Remove ActiveDOMObject::willStop, and introduce WorkerGlobalScope::TerminationObserver.

Source/core/workers/WorkerThread.cpp

 /*
  * Copyright (C) 2008 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 214 matching lines @@
     // Mutex protection is necessary because stop() can be called before the context is fully created.
     MutexLocker lock(m_threadCreationMutex);
 
     // Signal the thread to notify that the thread's stopping.
     if (m_shutdownEvent)
         m_shutdownEvent->signal();
 
     // Ensure that tasks are being handled by thread event loop. If script execution weren't forbidden, a while(1) loop in JS could keep the thread alive forever.
     if (m_workerGlobalScope) {
         m_workerGlobalScope->script()->scheduleExecutionTermination();
-        m_workerGlobalScope->willStopActiveDOMObjects();
+        m_workerGlobalScope->wasRequestedToTerminate();
         m_runLoop.postTaskAndTerminate(WorkerThreadShutdownStartTask::create());
         return;
     }
     m_runLoop.terminate();
 }
 
 bool WorkerThread::isCurrentThread() const
 {
     return m_threadID == currentThread();
 }
 
 class ReleaseFastMallocFreeMemoryTask : public ExecutionContextTask {
     virtual void performTask(ExecutionContext*) OVERRIDE { WTF::releaseFastMallocFreeMemory(); }
 };
 
 } // namespace WebCore