invoking test: ${exception}`;
-      sendLoadException(message);
-    }
-  }
-};

From 406cd6b3c0a9fccc968989c66bda594c4f04d305 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 14 Dec 2023 11:00:53 -0800
Subject: [PATCH 11/33] Inject engine revision into flutter.js.

---
 lib/web_ui/flutter_js/BUILD.gn                | 18 +++++++++++++++++-
 lib/web_ui/flutter_js/src/canvaskit_loader.js |  4 +++-
 lib/web_ui/flutter_js/src/skwasm_loader.js    |  4 +++-
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/lib/web_ui/flutter_js/BUILD.gn b/lib/web_ui/flutter_js/BUILD.gn
index c49893fd87891..4b84d594643bf 100644
--- a/lib/web_ui/flutter_js/BUILD.gn
+++ b/lib/web_ui/flutter_js/BUILD.gn
@@ -3,11 +3,13 @@
 # found in the LICENSE file.
 
 import("//flutter/build/esbuild/esbuild.gni")
+import("//flutter/shell/version/version.gni")
 import("sources.gni")
 
 group("flutter_js") {
   public_deps = [
     ":flutter_js_bundle",
+    ":flutter_js_engine_version",
     ":flutter_js_sources",
   ]
 }
@@ -18,6 +20,17 @@ copy("flutter_js_sources") {
       [ "$root_out_dir/flutter_web_sdk/flutter_js/{{source_target_relative}}" ]
 }
 
+generated_file("flutter_js_engine_version") {
+  outputs = [ "$root_out_dir/flutter_web_sdk/flutter_js/src/revision.js" ]
+  contents = [
+    "// Copyright 2013 The Flutter Authors. All rights reserved.",
+    "// Use of this source code is governed by a BSD-style license that can be",
+    "// found in the LICENSE file.",
+    "",
+    "export const engineRevision = \"$engine_version\";",
+  ]
+}
+
 esbuild("flutter_js_bundle") {
   entry_point = "$root_out_dir/flutter_web_sdk/flutter_js/src/flutter.js"
   output_bundle = "$root_out_dir/flutter_web_sdk/flutter_js"
@@ -26,5 +39,8 @@ esbuild("flutter_js_bundle") {
   minify = true
   sourcemap = true
 
-  public_deps = [ ":flutter_js_sources" ]
+  public_deps = [
+    ":flutter_js_engine_version",
+    ":flutter_js_sources",
+  ]
 }
diff --git a/lib/web_ui/flutter_js/src/canvaskit_loader.js b/lib/web_ui/flutter_js/src/canvaskit_loader.js
index 012254c089893..847f3593e8a73 100644
--- a/lib/web_ui/flutter_js/src/canvaskit_loader.js
+++ b/lib/web_ui/flutter_js/src/canvaskit_loader.js
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import { engineRevision } from "./revision.js";
+
 export const loadCanvasKit = (deps, config, browserEnvironment) => {
   window.flutterCanvasKitLoaded = new Promise((resolve, reject) => {
     const supportsChromiumCanvasKit = browserEnvironment.hasChromiumBreakIterators && browserEnvironment.hasImageCodecs;
@@ -9,7 +11,7 @@ export const loadCanvasKit = (deps, config, browserEnvironment) => {
       throw "Chromium CanvasKit variant specifically requested, but unsupported in this browser";
     }
     const useChromiumCanvasKit = supportsChromiumCanvasKit && (config.canvasKitVariant !== "full");
-    const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineVersion}`;
+    const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}`;
     let canvasKitUrl = useChromiumCanvasKit ? `${baseUrl}/chromium/canvaskit.js` : `${baseUrl}/canvaskit.js`;
     if (deps.flutterTT.policy) {
       canvasKitUrl = deps.flutterTT.policy.createScriptURL(canvasKitUrl);
diff --git a/lib/web_ui/flutter_js/src/skwasm_loader.js b/lib/web_ui/flutter_js/src/skwasm_loader.js
index af20d9374b830..2bfb8e3f0803b 100644
--- a/lib/web_ui/flutter_js/src/skwasm_loader.js
+++ b/lib/web_ui/flutter_js/src/skwasm_loader.js
@@ -2,9 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import { engineRevision } from "./revision.js";
+
 export const loadSkwasm = (deps, config, browserEnvironment) => {
     return new Promise((resolve, reject) => {
-      const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineVersion}`;
+      const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}`;
       let skwasmUrl = `${baseUrl}/skwasm.js`;
       if (deps.flutterTT.policy) {
         skwasmUrl = deps.flutterTT.policy.createScriptURL(skwasmUrl);

From 7142f19f758e4fac0d0386b07d1c0580542acff5 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 14 Dec 2023 15:13:02 -0800
Subject: [PATCH 12/33] Don't copy nonexistent bootstrap scripts anymore.

---
 lib/web_ui/dev/steps/copy_artifacts_step.dart | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/lib/web_ui/dev/steps/copy_artifacts_step.dart b/lib/web_ui/dev/steps/copy_artifacts_step.dart
index fa63d91761032..b02f6f49e4c8b 100644
--- a/lib/web_ui/dev/steps/copy_artifacts_step.dart
+++ b/lib/web_ui/dev/steps/copy_artifacts_step.dart
@@ -33,7 +33,6 @@ class CopyArtifactsStep implements PipelineStep {
   @override
   Future<void> run() async {
     await environment.webTestsArtifactsDir.create(recursive: true);
-    await copyTestBootstrapScripts();
     await buildHostPage();
     await copyTestFonts();
     await copySkiaTestImages();
@@ -52,23 +51,6 @@ class CopyArtifactsStep implements PipelineStep {
     }
   }
 
-  Future<void> copyTestBootstrapScripts() async {
-    for (final String filename in <String>[
-      'test_dart2js.js',
-      'test_dart2wasm.js',
-    ]) {
-      final io.File sourceFile = io.File(pathlib.join(
-        environment.webUiDevDir.path,
-        filename,
-      ));
-      final io.File targetFile = io.File(pathlib.join(
-        environment.webTestsArtifactsDir.path,
-        filename,
-      ));
-      await sourceFile.copy(targetFile.path);
-    }
-  }
-
   Future<void> copyTestFonts() async {
     const Map<String, String> testFonts = <String, String>{
       'Ahem': 'ahem.ttf',

From 770a89daa11e16c9126124b75c8a2276880036e0 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 14 Dec 2023 17:17:18 -0800
Subject: [PATCH 13/33] Remove skwasm_stub tests. No longer pertinent.

---
 lib/web_ui/test/felt_config.yaml            | 13 ----------
 lib/web_ui/test/skwasm_stub/smoke_test.dart | 28 ---------------------
 2 files changed, 41 deletions(-)
 delete mode 100644 lib/web_ui/test/skwasm_stub/smoke_test.dart

diff --git a/lib/web_ui/test/felt_config.yaml b/lib/web_ui/test/felt_config.yaml
index 6cc145be6a3cc..1bf13914581e0 100644
--- a/lib/web_ui/test/felt_config.yaml
+++ b/lib/web_ui/test/felt_config.yaml
@@ -42,11 +42,6 @@ test-sets:
   - name: ui
     directory: ui
 
-  # This just has a single test that makes sure the skwasm stub renderer is
-  # included when compiling to JS
-  - name: skwasm_stub
-    directory: skwasm_stub
-
 test-bundles:
   - name: dart2js-html-engine
     test-set: engine
@@ -68,10 +63,6 @@ test-bundles:
     test-set: ui
     compile-config: dart2js-canvaskit
 
-  - name: dart2js-skwasm-skwasm_stub
-    test-set: skwasm_stub
-    compile-config: dart2js-skwasm
-
   - name: dart2wasm-html-engine
     test-set: engine
     compile-config: dart2wasm-html
@@ -144,10 +135,6 @@ test-suites:
     run-config: chrome
     artifact-deps: [ canvaskit_chromium ]
 
-  - name: chrome-dart2js-skwasm-skwasm_stub
-    test-bundle: dart2js-skwasm-skwasm_stub
-    run-config: chrome
-
   - name: chrome-full-dart2js-canvaskit-canvaskit
     test-bundle: dart2js-canvaskit-canvaskit
     run-config: chrome-full
diff --git a/lib/web_ui/test/skwasm_stub/smoke_test.dart b/lib/web_ui/test/skwasm_stub/smoke_test.dart
deleted file mode 100644
index 7361d9c283c65..0000000000000
--- a/lib/web_ui/test/skwasm_stub/smoke_test.dart
+++ /dev/null
@@ -1,28 +0,0 @@
-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-@TestOn('chrome || safari || firefox')
-library;
-
-import 'dart:async';
-
-import 'package:test/bootstrap/browser.dart';
-import 'package:test/test.dart';
-import 'package:ui/src/engine/renderer.dart';
-import 'package:ui/src/engine/skwasm/skwasm_stub/renderer.dart';
-
-void main() {
-  internalBootstrapBrowserTest(() => testMain);
-}
-
-Future<void> testMain() async {
-  group('Skwasm stub tests', () {
-    test('Skwasm stub renderer throws', () {
-      expect(renderer, isA<SkwasmRenderer>());
-      expect(() {
-        renderer.initialize();
-      }, throwsUnimplementedError);
-    });
-  });
-}

From 111fdd915bb2bc6ed0eb288f0f67d97580287163 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Fri, 15 Dec 2023 08:41:26 -0800
Subject: [PATCH 14/33] Adjust builder json.

---
 ci/builders/linux_web_engine.json | 94 -------------------------------
 1 file changed, 94 deletions(-)

diff --git a/ci/builders/linux_web_engine.json b/ci/builders/linux_web_engine.json
index 9dc023b4458b4..b91e62411d45d 100644
--- a/ci/builders/linux_web_engine.json
+++ b/ci/builders/linux_web_engine.json
@@ -178,28 +178,6 @@
         ]
       }
     },
-    {
-      "name": "web_tests/test_bundles/dart2js-skwasm-skwasm_stub",
-      "drone_dimensions": [
-        "device_type=none",
-        "os=Linux"
-      ],
-      "generators": {
-        "tasks": [
-          {
-            "name": "compile bundle dart2js-skwasm-skwasm_stub",
-            "parameters": [
-              "test",
-              "--compile",
-              "--bundle=dart2js-skwasm-skwasm_stub"
-            ],
-            "scripts": [
-              "flutter/lib/web_ui/dev/felt"
-            ]
-          }
-        ]
-      }
-    },
     {
       "name": "web_tests/test_bundles/dart2wasm-html-engine",
       "drone_dimensions": [
@@ -514,42 +492,6 @@
         }
       ]
     },
-    {
-      "name": "Linux run chrome-dart2js-skwasm-skwasm_stub suite",
-      "recipe": "engine_v2/tester_engine",
-      "drone_dimensions": [
-        "device_type=none",
-        "os=Linux"
-      ],
-      "gclient_variables": {
-        "download_android_deps": false
-      },
-      "dependencies": [
-        "web_tests/artifacts",
-        "web_tests/test_bundles/dart2js-skwasm-skwasm_stub"
-      ],
-      "test_dependencies": [
-        {
-          "dependency": "goldctl",
-          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
-        },
-        {
-          "dependency": "chrome_and_driver",
-          "version": "119.0.6045.9"
-        }
-      ],
-      "tasks": [
-        {
-          "name": "run suite chrome-dart2js-skwasm-skwasm_stub",
-          "parameters": [
-            "test",
-            "--run",
-            "--suite=chrome-dart2js-skwasm-skwasm_stub"
-          ],
-          "script": "flutter/lib/web_ui/dev/felt"
-        }
-      ]
-    },
     {
       "name": "Linux run chrome-full-dart2js-canvaskit-canvaskit suite",
       "recipe": "engine_v2/tester_engine",
@@ -1435,42 +1377,6 @@
         }
       ]
     },
-    {
-      "name": "Windows run chrome-dart2js-skwasm-skwasm_stub suite",
-      "recipe": "engine_v2/tester_engine",
-      "drone_dimensions": [
-        "device_type=none",
-        "os=Windows"
-      ],
-      "gclient_variables": {
-        "download_android_deps": false
-      },
-      "dependencies": [
-        "web_tests/artifacts",
-        "web_tests/test_bundles/dart2js-skwasm-skwasm_stub"
-      ],
-      "test_dependencies": [
-        {
-          "dependency": "goldctl",
-          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
-        },
-        {
-          "dependency": "chrome_and_driver",
-          "version": "119.0.6045.9"
-        }
-      ],
-      "tasks": [
-        {
-          "name": "run suite chrome-dart2js-skwasm-skwasm_stub",
-          "parameters": [
-            "test",
-            "--run",
-            "--suite=chrome-dart2js-skwasm-skwasm_stub"
-          ],
-          "script": "flutter/lib/web_ui/dev/felt"
-        }
-      ]
-    },
     {
       "name": "Windows run chrome-full-dart2js-canvaskit-canvaskit suite",
       "recipe": "engine_v2/tester_engine",

From c249d05069446bca5ceaa892c0e3a70ac6367be2 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Fri, 15 Dec 2023 10:19:16 -0800
Subject: [PATCH 15/33] Allow for multiple compile configs.

---
 lib/web_ui/dev/chrome.dart                    | 13 +---
 lib/web_ui/dev/common.dart                    |  3 +-
 lib/web_ui/dev/felt_config.dart               | 23 ++++---
 lib/web_ui/dev/generate_builder_json.dart     |  6 +-
 lib/web_ui/dev/steps/compile_bundle_step.dart | 61 +++++++++++--------
 lib/web_ui/dev/steps/run_suite_step.dart      | 11 ++--
 lib/web_ui/dev/suite_filter.dart              | 22 +++++--
 lib/web_ui/dev/test_platform.dart             | 15 +++--
 lib/web_ui/test/felt_config.yaml              | 22 +++----
 9 files changed, 93 insertions(+), 83 deletions(-)

diff --git a/lib/web_ui/dev/chrome.dart b/lib/web_ui/dev/chrome.dart
index 374d4d61e1646..b209ddfb96dff 100644
--- a/lib/web_ui/dev/chrome.dart
+++ b/lib/web_ui/dev/chrome.dart
@@ -23,14 +23,11 @@ import 'package_lock.dart';
 /// Provides an environment for desktop Chrome.
 class ChromeEnvironment implements BrowserEnvironment {
   ChromeEnvironment({
-    required bool enableWasmGC,
     required bool useDwarf,
-  }) : _enableWasmGC = enableWasmGC,
-       _useDwarf = useDwarf;
+  }) : _useDwarf = useDwarf;
 
   late final BrowserInstallation _installation;
 
-  final bool _enableWasmGC;
   final bool _useDwarf;
 
   @override
@@ -42,7 +39,6 @@ class ChromeEnvironment implements BrowserEnvironment {
       url,
       _installation,
       debug: debug,
-      enableWasmGC: _enableWasmGC,
       useDwarf: _useDwarf
     );
   }
@@ -83,7 +79,6 @@ class Chrome extends Browser {
     Uri url,
     BrowserInstallation installation, {
     required bool debug,
-    required bool enableWasmGC,
     required bool useDwarf,
   }) {
     final Completer<Uri> remoteDebuggerCompleter = Completer<Uri>.sync();
@@ -101,13 +96,7 @@ class Chrome extends Browser {
       final bool isChromeNoSandbox =
           Platform.environment['CHROME_NO_SANDBOX'] == 'true';
       final String dir = await generateUserDirectory(installation, useDwarf);
-      final String jsFlags = enableWasmGC ? <String>[
-        '--experimental-wasm-gc',
-        '--experimental-wasm-stack-switching',
-        '--experimental-wasm-type-reflection',
-      ].join(' ') : '';
       final List<String> args = <String>[
-        if (jsFlags.isNotEmpty) '--js-flags=$jsFlags',
         '--user-data-dir=$dir',
         url.toString(),
         if (!debug)
diff --git a/lib/web_ui/dev/common.dart b/lib/web_ui/dev/common.dart
index 301b9bc05ae81..0eabc3b62eeed 100644
--- a/lib/web_ui/dev/common.dart
+++ b/lib/web_ui/dev/common.dart
@@ -240,12 +240,11 @@ const List<String> kAllBrowserNames = <String>[
 /// The [browserName] matches the browser name passed as the `--browser` option.
 BrowserEnvironment getBrowserEnvironment(
   BrowserName browserName, {
-  required bool enableWasmGC,
   required bool useDwarf,
 }) {
   switch (browserName) {
     case BrowserName.chrome:
-      return ChromeEnvironment(enableWasmGC: enableWasmGC, useDwarf: useDwarf);
+      return ChromeEnvironment(useDwarf: useDwarf);
     case BrowserName.edge:
       return EdgeEnvironment();
     case BrowserName.firefox:
diff --git a/lib/web_ui/dev/felt_config.dart b/lib/web_ui/dev/felt_config.dart
index 6e42e500d2fb1..31f873938a830 100644
--- a/lib/web_ui/dev/felt_config.dart
+++ b/lib/web_ui/dev/felt_config.dart
@@ -32,11 +32,11 @@ class TestSet {
 }
 
 class TestBundle {
-  TestBundle(this.name, this.testSet, this.compileConfig);
+  TestBundle(this.name, this.testSet, this.compileConfigs);
 
   final String name;
   final TestSet testSet;
-  final CompileConfiguration compileConfig;
+  final List<CompileConfiguration> compileConfigs;
 }
 
 enum CanvasKitVariant {
@@ -157,12 +157,16 @@ class FeltConfig {
       if (testSet == null) {
         throw AssertionError('Test set not found with name: `$testSetName` (referenced by test bundle: `$name`)');
       }
-      final String compileConfigName = testBundleYaml['compile-config'] as String;
-      final CompileConfiguration? compileConfig = compileConfigsByName[compileConfigName];
-      if (compileConfig == null) {
-        throw AssertionError('Compile config not found with name: `$compileConfigName` (referenced by test bundle: `$name`)');
+      final dynamic compileConfigsValue = testBundleYaml['compile-configs'];
+      final List<CompileConfiguration> compileConfigs;
+      if (compileConfigsValue is String) {
+        compileConfigs = <CompileConfiguration>[compileConfigsByName[compileConfigsValue]!];
+      } else {
+        compileConfigs = (compileConfigsValue as List<dynamic>).map(
+          (dynamic configName) => compileConfigsByName[configName as String]!
+        ).toList();
       }
-      final TestBundle bundle = TestBundle(name, testSet, compileConfig);
+      final TestBundle bundle = TestBundle(name, testSet, compileConfigs);
       testBundles.add(bundle);
       if (testBundlesByName.containsKey(name)) {
         throw AssertionError('Duplicate test bundle name: $name');
@@ -202,11 +206,6 @@ class FeltConfig {
       if (runConfig == null) {
         throw AssertionError('Run config not found with name: `$runConfigName` (referenced by test suite: `$name`)');
       }
-      if (bundle.compileConfig.renderer == Renderer.canvaskit && runConfig.variant == null) {
-        throw AssertionError(
-            'Run config `$runConfigName` was used with a CanvasKit test bundle `$testBundleName` '
-            'but did not specify a CanvasKit variant (referenced by test suite: `$name`)');
-      }
       bool canvasKit = false;
       bool canvasKitChromium = false;
       bool skwasm = false;
diff --git a/lib/web_ui/dev/generate_builder_json.dart b/lib/web_ui/dev/generate_builder_json.dart
index fe1e6f664a9aa..b2d9a5adc6bd5 100644
--- a/lib/web_ui/dev/generate_builder_json.dart
+++ b/lib/web_ui/dev/generate_builder_json.dart
@@ -120,11 +120,7 @@ Iterable<dynamic> _getAllTestSteps(List<TestSuite> suites) {
       suite.runConfig.browser == BrowserName.safari
     ),
     ..._getTestStepsForPlatform(suites, 'Windows', (TestSuite suite) =>
-      suite.runConfig.browser == BrowserName.chrome &&
-
-      // TODO(jacksongardner): Enable dart2wasm tests on Windows
-      // https://github.com/flutter/flutter/issues/124082
-      suite.testBundle.compileConfig.compiler != Compiler.dart2wasm
+      suite.runConfig.browser == BrowserName.chrome
     ),
   ];
 }
diff --git a/lib/web_ui/dev/steps/compile_bundle_step.dart b/lib/web_ui/dev/steps/compile_bundle_step.dart
index 6601e2fe49e20..b1d86ce8eeb2c 100644
--- a/lib/web_ui/dev/steps/compile_bundle_step.dart
+++ b/lib/web_ui/dev/steps/compile_bundle_step.dart
@@ -61,20 +61,20 @@ class CompileBundleStep implements PipelineStep {
       .toList();
   }
 
-  TestCompiler _createCompiler() {
-    switch (bundle.compileConfig.compiler) {
+  TestCompiler _createCompiler(CompileConfiguration config) {
+    switch (config.compiler) {
       case Compiler.dart2js:
         return Dart2JSCompiler(
           testSetDirectory,
           outputBundleDirectory,
-          renderer: bundle.compileConfig.renderer,
+          renderer: config.renderer,
           isVerbose: isVerbose,
         );
       case Compiler.dart2wasm:
         return Dart2WasmCompiler(
           testSetDirectory,
           outputBundleDirectory,
-          renderer: bundle.compileConfig.renderer,
+          renderer: config.renderer,
           isVerbose: isVerbose,
         );
     }
@@ -84,7 +84,9 @@ class CompileBundleStep implements PipelineStep {
   Future<void> run() async {
     print('Compiling test bundle ${bundle.name.ansiMagenta}...');
     final List<FilePath> allTests = _findTestFiles();
-    final TestCompiler compiler = _createCompiler();
+    final List<TestCompiler> compilers = bundle.compileConfigs.map(
+      (CompileConfiguration config) => _createCompiler(config)
+    ).toList();
     final Stopwatch stopwatch = Stopwatch()..start();
     final String testSetDirectoryPath = testSetDirectory.path;
 
@@ -94,26 +96,28 @@ class CompileBundleStep implements PipelineStep {
     }
 
     final List<Future<MapEntry<String, CompileResult>>> pendingResults = <Future<MapEntry<String, CompileResult>>>[];
-    for (final FilePath testFile in allTests) {
-      final String relativePath = pathlib.relative(
-        testFile.absolute,
-        from: testSetDirectoryPath);
-      final Future<MapEntry<String, CompileResult>> result = compilePool.withResource(() async {
-        if (testFiles != null && !testFiles!.contains(testFile)) {
-          return MapEntry<String, CompileResult>(relativePath, CompileResult.filtered);
-        }
-        final bool success = await compiler.compileTest(testFile);
-        const int maxTestNameLength = 80;
-        final String truncatedPath = relativePath.length > maxTestNameLength
-          ? relativePath.replaceRange(maxTestNameLength - 3, relativePath.length, '...')
-          : relativePath;
-        final String expandedPath = truncatedPath.padRight(maxTestNameLength);
-        io.stdout.write('\r  ${success ? expandedPath.ansiGreen : expandedPath.ansiRed}');
-        return success
-          ? MapEntry<String, CompileResult>(relativePath, CompileResult.success)
-          : MapEntry<String, CompileResult>(relativePath, CompileResult.compilationFailure);
-      });
-      pendingResults.add(result);
+    for (final TestCompiler compiler in compilers) {
+      for (final FilePath testFile in allTests) {
+        final String relativePath = pathlib.relative(
+          testFile.absolute,
+          from: testSetDirectoryPath);
+        final Future<MapEntry<String, CompileResult>> result = compilePool.withResource(() async {
+          if (testFiles != null && !testFiles!.contains(testFile)) {
+            return MapEntry<String, CompileResult>(relativePath, CompileResult.filtered);
+          }
+          final bool success = await compiler.compileTest(testFile);
+          const int maxTestNameLength = 80;
+          final String truncatedPath = relativePath.length > maxTestNameLength
+            ? relativePath.replaceRange(maxTestNameLength - 3, relativePath.length, '...')
+            : relativePath;
+          final String expandedPath = truncatedPath.padRight(maxTestNameLength);
+          io.stdout.write('\r  ${success ? expandedPath.ansiGreen : expandedPath.ansiRed}');
+          return success
+            ? MapEntry<String, CompileResult>(relativePath, CompileResult.success)
+            : MapEntry<String, CompileResult>(relativePath, CompileResult.compilationFailure);
+        });
+        pendingResults.add(result);
+      }
     }
     final Map<String, CompileResult> results = Map<String, CompileResult>.fromEntries(await Future.wait(pendingResults));
     stopwatch.stop();
@@ -121,8 +125,11 @@ class CompileBundleStep implements PipelineStep {
     final String resultsJson = const JsonEncoder.withIndent('  ').convert(<String, dynamic>{
       'name': bundle.name,
       'directory': bundle.testSet.directory,
-      'compiler': bundle.compileConfig.compiler.name,
-      'renderer': bundle.compileConfig.renderer.name,
+      'builds': bundle.compileConfigs.map(
+        (CompileConfiguration config) => <String, dynamic>{
+          'compiler': config.compiler.name,
+          'renderer': config.renderer.name,
+        }).toList(),
       'compileTimeInMs': stopwatch.elapsedMilliseconds,
       'results': results.map((String k, CompileResult v) => MapEntry<String, String>(k, v.name)),
     });
diff --git a/lib/web_ui/dev/steps/run_suite_step.dart b/lib/web_ui/dev/steps/run_suite_step.dart
index adb9a12d8bb4b..a19abdc5302c9 100644
--- a/lib/web_ui/dev/steps/run_suite_step.dart
+++ b/lib/web_ui/dev/steps/run_suite_step.dart
@@ -49,8 +49,6 @@ class RunSuiteStep implements PipelineStep {
   /// Require Skia Gold to be available and reachable.
   final bool requireSkiaGold;
 
-  bool get isWasm => suite.testBundle.compileConfig.compiler == Compiler.dart2wasm;
-
   @override
   String get description => 'run_suite';
 
@@ -65,7 +63,6 @@ class RunSuiteStep implements PipelineStep {
     _prepareTestResultsDirectory();
     final BrowserEnvironment browserEnvironment = getBrowserEnvironment(
       suite.runConfig.browser,
-      enableWasmGC: isWasm,
       useDwarf: useDwarf,
     );
     await browserEnvironment.prepare();
@@ -177,12 +174,18 @@ class RunSuiteStep implements PipelineStep {
   }
 
   Future<SkiaGoldClient?> _createSkiaClient() async {
-    final Renderer renderer = suite.testBundle.compileConfig.renderer;
+    if (suite.testBundle.compileConfigs.length > 1) {
+      // Multiple compile configs are only used for our fallback tests, which
+      // do not collect goldens.
+      return null;
+    }
+    final Renderer renderer = suite.testBundle.compileConfigs.first.renderer;
     final CanvasKitVariant? variant = suite.runConfig.variant;
     final io.Directory workDirectory = getSkiaGoldDirectoryForSuite(suite);
     if (workDirectory.existsSync()) {
       workDirectory.deleteSync(recursive: true);
     }
+    final bool isWasm = suite.testBundle.compileConfigs.first.compiler == Compiler.dart2wasm;
     final SkiaGoldClient skiaClient = SkiaGoldClient(
       workDirectory,
       dimensions: <String, String> {
diff --git a/lib/web_ui/dev/suite_filter.dart b/lib/web_ui/dev/suite_filter.dart
index 25b566a1ff18d..91f26610bbb87 100644
--- a/lib/web_ui/dev/suite_filter.dart
+++ b/lib/web_ui/dev/suite_filter.dart
@@ -70,18 +70,28 @@ class FileFilter extends BundleNameFilter {
   }
 }
 
-class CompilerFilter extends AllowListSuiteFilter<Compiler> {
-  CompilerFilter({required super.allowList});
+class CompilerFilter extends SuiteFilter {
+  CompilerFilter({required this.allowList});
+
+  final Set<Compiler> allowList;
 
   @override
-  Compiler getAttributeForSuite(TestSuite suite) => suite.testBundle.compileConfig.compiler;
+  SuiteFilterResult filterSuite(TestSuite suite) => suite.testBundle.compileConfigs.any(
+    (CompileConfiguration config) => allowList.contains(config.compiler)
+  ) ? SuiteFilterResult.accepted()
+    : SuiteFilterResult.rejected('Selected compilers not used in suite.');
 }
 
-class RendererFilter extends AllowListSuiteFilter<Renderer> {
-  RendererFilter({required super.allowList});
+class RendererFilter extends SuiteFilter {
+  RendererFilter({required this.allowList});
+
+  final Set<Renderer> allowList;
 
   @override
-  Renderer getAttributeForSuite(TestSuite suite) => suite.testBundle.compileConfig.renderer;
+  SuiteFilterResult filterSuite(TestSuite suite) => suite.testBundle.compileConfigs.any(
+    (CompileConfiguration config) => allowList.contains(config.renderer)
+  ) ? SuiteFilterResult.accepted()
+    : SuiteFilterResult.rejected('Selected renderers not used in suite.');
 }
 
 class CanvasKitVariantFilter extends AllowListSuiteFilter<CanvasKitVariant> {
diff --git a/lib/web_ui/dev/test_platform.dart b/lib/web_ui/dev/test_platform.dart
index 209546d0f0876..b91c35408393d 100644
--- a/lib/web_ui/dev/test_platform.dart
+++ b/lib/web_ui/dev/test_platform.dart
@@ -155,8 +155,9 @@ class BrowserPlatform extends PlatformPlugin {
   /// The URL for this server.
   Uri get url => server.url.resolve('/');
 
-  bool get isWasm => suite.testBundle.compileConfig.compiler == Compiler.dart2wasm;
-  bool get needsCrossOriginIsolated => isWasm && suite.testBundle.compileConfig.renderer == Renderer.skwasm;
+  bool get needsCrossOriginIsolated => suite.testBundle.compileConfigs.any(
+    (CompileConfiguration config) => config.renderer == Renderer.skwasm
+  );
 
   /// A [OneOffHandler] for servicing WebSocket connections for
   /// [BrowserManager]s.
@@ -551,12 +552,15 @@ class BrowserPlatform extends PlatformPlugin {
       final String test = '${p.withoutExtension(path)}.dart';
       final String scriptBase = htmlEscape.convert(p.basename(test));
 
+      final String buildConfigsString = suite.testBundle.compileConfigs.map(
+        (CompileConfiguration config) => _makeBuildConfigString(scriptBase, config)
+      ).join(',\n');
       final String bootstrapScript = '''
 <script src="/flutter_js/flutter.js"></script>
 <script>
   _flutter.buildConfig = {
     builds: [
-      ${_makeBuildConfigString(scriptBase, suite.testBundle.compileConfig)}
+      $buildConfigsString
     ]
   };
   _flutter.loader.load({
@@ -651,13 +655,16 @@ class BrowserPlatform extends PlatformPlugin {
           'debug': isDebug.toString()
         });
 
+    final bool hasSourceMaps = suite.testBundle.compileConfigs.any(
+      (CompileConfiguration config) => config.compiler == Compiler.dart2js
+    );
     final Future<BrowserManager?> future = BrowserManager.start(
       browserEnvironment: browserEnvironment,
       url: hostUrl,
       future: completer.future,
       packageConfig: packageConfig,
       debug: isDebug,
-      sourceMapDirectory: isWasm ? null : getBundleBuildDirectory(suite.testBundle),
+      sourceMapDirectory: hasSourceMaps ? getBundleBuildDirectory(suite.testBundle) : null,
     );
 
     // Store null values for browsers that error out so we know not to load them
diff --git a/lib/web_ui/test/felt_config.yaml b/lib/web_ui/test/felt_config.yaml
index 1bf13914581e0..79f94905f5cc1 100644
--- a/lib/web_ui/test/felt_config.yaml
+++ b/lib/web_ui/test/felt_config.yaml
@@ -45,47 +45,47 @@ test-sets:
 test-bundles:
   - name: dart2js-html-engine
     test-set: engine
-    compile-config: dart2js-html
+    compile-configs: dart2js-html
 
   - name: dart2js-html-html
     test-set: html
-    compile-config: dart2js-html
+    compile-configs: dart2js-html
 
   - name: dart2js-html-ui
     test-set: ui
-    compile-config: dart2js-html
+    compile-configs: dart2js-html
 
   - name: dart2js-canvaskit-canvaskit
     test-set: canvaskit
-    compile-config: dart2js-canvaskit
+    compile-configs: dart2js-canvaskit
 
   - name: dart2js-canvaskit-ui
     test-set: ui
-    compile-config: dart2js-canvaskit
+    compile-configs: dart2js-canvaskit
 
   - name: dart2wasm-html-engine
     test-set: engine
-    compile-config: dart2wasm-html
+    compile-configs: dart2wasm-html
 
   - name: dart2wasm-html-html
     test-set: html
-    compile-config: dart2wasm-html
+    compile-configs: dart2wasm-html
 
   - name: dart2wasm-html-ui
     test-set: ui
-    compile-config: dart2wasm-html
+    compile-configs: dart2wasm-html
 
   - name: dart2wasm-canvaskit-canvaskit
     test-set: canvaskit
-    compile-config: dart2wasm-canvaskit
+    compile-configs: dart2wasm-canvaskit
 
   - name: dart2wasm-canvaskit-ui
     test-set: ui
-    compile-config: dart2wasm-canvaskit
+    compile-configs: dart2wasm-canvaskit
 
   - name: dart2wasm-skwasm-ui
     test-set: ui
-    compile-config: dart2wasm-skwasm
+    compile-configs: dart2wasm-skwasm
 
 run-configs:
   - name: chrome

From 06b27a577cf99856a2966ead9d2dc2b516b494c0 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Fri, 15 Dec 2023 10:50:28 -0800
Subject: [PATCH 16/33] Add test for build fallbacks.

---
 ci/builders/linux_web_engine.json             | 451 ++++++++++++++++++
 lib/web_ui/test/fallbacks/fallbacks_test.dart |  31 ++
 lib/web_ui/test/felt_config.yaml              |  25 +
 3 files changed, 507 insertions(+)
 create mode 100644 lib/web_ui/test/fallbacks/fallbacks_test.dart

diff --git a/ci/builders/linux_web_engine.json b/ci/builders/linux_web_engine.json
index b91e62411d45d..138e42565327b 100644
--- a/ci/builders/linux_web_engine.json
+++ b/ci/builders/linux_web_engine.json
@@ -309,6 +309,28 @@
           }
         ]
       }
+    },
+    {
+      "name": "web_tests/test_bundles/fallbacks",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Linux"
+      ],
+      "generators": {
+        "tasks": [
+          {
+            "name": "compile bundle fallbacks",
+            "parameters": [
+              "test",
+              "--compile",
+              "--bundle=fallbacks"
+            ],
+            "scripts": [
+              "flutter/lib/web_ui/dev/felt"
+            ]
+          }
+        ]
+      }
     }
   ],
   "tests": [
@@ -1032,6 +1054,78 @@
         }
       ]
     },
+    {
+      "name": "Linux run chrome-fallbacks suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Linux"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/fallbacks"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "chrome_and_driver",
+          "version": "119.0.6045.9"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite chrome-fallbacks",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=chrome-fallbacks"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
+    {
+      "name": "Linux run firefox-fallbacks suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Linux"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/fallbacks"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "firefox",
+          "version": "version:106.0"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite firefox-fallbacks",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=firefox-fallbacks"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
     {
       "name": "Mac run safari-dart2js-html-engine suite",
       "recipe": "engine_v2/tester_engine",
@@ -1197,6 +1291,39 @@
         }
       ]
     },
+    {
+      "name": "Mac run safari-fallbacks suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Mac-13",
+        "cpu=arm64"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/fallbacks"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite safari-fallbacks",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=safari-fallbacks"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
     {
       "name": "Windows run chrome-dart2js-html-engine suite",
       "recipe": "engine_v2/tester_engine",
@@ -1448,6 +1575,330 @@
           "script": "flutter/lib/web_ui/dev/felt"
         }
       ]
+    },
+    {
+      "name": "Windows run chrome-dart2wasm-html-engine suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Windows"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/dart2wasm-html-engine"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "chrome_and_driver",
+          "version": "119.0.6045.9"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite chrome-dart2wasm-html-engine",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=chrome-dart2wasm-html-engine"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
+    {
+      "name": "Windows run chrome-dart2wasm-html-html suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Windows"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/dart2wasm-html-html"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "chrome_and_driver",
+          "version": "119.0.6045.9"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite chrome-dart2wasm-html-html",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=chrome-dart2wasm-html-html"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
+    {
+      "name": "Windows run chrome-dart2wasm-html-ui suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Windows"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/dart2wasm-html-ui"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "chrome_and_driver",
+          "version": "119.0.6045.9"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite chrome-dart2wasm-html-ui",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=chrome-dart2wasm-html-ui"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
+    {
+      "name": "Windows run chrome-dart2wasm-canvaskit-canvaskit suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Windows"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/dart2wasm-canvaskit-canvaskit"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "chrome_and_driver",
+          "version": "119.0.6045.9"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite chrome-dart2wasm-canvaskit-canvaskit",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=chrome-dart2wasm-canvaskit-canvaskit"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
+    {
+      "name": "Windows run chrome-dart2wasm-canvaskit-ui suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Windows"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/dart2wasm-canvaskit-ui"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "chrome_and_driver",
+          "version": "119.0.6045.9"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite chrome-dart2wasm-canvaskit-ui",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=chrome-dart2wasm-canvaskit-ui"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
+    {
+      "name": "Windows run chrome-dart2wasm-skwasm-ui suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Windows"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/dart2wasm-skwasm-ui"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "chrome_and_driver",
+          "version": "119.0.6045.9"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite chrome-dart2wasm-skwasm-ui",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=chrome-dart2wasm-skwasm-ui"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
+    {
+      "name": "Windows run chrome-full-dart2wasm-canvaskit-canvaskit suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Windows"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/dart2wasm-canvaskit-canvaskit"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "chrome_and_driver",
+          "version": "119.0.6045.9"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite chrome-full-dart2wasm-canvaskit-canvaskit",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=chrome-full-dart2wasm-canvaskit-canvaskit"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
+    {
+      "name": "Windows run chrome-full-dart2wasm-canvaskit-ui suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Windows"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/dart2wasm-canvaskit-ui"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "chrome_and_driver",
+          "version": "119.0.6045.9"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite chrome-full-dart2wasm-canvaskit-ui",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=chrome-full-dart2wasm-canvaskit-ui"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
+    },
+    {
+      "name": "Windows run chrome-fallbacks suite",
+      "recipe": "engine_v2/tester_engine",
+      "drone_dimensions": [
+        "device_type=none",
+        "os=Windows"
+      ],
+      "gclient_variables": {
+        "download_android_deps": false
+      },
+      "dependencies": [
+        "web_tests/artifacts",
+        "web_tests/test_bundles/fallbacks"
+      ],
+      "test_dependencies": [
+        {
+          "dependency": "goldctl",
+          "version": "git_revision:720a542f6fe4f92922c3b8f0fdcc4d2ac6bb83cd"
+        },
+        {
+          "dependency": "chrome_and_driver",
+          "version": "119.0.6045.9"
+        }
+      ],
+      "tasks": [
+        {
+          "name": "run suite chrome-fallbacks",
+          "parameters": [
+            "test",
+            "--run",
+            "--suite=chrome-fallbacks"
+          ],
+          "script": "flutter/lib/web_ui/dev/felt"
+        }
+      ]
     }
   ]
 }
\ No newline at end of file
diff --git a/lib/web_ui/test/fallbacks/fallbacks_test.dart b/lib/web_ui/test/fallbacks/fallbacks_test.dart
new file mode 100644
index 0000000000000..da9ac9a64fe1e
--- /dev/null
+++ b/lib/web_ui/test/fallbacks/fallbacks_test.dart
@@ -0,0 +1,31 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+
+import 'package:test/bootstrap/browser.dart';
+import 'package:test/test.dart';
+import 'package:ui/src/engine.dart';
+
+import '../common/test_initialization.dart';
+import '../ui/utils.dart';
+
+void main() {
+  internalBootstrapBrowserTest(() => testMain);
+}
+
+Future<void> testMain() async {
+  setUpUnitTests(
+    setUpTestViewDimensions: false,
+  );
+
+  test('bootstrapper selects correct builds', () {
+    if (browserEngine == BrowserEngine.blink) {
+      expect(isWasm, isTrue);
+      expect(isSkwasm, isTrue);
+    } else {
+      expect(isWasm, isFalse);
+      expect(isCanvasKit, isTrue);
+    }
+  });
+}
diff --git a/lib/web_ui/test/felt_config.yaml b/lib/web_ui/test/felt_config.yaml
index 79f94905f5cc1..2e20a355c3244 100644
--- a/lib/web_ui/test/felt_config.yaml
+++ b/lib/web_ui/test/felt_config.yaml
@@ -42,6 +42,10 @@ test-sets:
   - name: ui
     directory: ui
 
+  # Tests for fallback functionality between build variants
+  - name: fallbacks
+    directory: fallbacks
+
 test-bundles:
   - name: dart2js-html-engine
     test-set: engine
@@ -87,6 +91,12 @@ test-bundles:
     test-set: ui
     compile-configs: dart2wasm-skwasm
 
+  - name: fallbacks
+    test-set: fallbacks
+    compile-configs:
+      - dart2wasm-skwasm
+      - dart2js-canvaskit
+
 run-configs:
   - name: chrome
     browser: chrome
@@ -257,3 +267,18 @@ test-suites:
     test-bundle: dart2wasm-canvaskit-ui
     run-config: chrome-full
     artifact-deps: [ canvaskit ]
+
+  - name: chrome-fallbacks
+    test-bundle: fallbacks
+    run-config: chrome
+    artifact-deps: [ canvaskit, skwasm ]
+
+  - name: firefox-fallbacks
+    test-bundle: fallbacks
+    run-config: firefox
+    artifact-deps: [ canvaskit ]
+
+  - name: safari-fallbacks
+    test-bundle: fallbacks
+    run-config: safari
+    artifact-deps: [ canvaskit ]

From 77f2673c49ce4abace4a015cc1cbc8552a61613b Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Fri, 15 Dec 2023 13:01:59 -0800
Subject: [PATCH 17/33] Add some additional types and JSDoc comments.

---
 lib/web_ui/flutter_js/sources.gni             |  2 ++
 .../flutter_js/src/entrypoint_loader.js       | 22 ++++++++++++
 lib/web_ui/flutter_js/src/loader.js           |  8 +++++
 .../flutter_js/src/service_worker_loader.js   |  4 +--
 lib/web_ui/flutter_js/src/types.d.ts          | 36 +++++++++++++++++--
 5 files changed, 67 insertions(+), 5 deletions(-)

diff --git a/lib/web_ui/flutter_js/sources.gni b/lib/web_ui/flutter_js/sources.gni
index 1bd0b3b96b966..9e829fa850e75 100644
--- a/lib/web_ui/flutter_js/sources.gni
+++ b/lib/web_ui/flutter_js/sources.gni
@@ -11,4 +11,6 @@ flutter_js_source_list = [
   "src/service_worker_loader.js",
   "src/skwasm_loader.js",
   "src/trusted_types.js",
+
+  "src/types.d.ts",
 ]
diff --git a/lib/web_ui/flutter_js/src/entrypoint_loader.js b/lib/web_ui/flutter_js/src/entrypoint_loader.js
index e8ab0dc7c17a7..b38d2306c9bc5 100644
--- a/lib/web_ui/flutter_js/src/entrypoint_loader.js
+++ b/lib/web_ui/flutter_js/src/entrypoint_loader.js
@@ -38,6 +38,7 @@ export class FlutterEntrypointLoader {
     this._ttPolicy = policy;
   }
   /**
+   * @deprecated
    * Loads flutter main entrypoint, specified by `entrypointUrl`, and calls a
    * user-specified `onEntrypointLoaded` callback with an EngineInitializer
    * object when it's done.
@@ -53,6 +54,21 @@ export class FlutterEntrypointLoader {
     return this._loadJSEntrypoint(entrypointUrl, onEntrypointLoaded, nonce);
   }
 
+  /**
+   * Loads the entry point for a flutter application.
+   * @param {import("./types").ApplicationBuild} build
+   *   Information about the specific build that is to be loaded
+   * @param {*} deps
+   *   External dependencies that may be needed to load the app.
+   * @param {import("./types").FlutterConfiguration} config
+   *   The application configuration. If no callback is specified, this will be
+   *   passed along to engine when initializing it.
+   * @param {import("./types").OnEntrypointLoadedCallback?} onEntrypointLoaded
+   *   An optional callback to invoke when the entrypoint is loaded. If no
+   *   callback is supplied, the engine initializer and app runner will be
+   *   automatically invoked on load, passing along the supplied flutter
+   *   configuration.
+   */
   async load(build, deps, config, onEntrypointLoaded) {
     onEntrypointLoaded ??= (engineInitializer) => {
       engineInitializer.initializeEngine(config).then((appRunner) => appRunner.runApp())
@@ -128,6 +144,12 @@ export class FlutterEntrypointLoader {
     }
   }
 
+  /**
+   *
+   * @param {import("./types").WasmApplicationBuild} build
+   * @param {*} deps
+   * @param {import("./types").OnEntrypointLoadedCallback} onEntrypointLoaded
+   */
   async _loadWasmEntrypoint(build, deps, onEntrypointLoaded) {
     if (!this._scriptLoaded) {
       this._scriptLoaded = true;
diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
index eb54e023e304c..e5cf5d48b2f5c 100644
--- a/lib/web_ui/flutter_js/src/loader.js
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -17,6 +17,7 @@ import { loadSkwasm } from './skwasm_loader.js';
  */
 export class FlutterLoader {
   /**
+   * @deprecated Use `load` instead.
    * Initializes the Flutter web app.
    * @param {*} options
    * @returns {Promise?} a (Deprecated) Promise that will eventually resolve
@@ -46,6 +47,13 @@ export class FlutterLoader {
     return entrypointLoader.loadEntrypoint(entrypoint);
   }
 
+  /**
+   * Loads and initializes a flutter application.
+   * @param {Object} options
+   * @param {import("/.types".ServiceWorkerSettings)} options.serviceWorkerSettings
+   * @param {import("/.types".OnEntryPointLoadedCallback)} options.onEntrypointLoaded
+   * @param {import("./types".FlutterConfiguration)} arg.config
+   */
   async load({
     serviceWorkerSettings,
     onEntrypointLoaded,
diff --git a/lib/web_ui/flutter_js/src/service_worker_loader.js b/lib/web_ui/flutter_js/src/service_worker_loader.js
index d96e92a83a36d..3cb78504d3890 100644
--- a/lib/web_ui/flutter_js/src/service_worker_loader.js
+++ b/lib/web_ui/flutter_js/src/service_worker_loader.js
@@ -55,7 +55,7 @@ export class FlutterServiceWorkerLoader {
    * configured by `settings` has been loaded and activated.
    *
    * Otherwise, the promise is rejected with an error message.
-   * @param {*} settings Service worker settings
+   * @param {import("./types").ServiceWorkerSettings} settings Service worker settings
    * @returns {Promise} that resolves when the latest serviceWorker is ready.
    */
   loadServiceWorker(settings) {
@@ -102,7 +102,7 @@ export class FlutterServiceWorkerLoader {
    * awaiting to be installed/updated.
    *
    * @param {ServiceWorkerRegistration} serviceWorkerRegistration
-   * @param {String} serviceWorkerVersion
+   * @param {string} serviceWorkerVersion
    * @returns {Promise<ServiceWorker>}
    */
   async _getNewServiceWorker(serviceWorkerRegistration, serviceWorkerVersion) {
diff --git a/lib/web_ui/flutter_js/src/types.d.ts b/lib/web_ui/flutter_js/src/types.d.ts
index e5b628a717aae..ca87269bf4c31 100644
--- a/lib/web_ui/flutter_js/src/types.d.ts
+++ b/lib/web_ui/flutter_js/src/types.d.ts
@@ -18,13 +18,13 @@ interface ApplicationBuildBase {
 
 export interface JSApplicationBuild extends ApplicationBuildBase {
     compileTarget: JSCompileTarget;
-    mainJsPath: String;
+    mainJsPath: string;
 }
 
 export interface WasmApplicationBuild extends ApplicationBuildBase {
     compileTarget: WasmCompileTarget;
-    mainWasmPath: String;
-    jsSupportRuntimePath: String;
+    mainWasmPath: string;
+    jsSupportRuntimePath: string;
 }
 
 export type ApplicationBuild = JSApplicationBuild | WasmApplicationBuild;
@@ -40,3 +40,33 @@ export interface BrowserEnvironment {
     supportsWasmGC: boolean;
     crossOriginIsolated: boolean;
 }
+
+type CanvasKitVariant =
+  "auto" |
+  "full" |
+  "chromium";
+
+export interface FlutterConfiguration {
+    assetBase: string?;
+    canvasKitBaseUrl: string?;
+    canvasKitVariant: CanvasKitVariant?;
+    renderer: WebRenderer?;
+    hostElement: HtmlElement?;
+}
+
+export interface ServiceWorkerSettings {
+    serviceWorkerVersion: string;
+    serviceWorkerUrl: string?;
+    timeoutMillis: number?;
+}
+
+export interface AppRunner {
+    runApp: () => void;
+}
+
+export interface EngineInitializer {
+    initializeEngine: () => Promise<AppRunner>;
+}
+
+export type OnEntrypointLoadedCallback =
+  (initializer: EngineInitializer) => void;

From d603f4074efcb498ec5a87c96c5f30d92532bbaa Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Fri, 15 Dec 2023 14:51:35 -0800
Subject: [PATCH 18/33] Add nonce support.

---
 .../flutter_js/src/entrypoint_loader.js       |  6 +++--
 lib/web_ui/flutter_js/src/loader.js           | 27 +++++++++++++------
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/lib/web_ui/flutter_js/src/entrypoint_loader.js b/lib/web_ui/flutter_js/src/entrypoint_loader.js
index b38d2306c9bc5..a4084470e61e7 100644
--- a/lib/web_ui/flutter_js/src/entrypoint_loader.js
+++ b/lib/web_ui/flutter_js/src/entrypoint_loader.js
@@ -63,13 +63,15 @@ export class FlutterEntrypointLoader {
    * @param {import("./types").FlutterConfiguration} config
    *   The application configuration. If no callback is specified, this will be
    *   passed along to engine when initializing it.
+   * @param {string} nonce
+   *   A nonce to apply to the main application script tag, if necessary.
    * @param {import("./types").OnEntrypointLoadedCallback?} onEntrypointLoaded
    *   An optional callback to invoke when the entrypoint is loaded. If no
    *   callback is supplied, the engine initializer and app runner will be
    *   automatically invoked on load, passing along the supplied flutter
    *   configuration.
    */
-  async load(build, deps, config, onEntrypointLoaded) {
+  async load(build, deps, config, nonce, onEntrypointLoaded) {
     onEntrypointLoaded ??= (engineInitializer) => {
       engineInitializer.initializeEngine(config).then((appRunner) => appRunner.runApp())
     };
@@ -78,7 +80,7 @@ export class FlutterEntrypointLoader {
     } else {
       const mainPath = build.mainJsPath ?? "main.dart.js";
       const entrypointUrl = `${baseUri}${mainPath}`;
-      return this._loadJSEntrypoint(entrypointUrl, onEntrypointLoaded);
+      return this._loadJSEntrypoint(entrypointUrl, onEntrypointLoaded, nonce);
     }
   }
 
diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
index e5cf5d48b2f5c..01a4eb3b7d12e 100644
--- a/lib/web_ui/flutter_js/src/loader.js
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -50,13 +50,21 @@ export class FlutterLoader {
   /**
    * Loads and initializes a flutter application.
    * @param {Object} options
-   * @param {import("/.types".ServiceWorkerSettings)} options.serviceWorkerSettings
+   * @param {import("/.types".ServiceWorkerSettings?)} options.serviceWorkerSettings
+   *   Settings for the service worker to be loaded. Can pass `undefined` or
+   *   `null` to not launch a service worker at all.
    * @param {import("/.types".OnEntryPointLoadedCallback)} options.onEntrypointLoaded
+   *   An optional callback to invoke 
+   * @param {string} options.nonce
+   *   A nonce to be applied to the main JS script when loading it, which may
+   *   be required by the sites Content-Security-Policy.
+   *   For more details, see {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/script-src here}.
    * @param {import("./types".FlutterConfiguration)} arg.config
    */
   async load({
     serviceWorkerSettings,
     onEntrypointLoaded,
+    nonce,
     config,
   } = {}) {
     config ??= {};
@@ -94,12 +102,15 @@ export class FlutterLoader {
 
     const deps = {};
     deps.flutterTT = new FlutterTrustedTypesPolicy();
-    deps.serviceWorkerLoader = new FlutterServiceWorkerLoader();
-    deps.serviceWorkerLoader.setTrustedTypesPolicy(deps.flutterTT);
-    await deps.serviceWorkerLoader.loadServiceWorker(serviceWorkerSettings).catch(e => {
-      // Regardless of what happens with the injection of the SW, the show must go on
-      console.warn("Exception while loading service worker:", e);
-    });
+    if (serviceWorkerSettings) {
+      deps.serviceWorkerLoader = new FlutterServiceWorkerLoader();
+      deps.serviceWorkerLoader.setTrustedTypesPolicy(deps.flutterTT);
+      await deps.serviceWorkerLoader.loadServiceWorker(serviceWorkerSettings).catch(e => {
+        // Regardless of what happens with the injection of the SW, the show must go on
+        console.warn("Exception while loading service worker:", e);
+      });
+    }
+
     if (build.renderer == "canvaskit") {
       deps.canvasKit = loadCanvasKit(deps, config, browserEnvironment);
     } else if (build.renderer == "skwasm") {
@@ -113,6 +124,6 @@ export class FlutterLoader {
     // Install the `didCreateEngineInitializer` listener where Flutter web expects it to be.
     this.didCreateEngineInitializer =
       entrypointLoader.didCreateEngineInitializer.bind(entrypointLoader);
-    return entrypointLoader.load(build, deps, config, onEntrypointLoaded);
+    return entrypointLoader.load(build, deps, config, nonce, onEntrypointLoaded);
   }
 }

From c66b0625f50abee5a98f78be9e35a8de113d4d9a Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Mon, 18 Dec 2023 13:48:05 -0800
Subject: [PATCH 19/33] Fix service worker's reference to `baseUri`.

---
 lib/web_ui/flutter_js/sources.gni               |  1 +
 lib/web_ui/flutter_js/src/base_uri.js           | 17 +++++++++++++++++
 lib/web_ui/flutter_js/src/entrypoint_loader.js  | 14 +-------------
 .../flutter_js/src/service_worker_loader.js     |  2 ++
 4 files changed, 21 insertions(+), 13 deletions(-)
 create mode 100644 lib/web_ui/flutter_js/src/base_uri.js

diff --git a/lib/web_ui/flutter_js/sources.gni b/lib/web_ui/flutter_js/sources.gni
index 9e829fa850e75..651a2eb53ee8a 100644
--- a/lib/web_ui/flutter_js/sources.gni
+++ b/lib/web_ui/flutter_js/sources.gni
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 flutter_js_source_list = [
+  "src/base_uri.js",
   "src/browser_environment.js",
   "src/canvaskit_loader.js",
   "src/entrypoint_loader.js",
diff --git a/lib/web_ui/flutter_js/src/base_uri.js b/lib/web_ui/flutter_js/src/base_uri.js
new file mode 100644
index 0000000000000..99f3e6c38008a
--- /dev/null
+++ b/lib/web_ui/flutter_js/src/base_uri.js
@@ -0,0 +1,17 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+export const baseUri = ensureTrailingSlash(getBaseURI());
+
+function getBaseURI() {
+  const base = document.querySelector("base");
+  return (base && base.getAttribute("href")) || "";
+}
+
+function ensureTrailingSlash(uri) {
+  if (uri == "") {
+    return uri;
+  }
+  return uri.endsWith("/") ? uri : `${uri}/`;
+}
diff --git a/lib/web_ui/flutter_js/src/entrypoint_loader.js b/lib/web_ui/flutter_js/src/entrypoint_loader.js
index a4084470e61e7..eeb4180a08afd 100644
--- a/lib/web_ui/flutter_js/src/entrypoint_loader.js
+++ b/lib/web_ui/flutter_js/src/entrypoint_loader.js
@@ -2,19 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-const baseUri = ensureTrailingSlash(getBaseURI());
-
-function getBaseURI() {
-  const base = document.querySelector("base");
-  return (base && base.getAttribute("href")) || "";
-}
-
-function ensureTrailingSlash(uri) {
-  if (uri == "") {
-    return uri;
-  }
-  return uri.endsWith("/") ? uri : `${uri}/`;
-}
+import { baseUri } from "./base_uri.js";
 
 /**
  * Handles injecting the main Flutter web entrypoint (main.dart.js), and notifying
diff --git a/lib/web_ui/flutter_js/src/service_worker_loader.js b/lib/web_ui/flutter_js/src/service_worker_loader.js
index 3cb78504d3890..8f73ed82bd679 100644
--- a/lib/web_ui/flutter_js/src/service_worker_loader.js
+++ b/lib/web_ui/flutter_js/src/service_worker_loader.js
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import { baseUri } from "./base_uri.js";
+
 /**
  * Wraps `promise` in a timeout of the given `duration` in ms.
  *

From f41f51cbf52c088f397e272fdcf8952062c98f7b Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Mon, 18 Dec 2023 14:25:02 -0800
Subject: [PATCH 20/33] Fix licenses.

---
 ci/licenses_golden/licenses_flutter | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index 417377f94196a..1210dd472786e 100644
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -5787,6 +5787,7 @@ ORIGIN: ../../../flutter/lib/ui/window/pointer_data_packet_converter.cc + ../../
 ORIGIN: ../../../flutter/lib/ui/window/pointer_data_packet_converter.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/ui/window/viewport_metrics.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/ui/window/viewport_metrics.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/base_uri.js + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/browser_environment.js + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/canvaskit_loader.js + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/entrypoint_loader.js + ../../../flutter/LICENSE
@@ -8607,6 +8608,7 @@ FILE: ../../../flutter/lib/ui/window/pointer_data_packet_converter.cc
 FILE: ../../../flutter/lib/ui/window/pointer_data_packet_converter.h
 FILE: ../../../flutter/lib/ui/window/viewport_metrics.cc
 FILE: ../../../flutter/lib/ui/window/viewport_metrics.h
+FILE: ../../../flutter/lib/web_ui/flutter_js/src/base_uri.js
 FILE: ../../../flutter/lib/web_ui/flutter_js/src/browser_environment.js
 FILE: ../../../flutter/lib/web_ui/flutter_js/src/canvaskit_loader.js
 FILE: ../../../flutter/lib/web_ui/flutter_js/src/entrypoint_loader.js

From 1a19c9c63153ecd00e1a9d1c26ed5b6484348ecf Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Mon, 18 Dec 2023 16:29:40 -0800
Subject: [PATCH 21/33] Set trusted types policy properly on service worker
 loader.

---
 lib/web_ui/flutter_js/src/loader.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
index 01a4eb3b7d12e..89693adc187d1 100644
--- a/lib/web_ui/flutter_js/src/loader.js
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -104,7 +104,7 @@ export class FlutterLoader {
     deps.flutterTT = new FlutterTrustedTypesPolicy();
     if (serviceWorkerSettings) {
       deps.serviceWorkerLoader = new FlutterServiceWorkerLoader();
-      deps.serviceWorkerLoader.setTrustedTypesPolicy(deps.flutterTT);
+      deps.serviceWorkerLoader.setTrustedTypesPolicy(deps.flutterTT.policy);
       await deps.serviceWorkerLoader.loadServiceWorker(serviceWorkerSettings).catch(e => {
         // Regardless of what happens with the injection of the SW, the show must go on
         console.warn("Exception while loading service worker:", e);

From 180608d8096393fda9d12fb609442994a69a275b Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Mon, 18 Dec 2023 17:52:44 -0800
Subject: [PATCH 22/33] Expect a trailing slash at the end of the canvaskit
 base url.

---
 lib/web_ui/flutter_js/src/canvaskit_loader.js | 4 ++--
 lib/web_ui/flutter_js/src/skwasm_loader.js    | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/web_ui/flutter_js/src/canvaskit_loader.js b/lib/web_ui/flutter_js/src/canvaskit_loader.js
index 847f3593e8a73..f6092e2ad1833 100644
--- a/lib/web_ui/flutter_js/src/canvaskit_loader.js
+++ b/lib/web_ui/flutter_js/src/canvaskit_loader.js
@@ -11,8 +11,8 @@ export const loadCanvasKit = (deps, config, browserEnvironment) => {
       throw "Chromium CanvasKit variant specifically requested, but unsupported in this browser";
     }
     const useChromiumCanvasKit = supportsChromiumCanvasKit && (config.canvasKitVariant !== "full");
-    const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}`;
-    let canvasKitUrl = useChromiumCanvasKit ? `${baseUrl}/chromium/canvaskit.js` : `${baseUrl}/canvaskit.js`;
+    const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}/`;
+    let canvasKitUrl = useChromiumCanvasKit ? `${baseUrl}/chromium/canvaskit.js` : `${baseUrl}canvaskit.js`;
     if (deps.flutterTT.policy) {
       canvasKitUrl = deps.flutterTT.policy.createScriptURL(canvasKitUrl);
     }
diff --git a/lib/web_ui/flutter_js/src/skwasm_loader.js b/lib/web_ui/flutter_js/src/skwasm_loader.js
index 2bfb8e3f0803b..cad3678a17ec9 100644
--- a/lib/web_ui/flutter_js/src/skwasm_loader.js
+++ b/lib/web_ui/flutter_js/src/skwasm_loader.js
@@ -6,8 +6,8 @@ import { engineRevision } from "./revision.js";
 
 export const loadSkwasm = (deps, config, browserEnvironment) => {
     return new Promise((resolve, reject) => {
-      const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}`;
-      let skwasmUrl = `${baseUrl}/skwasm.js`;
+      const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}/`;
+      let skwasmUrl = `${baseUrl}skwasm.js`;
       if (deps.flutterTT.policy) {
         skwasmUrl = deps.flutterTT.policy.createScriptURL(skwasmUrl);
       }

From 1ff42177485a64aee4707b9b839a048aed23f08b Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Tue, 19 Dec 2023 09:32:26 -0800
Subject: [PATCH 23/33] Make sure skwasm works when hosted via CDN.

---
 lib/web_ui/flutter_js/src/skwasm_loader.js | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/lib/web_ui/flutter_js/src/skwasm_loader.js b/lib/web_ui/flutter_js/src/skwasm_loader.js
index cad3678a17ec9..daf23b9d82c1e 100644
--- a/lib/web_ui/flutter_js/src/skwasm_loader.js
+++ b/lib/web_ui/flutter_js/src/skwasm_loader.js
@@ -15,7 +15,22 @@ export const loadSkwasm = (deps, config, browserEnvironment) => {
       script.src = skwasmUrl;
       script.addEventListener('load', async () => {
         try {
-          const skwasmInstance = await skwasm();
+          const skwasmInstance = await skwasm({
+            locateFile: (fileName, scriptDirectory) => {
+              // When hosted via a CDN or some other url that is not the same
+              // origin as the main script of the page, we will fail to create
+              // a web worker with the .worker.js script. This workaround will
+              // make sure that the worker JS can be loaded regardless of where
+              // it is hosted.
+              const url = scriptDirectory + fileName;
+              if (url.endsWith('.worker.js')) {
+                return URL.createObjectURL(new Blob(
+                  [`importScripts('${url}');`],
+                  {'type': 'application/javascript'}));
+              }
+              return url;
+            }
+        });
           resolve(skwasmInstance);
         } catch (e) {
           reject(e);

From 1a4a0a6232fdb509c9b8fbea94842c4969b429bc Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 21 Dec 2023 09:47:02 -0800
Subject: [PATCH 24/33] Optimize loading waterfall for CanvasKit and Skwasm.

---
 lib/web_ui/flutter_js/sources.gni             |  1 +
 lib/web_ui/flutter_js/src/canvaskit_loader.js | 13 ++++++++++---
 lib/web_ui/flutter_js/src/instantiate_wasm.js | 19 +++++++++++++++++++
 lib/web_ui/flutter_js/src/skwasm_loader.js    |  3 +++
 4 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 lib/web_ui/flutter_js/src/instantiate_wasm.js

diff --git a/lib/web_ui/flutter_js/sources.gni b/lib/web_ui/flutter_js/sources.gni
index 651a2eb53ee8a..11da02b200455 100644
--- a/lib/web_ui/flutter_js/sources.gni
+++ b/lib/web_ui/flutter_js/sources.gni
@@ -8,6 +8,7 @@ flutter_js_source_list = [
   "src/canvaskit_loader.js",
   "src/entrypoint_loader.js",
   "src/flutter.js",
+  "src/instantiate_wasm.js",
   "src/loader.js",
   "src/service_worker_loader.js",
   "src/skwasm_loader.js",
diff --git a/lib/web_ui/flutter_js/src/canvaskit_loader.js b/lib/web_ui/flutter_js/src/canvaskit_loader.js
index f6092e2ad1833..0387bd85b19fa 100644
--- a/lib/web_ui/flutter_js/src/canvaskit_loader.js
+++ b/lib/web_ui/flutter_js/src/canvaskit_loader.js
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import { engineRevision } from "./revision.js";
+import { createWasmInstantiator } from "./instantiate_wasm.js";
 
 export const loadCanvasKit = (deps, config, browserEnvironment) => {
   window.flutterCanvasKitLoaded = new Promise((resolve, reject) => {
@@ -11,16 +12,22 @@ export const loadCanvasKit = (deps, config, browserEnvironment) => {
       throw "Chromium CanvasKit variant specifically requested, but unsupported in this browser";
     }
     const useChromiumCanvasKit = supportsChromiumCanvasKit && (config.canvasKitVariant !== "full");
-    const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}/`;
-    let canvasKitUrl = useChromiumCanvasKit ? `${baseUrl}/chromium/canvaskit.js` : `${baseUrl}canvaskit.js`;
+    let baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}/`;
+    if (useChromiumCanvasKit) {
+      baseUrl = `${baseUrl}/chromium/`;
+    }
+    let canvasKitUrl = `${baseUrl}canvaskit.js`;
     if (deps.flutterTT.policy) {
       canvasKitUrl = deps.flutterTT.policy.createScriptURL(canvasKitUrl);
     }
+    const wasmInstantiator = createWasmInstantiator(`${baseUrl}canvaskit.wasm`);
     const script = document.createElement("script");
     script.src = canvasKitUrl;
     script.addEventListener('load', async () => {
       try {
-        const canvasKit = await CanvasKitInit();
+        const canvasKit = await CanvasKitInit({
+          instantiateWasm: wasmInstantiator,
+        });
         window.flutterCanvasKit = canvasKit;
         resolve(canvasKit);  
       } catch (e) {
diff --git a/lib/web_ui/flutter_js/src/instantiate_wasm.js b/lib/web_ui/flutter_js/src/instantiate_wasm.js
new file mode 100644
index 0000000000000..f02a653042d97
--- /dev/null
+++ b/lib/web_ui/flutter_js/src/instantiate_wasm.js
@@ -0,0 +1,19 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This is a little helper function that helps us start the fetch and compilation
+// of an emscripten wasm module in parallel with the fetch of its script.
+export const createWasmInstantiator = (url) => {
+    console.log(`starting compile of module at ${url}`);
+    const modulePromise = WebAssembly.compileStreaming(fetch(url));
+    return (imports, successCallback) => {
+        console.log(`starting instantiation of module at ${url}`);
+        (async () => {
+            const module = await modulePromise;
+            const instance = await WebAssembly.instantiate(module, imports);
+            successCallback(instance, module);
+        })();
+        return {};
+    };
+}
\ No newline at end of file
diff --git a/lib/web_ui/flutter_js/src/skwasm_loader.js b/lib/web_ui/flutter_js/src/skwasm_loader.js
index daf23b9d82c1e..810bdcb160452 100644
--- a/lib/web_ui/flutter_js/src/skwasm_loader.js
+++ b/lib/web_ui/flutter_js/src/skwasm_loader.js
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import { engineRevision } from "./revision.js";
+import { createWasmInstantiator } from "./instantiate_wasm.js";
 
 export const loadSkwasm = (deps, config, browserEnvironment) => {
     return new Promise((resolve, reject) => {
@@ -11,11 +12,13 @@ export const loadSkwasm = (deps, config, browserEnvironment) => {
       if (deps.flutterTT.policy) {
         skwasmUrl = deps.flutterTT.policy.createScriptURL(skwasmUrl);
       }
+      const wasmInstantiator = createWasmInstantiator(`${baseUrl}skwasm.wasm`);
       const script = document.createElement("script");
       script.src = skwasmUrl;
       script.addEventListener('load', async () => {
         try {
           const skwasmInstance = await skwasm({
+            instantiateWasm: wasmInstantiator,
             locateFile: (fileName, scriptDirectory) => {
               // When hosted via a CDN or some other url that is not the same
               // origin as the main script of the page, we will fail to create

From 30349fa2e69c49bc4babe9f30d11edc4d3672e6f Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 21 Dec 2023 09:52:19 -0800
Subject: [PATCH 25/33] Fix whitespace.

---
 lib/web_ui/flutter_js/src/skwasm_loader.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/web_ui/flutter_js/src/skwasm_loader.js b/lib/web_ui/flutter_js/src/skwasm_loader.js
index 810bdcb160452..a9f6028462a7b 100644
--- a/lib/web_ui/flutter_js/src/skwasm_loader.js
+++ b/lib/web_ui/flutter_js/src/skwasm_loader.js
@@ -45,4 +45,3 @@ export const loadSkwasm = (deps, config, browserEnvironment) => {
       document.head.appendChild(script);
     });
   }
-  
\ No newline at end of file

From cec8c2c381d74480f084eed7e95c6538453b6696 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 21 Dec 2023 09:53:27 -0800
Subject: [PATCH 26/33] Remove log messages and add newline at the end of file.

---
 lib/web_ui/flutter_js/src/instantiate_wasm.js | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/lib/web_ui/flutter_js/src/instantiate_wasm.js b/lib/web_ui/flutter_js/src/instantiate_wasm.js
index f02a653042d97..dd43fe2c6509e 100644
--- a/lib/web_ui/flutter_js/src/instantiate_wasm.js
+++ b/lib/web_ui/flutter_js/src/instantiate_wasm.js
@@ -5,10 +5,8 @@
 // This is a little helper function that helps us start the fetch and compilation
 // of an emscripten wasm module in parallel with the fetch of its script.
 export const createWasmInstantiator = (url) => {
-    console.log(`starting compile of module at ${url}`);
     const modulePromise = WebAssembly.compileStreaming(fetch(url));
     return (imports, successCallback) => {
-        console.log(`starting instantiation of module at ${url}`);
         (async () => {
             const module = await modulePromise;
             const instance = await WebAssembly.instantiate(module, imports);
@@ -16,4 +14,4 @@ export const createWasmInstantiator = (url) => {
         })();
         return {};
     };
-}
\ No newline at end of file
+}

From 8df86a5437ed0503624add84ca4215faec12b518 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 21 Dec 2023 10:10:56 -0800
Subject: [PATCH 27/33] Fixed licenses golden.

---
 ci/licenses_golden/licenses_flutter | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index 1210dd472786e..2885c8dc9b71b 100644
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -5792,6 +5792,7 @@ ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/browser_environment.js + ../.
 ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/canvaskit_loader.js + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/entrypoint_loader.js + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/flutter.js + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/instantiate_wasm.js + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/loader.js + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/service_worker_loader.js + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/flutter_js/src/skwasm_loader.js + ../../../flutter/LICENSE
@@ -8613,6 +8614,7 @@ FILE: ../../../flutter/lib/web_ui/flutter_js/src/browser_environment.js
 FILE: ../../../flutter/lib/web_ui/flutter_js/src/canvaskit_loader.js
 FILE: ../../../flutter/lib/web_ui/flutter_js/src/entrypoint_loader.js
 FILE: ../../../flutter/lib/web_ui/flutter_js/src/flutter.js
+FILE: ../../../flutter/lib/web_ui/flutter_js/src/instantiate_wasm.js
 FILE: ../../../flutter/lib/web_ui/flutter_js/src/loader.js
 FILE: ../../../flutter/lib/web_ui/flutter_js/src/service_worker_loader.js
 FILE: ../../../flutter/lib/web_ui/flutter_js/src/skwasm_loader.js

From d3ebe8ef9a67b5bf1efff00a66179e87e967430e Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 21 Dec 2023 11:41:12 -0800
Subject: [PATCH 28/33] Fix some indentation and formatting on JS files.

---
 .../flutter_js/src/browser_environment.js     | 60 ++++++++--------
 lib/web_ui/flutter_js/src/instantiate_wasm.js | 18 ++---
 lib/web_ui/flutter_js/src/loader.js           |  6 +-
 lib/web_ui/flutter_js/src/skwasm_loader.js    | 70 +++++++++----------
 lib/web_ui/flutter_js/src/trusted_types.js    |  2 +-
 lib/web_ui/flutter_js/src/types.d.ts          | 50 ++++++-------
 6 files changed, 103 insertions(+), 103 deletions(-)

diff --git a/lib/web_ui/flutter_js/src/browser_environment.js b/lib/web_ui/flutter_js/src/browser_environment.js
index 185c8e05731f2..1b813cbd69ef1 100644
--- a/lib/web_ui/flutter_js/src/browser_environment.js
+++ b/lib/web_ui/flutter_js/src/browser_environment.js
@@ -6,46 +6,46 @@
  * @returns {import("./types").BrowserEnvironment}
  */
 export const detectBrowserEnvironment = () => {
-    return {
-        hasImageCodecs: hasImageCodecs(),
-        hasChromiumBreakIterators: hasChromiumBreakIterators(),
-        supportsWasmGC: supportsWasmGC(),
-        crossOriginIsolated: window.crossOriginIsolated,
-    };
+  return {
+    hasImageCodecs: hasImageCodecs(),
+    hasChromiumBreakIterators: hasChromiumBreakIterators(),
+    supportsWasmGC: supportsWasmGC(),
+    crossOriginIsolated: window.crossOriginIsolated,
+  };
 }
 
 const isBlink = () => {
-    return (navigator.vendor === 'Google Inc.') ||
-        (navigator.agent == 'Edg/');
+  return (navigator.vendor === 'Google Inc.') ||
+    (navigator.agent == 'Edg/');
 }
 
 const hasImageCodecs = () => {
-    if (typeof ImageDecoder === 'undefined') {
-        return false;
-    }
-    // TODO(yjbanov): https://github.com/flutter/flutter/issues/122761
-    // Frequently, when a browser launches an API that other browsers already
-    // support, there are subtle incompatibilities that may cause apps to crash if,
-    // we blindly adopt the new implementation. This check prevents us from picking
-    // up potentially incompatible implementations of ImagdeDecoder API. Instead,
-    // when a new browser engine launches the API, we'll evaluate it and enable it
-    // explicitly.
-    if (!isBlink()) {
-        return false;
-    }
-    return true;
+  if (typeof ImageDecoder === 'undefined') {
+    return false;
+  }
+  // TODO(yjbanov): https://github.com/flutter/flutter/issues/122761
+  // Frequently, when a browser launches an API that other browsers already
+  // support, there are subtle incompatibilities that may cause apps to crash if,
+  // we blindly adopt the new implementation. This check prevents us from picking
+  // up potentially incompatible implementations of ImagdeDecoder API. Instead,
+  // when a new browser engine launches the API, we'll evaluate it and enable it
+  // explicitly.
+  if (!isBlink()) {
+    return false;
+  }
+  return true;
 }
 
 const hasChromiumBreakIterators = () => {
-    return (typeof Intl.v8BreakIterator !== "undefined") &&
-        (typeof Intl.Segmenter !== "undefined");
+  return (typeof Intl.v8BreakIterator !== "undefined") &&
+    (typeof Intl.Segmenter !== "undefined");
 }
 
 const supportsWasmGC = () => {
-    // This attempts to instantiate a wasm module that only will validate if the
-    // final WasmGC spec is implemented in the browser.
-    //
-    // Copied from https://github.com/GoogleChromeLabs/wasm-feature-detect/blob/main/src/detectors/gc/index.js
-    const bytes = [0, 97, 115, 109, 1, 0, 0, 0, 1, 5, 1, 95, 1, 120, 0];
-    return WebAssembly.validate(new Uint8Array(bytes));
+  // This attempts to instantiate a wasm module that only will validate if the
+  // final WasmGC spec is implemented in the browser.
+  //
+  // Copied from https://github.com/GoogleChromeLabs/wasm-feature-detect/blob/main/src/detectors/gc/index.js
+  const bytes = [0, 97, 115, 109, 1, 0, 0, 0, 1, 5, 1, 95, 1, 120, 0];
+  return WebAssembly.validate(new Uint8Array(bytes));
 }
diff --git a/lib/web_ui/flutter_js/src/instantiate_wasm.js b/lib/web_ui/flutter_js/src/instantiate_wasm.js
index dd43fe2c6509e..29827f6563131 100644
--- a/lib/web_ui/flutter_js/src/instantiate_wasm.js
+++ b/lib/web_ui/flutter_js/src/instantiate_wasm.js
@@ -5,13 +5,13 @@
 // This is a little helper function that helps us start the fetch and compilation
 // of an emscripten wasm module in parallel with the fetch of its script.
 export const createWasmInstantiator = (url) => {
-    const modulePromise = WebAssembly.compileStreaming(fetch(url));
-    return (imports, successCallback) => {
-        (async () => {
-            const module = await modulePromise;
-            const instance = await WebAssembly.instantiate(module, imports);
-            successCallback(instance, module);
-        })();
-        return {};
-    };
+  const modulePromise = WebAssembly.compileStreaming(fetch(url));
+  return (imports, successCallback) => {
+    (async () => {
+      const module = await modulePromise;
+      const instance = await WebAssembly.instantiate(module, imports);
+      successCallback(instance, module);
+    })();
+    return {};
+  };
 }
diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
index 89693adc187d1..bcf71c9870ab3 100644
--- a/lib/web_ui/flutter_js/src/loader.js
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -77,9 +77,9 @@ export class FlutterLoader {
     const rendererIsCompatible = (renderer) => {
       switch (renderer) {
         case "skwasm":
-          return browserEnvironment.crossOriginIsolated 
-            && browserEnvironment.hasChromiumBreakIterators 
-            && browserEnvironment.hasImageCodecs 
+          return browserEnvironment.crossOriginIsolated
+            && browserEnvironment.hasChromiumBreakIterators
+            && browserEnvironment.hasImageCodecs
             && browserEnvironment.supportsWasmGC;
         default:
           return true;
diff --git a/lib/web_ui/flutter_js/src/skwasm_loader.js b/lib/web_ui/flutter_js/src/skwasm_loader.js
index a9f6028462a7b..5c0388b39e695 100644
--- a/lib/web_ui/flutter_js/src/skwasm_loader.js
+++ b/lib/web_ui/flutter_js/src/skwasm_loader.js
@@ -6,42 +6,42 @@ import { engineRevision } from "./revision.js";
 import { createWasmInstantiator } from "./instantiate_wasm.js";
 
 export const loadSkwasm = (deps, config, browserEnvironment) => {
-    return new Promise((resolve, reject) => {
-      const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}/`;
-      let skwasmUrl = `${baseUrl}skwasm.js`;
-      if (deps.flutterTT.policy) {
-        skwasmUrl = deps.flutterTT.policy.createScriptURL(skwasmUrl);
-      }
-      const wasmInstantiator = createWasmInstantiator(`${baseUrl}skwasm.wasm`);
-      const script = document.createElement("script");
-      script.src = skwasmUrl;
-      script.addEventListener('load', async () => {
-        try {
-          const skwasmInstance = await skwasm({
-            instantiateWasm: wasmInstantiator,
-            locateFile: (fileName, scriptDirectory) => {
-              // When hosted via a CDN or some other url that is not the same
-              // origin as the main script of the page, we will fail to create
-              // a web worker with the .worker.js script. This workaround will
-              // make sure that the worker JS can be loaded regardless of where
-              // it is hosted.
-              const url = scriptDirectory + fileName;
-              if (url.endsWith('.worker.js')) {
-                return URL.createObjectURL(new Blob(
-                  [`importScripts('${url}');`],
-                  {'type': 'application/javascript'}));
-              }
-              return url;
+  return new Promise((resolve, reject) => {
+    const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}/`;
+    let skwasmUrl = `${baseUrl}skwasm.js`;
+    if (deps.flutterTT.policy) {
+      skwasmUrl = deps.flutterTT.policy.createScriptURL(skwasmUrl);
+    }
+    const wasmInstantiator = createWasmInstantiator(`${baseUrl}skwasm.wasm`);
+    const script = document.createElement("script");
+    script.src = skwasmUrl;
+    script.addEventListener('load', async () => {
+      try {
+        const skwasmInstance = await skwasm({
+          instantiateWasm: wasmInstantiator,
+          locateFile: (fileName, scriptDirectory) => {
+            // When hosted via a CDN or some other url that is not the same
+            // origin as the main script of the page, we will fail to create
+            // a web worker with the .worker.js script. This workaround will
+            // make sure that the worker JS can be loaded regardless of where
+            // it is hosted.
+            const url = scriptDirectory + fileName;
+            if (url.endsWith('.worker.js')) {
+              return URL.createObjectURL(new Blob(
+                [`importScripts('${url}');`],
+                { 'type': 'application/javascript' }));
             }
+            return url;
+          }
         });
-          resolve(skwasmInstance);
-        } catch (e) {
-          reject(e);
-        }
-      });
-      script.addEventListener('error', (e) => {
+        resolve(skwasmInstance);
+      } catch (e) {
         reject(e);
-      });
-      document.head.appendChild(script);
+      }
+    });
+    script.addEventListener('error', (e) => {
+      reject(e);
     });
-  }
+    document.head.appendChild(script);
+  });
+}
diff --git a/lib/web_ui/flutter_js/src/trusted_types.js b/lib/web_ui/flutter_js/src/trusted_types.js
index 527f06f7b59bc..76db604dbaf17 100644
--- a/lib/web_ui/flutter_js/src/trusted_types.js
+++ b/lib/web_ui/flutter_js/src/trusted_types.js
@@ -19,7 +19,7 @@ export class FlutterTrustedTypesPolicy {
     ];
     if (window.trustedTypes) {
       this.policy = trustedTypes.createPolicy(policyName, {
-        createScriptURL: function(url) {
+        createScriptURL: function (url) {
           const parsed = new URL(url, window.location);
           const file = parsed.pathname.split("/").pop();
           const matches = patterns.some((pattern) => pattern.test(file));
diff --git a/lib/web_ui/flutter_js/src/types.d.ts b/lib/web_ui/flutter_js/src/types.d.ts
index ca87269bf4c31..c828838b19e26 100644
--- a/lib/web_ui/flutter_js/src/types.d.ts
+++ b/lib/web_ui/flutter_js/src/types.d.ts
@@ -8,37 +8,37 @@ type WasmCompileTarget = "dart2wasm";
 export type CompileTarget = JSCompileTarget | WasmCompileTarget;
 
 export type WebRenderer =
-    "html" |
-    "canvaskit" |
-    "skwasm";
+  "html" |
+  "canvaskit" |
+  "skwasm";
 
 interface ApplicationBuildBase {
-    renderer: WebRenderer;
+  renderer: WebRenderer;
 }
 
 export interface JSApplicationBuild extends ApplicationBuildBase {
-    compileTarget: JSCompileTarget;
-    mainJsPath: string;
+  compileTarget: JSCompileTarget;
+  mainJsPath: string;
 }
 
 export interface WasmApplicationBuild extends ApplicationBuildBase {
-    compileTarget: WasmCompileTarget;
-    mainWasmPath: string;
-    jsSupportRuntimePath: string;
+  compileTarget: WasmCompileTarget;
+  mainWasmPath: string;
+  jsSupportRuntimePath: string;
 }
 
 export type ApplicationBuild = JSApplicationBuild | WasmApplicationBuild;
 
 export interface BuildConfig {
-    serviceWorkerVersion: string;
-    builds: ApplicationBuild[];
+  serviceWorkerVersion: string;
+  builds: ApplicationBuild[];
 }
 
 export interface BrowserEnvironment {
-    hasImageCodecs: boolean;
-    hasChromiumBreakIterators: boolean; 
-    supportsWasmGC: boolean;
-    crossOriginIsolated: boolean;
+  hasImageCodecs: boolean;
+  hasChromiumBreakIterators: boolean;
+  supportsWasmGC: boolean;
+  crossOriginIsolated: boolean;
 }
 
 type CanvasKitVariant =
@@ -47,25 +47,25 @@ type CanvasKitVariant =
   "chromium";
 
 export interface FlutterConfiguration {
-    assetBase: string?;
-    canvasKitBaseUrl: string?;
-    canvasKitVariant: CanvasKitVariant?;
-    renderer: WebRenderer?;
-    hostElement: HtmlElement?;
+  assetBase: string?;
+  canvasKitBaseUrl: string?;
+  canvasKitVariant: CanvasKitVariant?;
+  renderer: WebRenderer?;
+  hostElement: HtmlElement?;
 }
 
 export interface ServiceWorkerSettings {
-    serviceWorkerVersion: string;
-    serviceWorkerUrl: string?;
-    timeoutMillis: number?;
+  serviceWorkerVersion: string;
+  serviceWorkerUrl: string?;
+  timeoutMillis: number?;
 }
 
 export interface AppRunner {
-    runApp: () => void;
+  runApp: () => void;
 }
 
 export interface EngineInitializer {
-    initializeEngine: () => Promise<AppRunner>;
+  initializeEngine: () => Promise<AppRunner>;
 }
 
 export type OnEntrypointLoadedCallback =

From b077685aaea4c80413eeb55e6d0106d7ec15873d Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 21 Dec 2023 11:43:22 -0800
Subject: [PATCH 29/33] Addressed another of Yegor's comments.

---
 lib/web_ui/flutter_js/src/browser_environment.js | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/lib/web_ui/flutter_js/src/browser_environment.js b/lib/web_ui/flutter_js/src/browser_environment.js
index 1b813cbd69ef1..4e0bea00393ac 100644
--- a/lib/web_ui/flutter_js/src/browser_environment.js
+++ b/lib/web_ui/flutter_js/src/browser_environment.js
@@ -30,10 +30,7 @@ const hasImageCodecs = () => {
   // up potentially incompatible implementations of ImagdeDecoder API. Instead,
   // when a new browser engine launches the API, we'll evaluate it and enable it
   // explicitly.
-  if (!isBlink()) {
-    return false;
-  }
-  return true;
+  return isBlink();
 }
 
 const hasChromiumBreakIterators = () => {

From 7d45ef2b1b2fac58fc7221c2d7d92b1260af12d9 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Tue, 2 Jan 2024 11:26:13 -0800
Subject: [PATCH 30/33] Addressed some PR comments.

---
 lib/web_ui/flutter_js/BUILD.gn                | 13 -----------
 lib/web_ui/flutter_js/src/base_uri.js         |  2 +-
 .../flutter_js/src/browser_environment.js     | 22 +++++++++----------
 lib/web_ui/flutter_js/src/canvaskit_loader.js | 14 +++++++-----
 .../flutter_js/src/entrypoint_loader.js       |  4 ++--
 lib/web_ui/flutter_js/src/loader.js           | 15 +++++++------
 .../flutter_js/src/service_worker_loader.js   |  6 ++---
 lib/web_ui/flutter_js/src/skwasm_loader.js    | 10 ++++-----
 lib/web_ui/flutter_js/src/types.d.ts          |  1 +
 9 files changed, 39 insertions(+), 48 deletions(-)

diff --git a/lib/web_ui/flutter_js/BUILD.gn b/lib/web_ui/flutter_js/BUILD.gn
index 4b84d594643bf..5b6d1d31e5c19 100644
--- a/lib/web_ui/flutter_js/BUILD.gn
+++ b/lib/web_ui/flutter_js/BUILD.gn
@@ -9,7 +9,6 @@ import("sources.gni")
 group("flutter_js") {
   public_deps = [
     ":flutter_js_bundle",
-    ":flutter_js_engine_version",
     ":flutter_js_sources",
   ]
 }
@@ -20,17 +19,6 @@ copy("flutter_js_sources") {
       [ "$root_out_dir/flutter_web_sdk/flutter_js/{{source_target_relative}}" ]
 }
 
-generated_file("flutter_js_engine_version") {
-  outputs = [ "$root_out_dir/flutter_web_sdk/flutter_js/src/revision.js" ]
-  contents = [
-    "// Copyright 2013 The Flutter Authors. All rights reserved.",
-    "// Use of this source code is governed by a BSD-style license that can be",
-    "// found in the LICENSE file.",
-    "",
-    "export const engineRevision = \"$engine_version\";",
-  ]
-}
-
 esbuild("flutter_js_bundle") {
   entry_point = "$root_out_dir/flutter_web_sdk/flutter_js/src/flutter.js"
   output_bundle = "$root_out_dir/flutter_web_sdk/flutter_js"
@@ -40,7 +28,6 @@ esbuild("flutter_js_bundle") {
   sourcemap = true
 
   public_deps = [
-    ":flutter_js_engine_version",
     ":flutter_js_sources",
   ]
 }
diff --git a/lib/web_ui/flutter_js/src/base_uri.js b/lib/web_ui/flutter_js/src/base_uri.js
index 99f3e6c38008a..bfca8d341bde7 100644
--- a/lib/web_ui/flutter_js/src/base_uri.js
+++ b/lib/web_ui/flutter_js/src/base_uri.js
@@ -10,7 +10,7 @@ function getBaseURI() {
 }
 
 function ensureTrailingSlash(uri) {
-  if (uri == "") {
+  if (uri === "") {
     return uri;
   }
   return uri.endsWith("/") ? uri : `${uri}/`;
diff --git a/lib/web_ui/flutter_js/src/browser_environment.js b/lib/web_ui/flutter_js/src/browser_environment.js
index 4e0bea00393ac..41ab76ea2a3a5 100644
--- a/lib/web_ui/flutter_js/src/browser_environment.js
+++ b/lib/web_ui/flutter_js/src/browser_environment.js
@@ -2,18 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-/**
- * @returns {import("./types").BrowserEnvironment}
- */
-export const detectBrowserEnvironment = () => {
-  return {
-    hasImageCodecs: hasImageCodecs(),
-    hasChromiumBreakIterators: hasChromiumBreakIterators(),
-    supportsWasmGC: supportsWasmGC(),
-    crossOriginIsolated: window.crossOriginIsolated,
-  };
-}
-
 const isBlink = () => {
   return (navigator.vendor === 'Google Inc.') ||
     (navigator.agent == 'Edg/');
@@ -46,3 +34,13 @@ const supportsWasmGC = () => {
   const bytes = [0, 97, 115, 109, 1, 0, 0, 0, 1, 5, 1, 95, 1, 120, 0];
   return WebAssembly.validate(new Uint8Array(bytes));
 }
+
+/**
+ * @returns {import("./types").BrowserEnvironment}
+ */
+export const browserEnvironment = {
+  hasImageCodecs: hasImageCodecs(),
+  hasChromiumBreakIterators: hasChromiumBreakIterators(),
+  supportsWasmGC: supportsWasmGC(),
+  crossOriginIsolated: window.crossOriginIsolated,
+};
diff --git a/lib/web_ui/flutter_js/src/canvaskit_loader.js b/lib/web_ui/flutter_js/src/canvaskit_loader.js
index 0387bd85b19fa..cf88c3c7ea53f 100644
--- a/lib/web_ui/flutter_js/src/canvaskit_loader.js
+++ b/lib/web_ui/flutter_js/src/canvaskit_loader.js
@@ -2,10 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import { engineRevision } from "./revision.js";
 import { createWasmInstantiator } from "./instantiate_wasm.js";
 
-export const loadCanvasKit = (deps, config, browserEnvironment) => {
+export const loadCanvasKit = (deps, config, browserEnvironment, engineRevision) => {
+  if (window.flutterCanvasKit) {
+    // The user has set this global variable ahead of time, so we just return that.
+    return Promise.resolve(window.flutterCanvasKit);
+  }
   window.flutterCanvasKitLoaded = new Promise((resolve, reject) => {
     const supportsChromiumCanvasKit = browserEnvironment.hasChromiumBreakIterators && browserEnvironment.hasImageCodecs;
     if (!supportsChromiumCanvasKit && config.canvasKitVariant == "chromium") {
@@ -23,6 +26,9 @@ export const loadCanvasKit = (deps, config, browserEnvironment) => {
     const wasmInstantiator = createWasmInstantiator(`${baseUrl}canvaskit.wasm`);
     const script = document.createElement("script");
     script.src = canvasKitUrl;
+    if (config.nonce) {
+      script.nonce = config.nonce;
+    }
     script.addEventListener('load', async () => {
       try {
         const canvasKit = await CanvasKitInit({
@@ -34,9 +40,7 @@ export const loadCanvasKit = (deps, config, browserEnvironment) => {
         reject(e);
       }
     });
-    script.addEventListener('error', (e) => {
-      reject(e);
-    });
+    script.addEventListener('error', reject);
     document.head.appendChild(script);
   });
   return window.flutterCanvasKitLoaded;
diff --git a/lib/web_ui/flutter_js/src/entrypoint_loader.js b/lib/web_ui/flutter_js/src/entrypoint_loader.js
index eeb4180a08afd..db8b33159dc48 100644
--- a/lib/web_ui/flutter_js/src/entrypoint_loader.js
+++ b/lib/web_ui/flutter_js/src/entrypoint_loader.js
@@ -63,7 +63,7 @@ export class FlutterEntrypointLoader {
     onEntrypointLoaded ??= (engineInitializer) => {
       engineInitializer.initializeEngine(config).then((appRunner) => appRunner.runApp())
     };
-    if (build.compileTarget == "dart2wasm") {
+    if (build.compileTarget === "dart2wasm") {
       return this._loadWasmEntrypoint(build, deps, onEntrypointLoaded);
     } else {
       const mainPath = build.mainJsPath ?? "main.dart.js";
@@ -156,7 +156,7 @@ export class FlutterEntrypointLoader {
       const jsSupportRuntime = await import(jsSupportRuntimeUri);
 
       let imports;
-      if (build.renderer == "skwasm") {
+      if (build.renderer === "skwasm") {
         imports = (async () => {
           const skwasmInstance = await deps.skwasm;
           window._flutter_skwasmInstance = skwasmInstance;
diff --git a/lib/web_ui/flutter_js/src/loader.js b/lib/web_ui/flutter_js/src/loader.js
index bcf71c9870ab3..3d5fb4e8ddbef 100644
--- a/lib/web_ui/flutter_js/src/loader.js
+++ b/lib/web_ui/flutter_js/src/loader.js
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import { detectBrowserEnvironment } from './browser_environment.js';
+import { browserEnvironment } from './browser_environment.js';
 import { FlutterEntrypointLoader } from './entrypoint_loader.js';
 import { FlutterServiceWorkerLoader } from './service_worker_loader.js';
 import { FlutterTrustedTypesPolicy } from './trusted_types.js';
@@ -68,7 +68,8 @@ export class FlutterLoader {
     config,
   } = {}) {
     config ??= {};
-    const browserEnvironment = detectBrowserEnvironment();
+
+    /** @type {import("./types").BuildConfig} */
     const buildConfig = _flutter.buildConfig;
     if (!buildConfig) {
       throw "FlutterLoader.load requires _flutter.buildConfig to be set";
@@ -87,7 +88,7 @@ export class FlutterLoader {
     }
 
     const buildIsCompatible = (build) => {
-      if (build.compileTarget == "dart2wasm" && !browserEnvironment.supportsWasmGC) {
+      if (build.compileTarget === "dart2wasm" && !browserEnvironment.supportsWasmGC) {
         return false;
       }
       if (config.renderer && config.renderer != build.renderer) {
@@ -111,10 +112,10 @@ export class FlutterLoader {
       });
     }
 
-    if (build.renderer == "canvaskit") {
-      deps.canvasKit = loadCanvasKit(deps, config, browserEnvironment);
-    } else if (build.renderer == "skwasm") {
-      deps.skwasm = loadSkwasm(deps, config, browserEnvironment);
+    if (build.renderer === "canvaskit") {
+      deps.canvasKit = loadCanvasKit(deps, config, browserEnvironment, buildConfig.engineRevision);
+    } else if (build.renderer === "skwasm") {
+      deps.skwasm = loadSkwasm(deps, config, browserEnvironment, buildConfig.engineRevision);
     }
 
     // The FlutterEntrypointLoader instance could be injected as a dependency
diff --git a/lib/web_ui/flutter_js/src/service_worker_loader.js b/lib/web_ui/flutter_js/src/service_worker_loader.js
index 8f73ed82bd679..7c4ff3e6c39bd 100644
--- a/lib/web_ui/flutter_js/src/service_worker_loader.js
+++ b/lib/web_ui/flutter_js/src/service_worker_loader.js
@@ -61,7 +61,7 @@ export class FlutterServiceWorkerLoader {
    * @returns {Promise} that resolves when the latest serviceWorker is ready.
    */
   loadServiceWorker(settings) {
-    if (settings == null) {
+    if (!settings) {
       // In the future, settings = null -> uninstall service worker?
       console.debug("Null serviceWorker configuration. Skipping.");
       return Promise.resolve();
@@ -132,7 +132,7 @@ export class FlutterServiceWorkerLoader {
    * @returns {Promise<void>}
    */
   async _waitForServiceWorkerActivation(serviceWorker) {
-    if (!serviceWorker || serviceWorker.state == "activated") {
+    if (!serviceWorker || serviceWorker.state === "activated") {
       if (!serviceWorker) {
         throw new Error("Cannot activate a null service worker!");
       } else {
@@ -142,7 +142,7 @@ export class FlutterServiceWorkerLoader {
     }
     return new Promise((resolve, _) => {
       serviceWorker.addEventListener("statechange", () => {
-        if (serviceWorker.state == "activated") {
+        if (serviceWorker.state === "activated") {
           console.debug("Activated new service worker.");
           resolve();
         }
diff --git a/lib/web_ui/flutter_js/src/skwasm_loader.js b/lib/web_ui/flutter_js/src/skwasm_loader.js
index 5c0388b39e695..86e1b529784d3 100644
--- a/lib/web_ui/flutter_js/src/skwasm_loader.js
+++ b/lib/web_ui/flutter_js/src/skwasm_loader.js
@@ -2,10 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import { engineRevision } from "./revision.js";
 import { createWasmInstantiator } from "./instantiate_wasm.js";
 
-export const loadSkwasm = (deps, config, browserEnvironment) => {
+export const loadSkwasm = (deps, config, browserEnvironment, engineRevision) => {
   return new Promise((resolve, reject) => {
     const baseUrl = config.canvasKitBaseUrl ?? `https://www.gstatic.com/flutter-canvaskit/${engineRevision}/`;
     let skwasmUrl = `${baseUrl}skwasm.js`;
@@ -15,6 +14,9 @@ export const loadSkwasm = (deps, config, browserEnvironment) => {
     const wasmInstantiator = createWasmInstantiator(`${baseUrl}skwasm.wasm`);
     const script = document.createElement("script");
     script.src = skwasmUrl;
+    if (config.nonce) {
+      script.nonce = config.nonce;
+    }
     script.addEventListener('load', async () => {
       try {
         const skwasmInstance = await skwasm({
@@ -39,9 +41,7 @@ export const loadSkwasm = (deps, config, browserEnvironment) => {
         reject(e);
       }
     });
-    script.addEventListener('error', (e) => {
-      reject(e);
-    });
+    script.addEventListener('error', reject);
     document.head.appendChild(script);
   });
 }
diff --git a/lib/web_ui/flutter_js/src/types.d.ts b/lib/web_ui/flutter_js/src/types.d.ts
index c828838b19e26..9cd1f7a769539 100644
--- a/lib/web_ui/flutter_js/src/types.d.ts
+++ b/lib/web_ui/flutter_js/src/types.d.ts
@@ -31,6 +31,7 @@ export type ApplicationBuild = JSApplicationBuild | WasmApplicationBuild;
 
 export interface BuildConfig {
   serviceWorkerVersion: string;
+  engineRevision: string;
   builds: ApplicationBuild[];
 }
 

From cc79b91674a49968763c867a758877d4ef33bfec Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Tue, 2 Jan 2024 11:52:14 -0800
Subject: [PATCH 31/33] Fix formatting issue.

---
 lib/web_ui/flutter_js/BUILD.gn | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/lib/web_ui/flutter_js/BUILD.gn b/lib/web_ui/flutter_js/BUILD.gn
index 5b6d1d31e5c19..255cd2c513fe3 100644
--- a/lib/web_ui/flutter_js/BUILD.gn
+++ b/lib/web_ui/flutter_js/BUILD.gn
@@ -27,7 +27,5 @@ esbuild("flutter_js_bundle") {
   minify = true
   sourcemap = true
 
-  public_deps = [
-    ":flutter_js_sources",
-  ]
+  public_deps = [ ":flutter_js_sources" ]
 }

From a8954bea032a838fe106a0b2f14abcb99bc3f0b4 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Tue, 2 Jan 2024 12:15:00 -0800
Subject: [PATCH 32/33] Fix analysis error.

---
 lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart b/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart
index a6c074d4face7..39608d26cc652 100644
--- a/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart
+++ b/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart
@@ -44,7 +44,7 @@ external set windowFlutterCanvasKit(CanvasKit? value);
 external CanvasKit? get windowFlutterCanvasKit;
 
 @JS('window.flutterCanvasKitLoaded')
-external JSPromise? get windowFlutterCanvasKitLoaded;
+external JSPromise<JSAny>? get windowFlutterCanvasKitLoaded;
 
 @JS()
 @anonymous

From 63ead1ac86f52f5dae81d3ec926da31ceb736646 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 4 Jan 2024 10:48:31 -0800
Subject: [PATCH 33/33] More JS equality stuff.

---
 lib/web_ui/flutter_js/src/browser_environment.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/web_ui/flutter_js/src/browser_environment.js b/lib/web_ui/flutter_js/src/browser_environment.js
index 41ab76ea2a3a5..64baabc024270 100644
--- a/lib/web_ui/flutter_js/src/browser_environment.js
+++ b/lib/web_ui/flutter_js/src/browser_environment.js
@@ -4,7 +4,7 @@
 
 const isBlink = () => {
   return (navigator.vendor === 'Google Inc.') ||
-    (navigator.agent == 'Edg/');
+    (navigator.agent === 'Edg/');
 }
 
 const hasImageCodecs = () => {