Oilpan: Fix worker thread termination finalization order issues.

Source/core/workers/WorkerGlobalScope.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2009, 2011 Google Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 178 matching lines @@
 
 void WorkerGlobalScope::willStopActiveDOMObjects()
 {
     lifecycleNotifier().notifyWillStopActiveDOMObjects();
 }
 
 void WorkerGlobalScope::dispose()
 {
     ASSERT(thread()->isCurrentThread());
 
-    // Notify proxy that we are going away. This can free the WorkerThread object, so do not access it after this.
-    thread()->workerReportingProxy().workerGlobalScopeDestroyed();
-
     clearScript();
     clearInspector();
     setClient(0);
 
-    // The thread reference isn't currently cleared, as the execution
-    // context's thread is accessed by GCed lifetime objects when
-    // they're finalized.
-    // FIXME: oilpan: avoid by explicitly removing the WorkerGlobalScope
-    // as an observable context right here.
+    // We do not clear the thread field of the
+    // WorkerGlobalScope. Other objects keep the worker global scope
+    // alive because they need its thread field to check that work is
+    // being carried out on the right thread. We therefore cannot clear
+    // the thread field before all references to the worker global
+    // scope are gone.
 }
 
 void WorkerGlobalScope::importScripts(const Vector<String>& urls, ExceptionState& exceptionState)
 {
     ASSERT(contentSecurityPolicy());
     Vector<String>::const_iterator urlsEnd = urls.end();
     Vector<KURL> completedURLs;
     for (Vector<String>::const_iterator it = urls.begin(); it != urlsEnd; ++it) {
         const KURL& url = executionContext()->completeURL(*it);
         if (!url.isValid()) {
@@ skipping 84 matching lines @@
 {
     visitor->trace(m_console);
     visitor->trace(m_location);
     visitor->trace(m_navigator);
 #if ENABLE(OILPAN)
     HeapSupplementable<WorkerGlobalScope>::trace(visitor);
 #endif
 }
 
 } // namespace WebCore