Remove _WorkerStub hack to make benefit closing an isolate.

dart/sdk/lib/_internal/compiler/implementation/lib/isolate_helper.dart

Index: dart/sdk/lib/_internal/compiler/implementation/lib/isolate_helper.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/lib/isolate_helper.dart b/dart/sdk/lib/_internal/compiler/implementation/lib/isolate_helper.dart
index ebbb9fd02a566663cd58f7f630b8ba1387d653ff..59ea2eb8640b7f4b638a19162ba5c1c860d86c6f 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/lib/isolate_helper.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/lib/isolate_helper.dart
@@ -107,7 +107,9 @@ void startRootIsolate(entry) {
  * [_ManagerStub] - A handle held within one manager that allows interaction
  * with another manager.  A target manager may be addressed by zero or more
  * [_ManagerStub]s.
- *
+ * TODO(ahe): The _ManagerStub concept is broken.  It was an attempt
+ * to create a common interface between the native Worker class and
+ * _MainManagerStub.
  */
 
 /**
@@ -183,10 +185,10 @@ class _Manager {
   Map<int, _IsolateContext> isolates;
 
   /** Reference to the main [_Manager].  Null in the main [_Manager] itself. */
-  _ManagerStub mainManager;
+  _MainManagerStub mainManager;
 
-  /** Registry of active [_ManagerStub]s.  Only used in the main [_Manager]. */
-  Map<int, _ManagerStub> managers;
+  /// Registry of active Web Workers.  Only used in the main [_Manager].
+  Map<int, dynamic /* Worker */> managers;
 
   /** The entry point given by [startRootIsolate]. */
   final Function entry;
@@ -195,7 +197,7 @@ class _Manager {
     _nativeDetectEnvironment();
     topEventLoop = new _EventLoop();
     isolates = new Map<int, _IsolateContext>();
-    managers = new Map<int, _ManagerStub>();
+    managers = new Map<int, dynamic>();
     if (isWorker) {  // "if we are not the main manager ourself" is the intent.
       mainManager = new _MainManagerStub();
       _nativeInitWorkerMessageHandler();
@@ -390,41 +392,17 @@ class _IsolateEvent {
   }
 }
 
-/** An interface for a stub used to interact with a manager. */
-abstract class _ManagerStub {
-  get id;
-  void set id(int i);
-  void set onmessage(Function f);
-  void postMessage(msg);
-  void terminate();
-}
-
 /** A stub for interacting with the main manager. */
-class _MainManagerStub implements _ManagerStub {
-  get id => 0;
-  void set id(int i) { throw new UnimplementedError(); }
-  void set onmessage(f) {
-    throw new Exception("onmessage should not be set on MainManagerStub");
-  }
+class _MainManagerStub {
   void postMessage(msg) {
-    JS("void", r"#.postMessage(#)", globalThis, msg);
+    // "self" is a way to refer to the global context object that
+    // works in HTML pages and in Web Workers.  It does not work in d8
+    // and Firefox jsshell, because that would have been too easy.
+    //
+    // See: http://www.w3.org/TR/workers/#the-global-scope
+    // and: http://www.w3.org/TR/Window/#dfn-self-attribute
+    JS("void", r"self.postMessage(#)", msg);
   }
-  void terminate() {}  // Nothing useful to do here.
-}
-
-/**
- * A stub for interacting with a manager built on a web worker. This
- * definition uses a 'hidden' type (* prefix on the native name) to
- * enforce that the type is defined dynamically only when web workers
- * are actually available.
- */
-// @Native("*Worker");
-class _WorkerStub implements _ManagerStub {
-  get id => JS("", "#.id", this);
-  void set id(i) { JS("void", "#.id = #", this, i); }
-  void set onmessage(f) { JS("void", "#.onmessage = #", this, f); }
-  void postMessage(msg) { JS("void", "#.postMessage(#)", this, msg); }
-  void terminate() { JS("void", "#.terminate()", this); }
 }
 
 const String _SPAWNED_SIGNAL = "spawned";
@@ -439,6 +417,9 @@ class IsolateNatives {
 
   static String thisScript = computeThisScript();
 
+  /// Associates an ID with a native worker object.
+  static final Expando<int> workerIds = new Expando<int>();
+
   /**
    * The src url for the script tag that loaded this code. Used to create
    * JavaScript workers.
@@ -488,9 +469,6 @@ class IsolateNatives {
 
   static computeGlobalThis() => JS('', 'function() { return this; }()');
 
-  /** Starts a new worker with the given URL. */
-  static _WorkerStub _newWorker(url) => JS("_WorkerStub", r"new Worker(#)", url);
-
   /**
    * Assume that [e] is a browser message event and extract its message data.
    * We don't import the dom explicitly so, when workers are disabled, this
@@ -502,7 +480,7 @@ class IsolateNatives {
    * Process messages on a worker, either to control the worker instance or to
    * pass messages along to the isolate running in the worker.
    */
-  static void _processWorkerMessage(sender, e) {
+  static void _processWorkerMessage(/* Worker */ sender, e) {
     var msg = _deserializeMessage(_getEventData(e));
     switch (msg['command']) {
       case 'start':
@@ -537,9 +515,8 @@ class IsolateNatives {
         _globalState.topEventLoop.run();
         break;
       case 'close':
-        _log("Closing Worker");
-        _globalState.managers.remove(sender.id);
-        sender.terminate();
+        _globalState.managers.remove(workerIds[sender]);
+        JS('void', '#.terminate()', sender);
         _globalState.topEventLoop.run();
         break;
       case 'log':
@@ -675,24 +652,26 @@ class IsolateNatives {
    */
   static void _spawnWorker(functionName, uri, replyPort) {
     if (uri == null) uri = thisScript;
-    final worker = _newWorker(uri);
-    worker.onmessage = JS('',
-                          'function(e) { #(#, e); }',
-                          DART_CLOSURE_TO_JS(_processWorkerMessage),
-                          worker);
+    final worker = JS('var', 'new Worker(#)', uri);
+
+    var processWorkerMessageTrampoline =
+      JS('', 'function(e) { #(#, e); }',
+         DART_CLOSURE_TO_JS(_processWorkerMessage),
+         worker);
+    JS('void', '#.onmessage = #', worker, processWorkerMessageTrampoline);
     var workerId = _globalState.nextManagerId++;
     // We also store the id on the worker itself so that we can unregister it.
-    worker.id = workerId;
+    workerIds[worker] = workerId;
     _globalState.managers[workerId] = worker;
-    worker.postMessage(_serializeMessage({
-      'command': 'start',
-      '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 }));
+    JS('void', '#.postMessage(#)', worker, _serializeMessage({
+        'command': 'start',
+        '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 }));
   }
 }
 
@@ -807,9 +786,9 @@ class _WorkerSendPort extends _BaseSendPort implements SendPort {
         _globalState.mainManager.postMessage(workerMessage);
       } else {
         // Deliver the message only if the worker is still alive.
-        _ManagerStub manager = _globalState.managers[_workerId];
+        /* Worker */ var manager = _globalState.managers[_workerId];
         if (manager != null) {
-          manager.postMessage(workerMessage);
+          JS('void', '#.postMessage(#)', manager, workerMessage);
         }
       }
     });