Have the Worker destructor handle non-started Workers better.

Source/core/workers/Worker.cpp

 /*
  * Copyright (C) 2008, 2010 Apple Inc. All Rights Reserved.
  * Copyright (C) 2009 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 64 matching lines @@
 
     worker->m_scriptLoader = WorkerScriptLoader::create();
     worker->m_scriptLoader->loadAsynchronously(*context, scriptURL, DenyCrossOriginRequests, worker.get());
     worker->m_contextProxy = proxyProvider->createWorkerGlobalScopeProxy(worker.get());
     return worker.release();
 }
 
 Worker::~Worker()
 {
     ASSERT(isMainThread());
+    if (!m_contextProxy)
+        return;
     ASSERT(executionContext()); // The context is protected by worker context proxy, so it cannot be destroyed while a Worker exists.
-    if (m_contextProxy)
-        m_contextProxy->workerObjectDestroyed();
+    m_contextProxy->workerObjectDestroyed();
 }
 
 const AtomicString& Worker::interfaceName() const
 {
     return EventTargetNames::Worker;
 }
 
 void Worker::postMessage(PassRefPtr<SerializedScriptValue> message, const MessagePortArray* ports, ExceptionState& exceptionState)
 {
+    ASSERT(m_contextProxy);
     // Disentangle the port in preparation for sending it to the remote context.
     OwnPtr<MessagePortChannelArray> channels = MessagePort::disentanglePorts(ports, exceptionState);
     if (exceptionState.hadException())
         return;
     m_contextProxy->postMessageToWorkerGlobalScope(message, channels.release());
 }
 
 void Worker::terminate()
 {
     if (m_contextProxy)
         m_contextProxy->terminateWorkerGlobalScope();
 }
 
 void Worker::stop()
 {
     terminate();
 }
 
 bool Worker::hasPendingActivity() const
 {
-    return m_contextProxy->hasPendingActivity() || ActiveDOMObject::hasPendingActivity();
+    return (m_contextProxy && m_contextProxy->hasPendingActivity()) || ActiveDOMObject::hasPendingActivity();
 }
 
 void Worker::didReceiveResponse(unsigned long identifier, const ResourceResponse&)
 {
     InspectorInstrumentation::didReceiveScriptResponse(executionContext(), identifier);
 }
 
 void Worker::notifyFinished()
 {
     if (m_scriptLoader->failed()) {
         dispatchEvent(Event::createCancelable(EventTypeNames::error));
     } else {
+        ASSERT(m_contextProxy);
         WorkerThreadStartMode startMode = DontPauseWorkerGlobalScopeOnStart;
         if (InspectorInstrumentation::shouldPauseDedicatedWorkerOnStart(executionContext()))
             startMode = PauseWorkerGlobalScopeOnStart;
         m_contextProxy->startWorkerGlobalScope(m_scriptLoader->url(), executionContext()->userAgent(m_scriptLoader->url()), m_scriptLoader->script(), startMode);
         InspectorInstrumentation::scriptImported(executionContext(), m_scriptLoader->identifier(), m_scriptLoader->script());
     }
     m_scriptLoader = nullptr;
 
     unsetPendingActivity(this);
 }
 
 void Worker::trace(Visitor* visitor)
 {
     AbstractWorker::trace(visitor);
 }
 
 } // namespace WebCore