isolate: fix how we get the current script now that frog automatically wraps the

lib/isolate/frog/isolateimpl.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Concepts used here:
  *
  * "manager" - A manager contains one or more isolates, schedules their
  * execution, and performs other plumbing on their behalf.  The isolate
  * present at the creation of the manager is designated as its "root isolate".
@@ skipping 107 matching lines @@
     topEventLoop = new _EventLoop();
     isolates = new Map<int, _IsolateContext>();
     managers = new Map<int, _ManagerStub>();
     if (isWorker) {  // "if we are not the main manager ourself" is the intent.
       mainManager = new _MainManagerStub();
       _nativeInitWorkerMessageHandler();
     }
   }
 
   void _nativeDetectEnvironment() native @"""
-    this.isWorker = typeof ($globalThis['importScripts']) != 'undefined';
+    this.isWorker = $isWorker;
+    this.supportsWorkers = $supportsWorkers;
     this.fromCommandLine = typeof(window) == 'undefined';
-    this.supportsWorkers = this.isWorker ||
-        ((typeof $globalThis['Worker']) != 'undefined');
   """;
 
   void _nativeInitWorkerMessageHandler() native @"""
     $globalThis.onmessage = function (e) {
       _IsolateNatives._processWorkerMessage(this.mainManager, e);
     }
   """ {
     _IsolateNatives._processWorkerMessage(null, null);
   }
 
@@ skipping 237 matching lines @@
           'replyPort': _serializeMessage(replyPort)}));
     } else {
       _spawnWorker(factoryName, _serializeMessage(replyPort));
     }
   }
 
   /**
    * The src url for the script tag that loaded this code. Used to create
    * JavaScript workers.
    */
-  static String get _thisScript() {
-    if (_thisScriptCache == null) {
-      _thisScriptCache = _computeThisScript();
-    }
-    return _thisScriptCache;
-  }
-
-  static String _thisScriptCache;
-
-  // TODO(sigmund): fix - this code should be run synchronously when loading the
-  // script. Running lazily on DOMContentLoaded will yield incorrect results.
-  static String _computeThisScript() native @"""
-    if (!$globalState.supportsWorkers || $globalState.isWorker) return (void 0);
-
-    // TODO(5334778): Find a cross-platform non-brittle way of getting the
-    // currently running script.
-    var scripts = document.getElementsByTagName('script');
-    // The scripts variable only contains the scripts that have already been
-    // executed. The last one is the currently running script.
-    var script = scripts[scripts.length - 1];
-    var src = script && script.src;
-    if (!src) {
-      // TODO()
-      src = "FIXME:5407062" + "_" + Math.random().toString();
-      if (script) script.src = src;
-    }
-    return src;
-  """;
+  static String get _thisScript() native @"return $thisScriptUrl";
 
   /** Starts a new worker with the given URL. */
   static _WorkerStub _newWorker(url) native "return new Worker(url);";
 
   /**
    * Spawns an isolate in a worker. [factoryName] is the Javascript constructor
    * name for the isolate entry point class.
    */
   static void _spawnWorker(factoryName, serializedReplyPort) {
     final worker = _newWorker(_thisScript);
@@ skipping 248 matching lines @@
       'command': 'start2',
       'id': workerId,
       // Note: we serialize replyPort twice because the child worker needs to
       // first deserialize the worker id, before it can correctly deserialize
       // the port (port deserialization is sensitive to what is the current
       // workerId).
       'replyTo': _serializeMessage(replyPort),
       'functionName': functionName }));
   }
 }