Prepare for per thread heap on service worker thread.

third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.cpp

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 67 matching lines @@
 
 ServiceWorkerGlobalScopeProxy::~ServiceWorkerGlobalScopeProxy()
 {
     // Verify that the proxy has been detached.
     DCHECK(!m_embeddedWorker);
 }
 
 DEFINE_TRACE(ServiceWorkerGlobalScopeProxy)
 {
     visitor->trace(m_document);
-    visitor->trace(m_workerGlobalScope);
 }
 
 void ServiceWorkerGlobalScopeProxy::setRegistration(std::unique_ptr<WebServiceWorkerRegistration::Handle> handle)
 {
     workerGlobalScope()->setRegistration(std::move(handle));
 }
 
 void ServiceWorkerGlobalScopeProxy::dispatchActivateEvent(int eventID)
 {
     WaitUntilObserver* observer = WaitUntilObserver::create(workerGlobalScope(), WaitUntilObserver::Activate, eventID);
@@ skipping 234 matching lines @@
     return *m_document;
 }
 
 ServiceWorkerGlobalScope* ServiceWorkerGlobalScopeProxy::workerGlobalScope() const
 {
     DCHECK(m_workerGlobalScope);
     return m_workerGlobalScope;
 }
 
 } // namespace blink