Remove duplicated headers from core/

Source/core/workers/WorkerMessagingProxy.cpp

 /*
  * Copyright (C) 2008 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 13 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  */
 
 #include "config.h"
 
 #include "core/workers/WorkerMessagingProxy.h"
 
 #include "core/dom/CrossThreadTask.h"
 #include "core/dom/Document.h"
-#include "core/dom/ExecutionContext.h"
 #include "core/events/ErrorEvent.h"
 #include "core/events/MessageEvent.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/inspector/ScriptCallStack.h"
 #include "core/inspector/WorkerDebuggerAgent.h"
 #include "core/inspector/WorkerInspectorController.h"
 #include "core/loader/DocumentLoadTiming.h"
 #include "core/loader/DocumentLoader.h"
 #include "core/frame/ContentSecurityPolicy.h"
 #include "core/frame/DOMWindow.h"
@@ skipping 362 matching lines @@
 
     m_workerThreadHadPendingActivity = hasPendingActivity;
 }
 
 bool WorkerMessagingProxy::hasPendingActivity() const
 {
     return (m_unconfirmedMessageCount || m_workerThreadHadPendingActivity) && !m_askedToTerminate;
 }
 
 } // namespace WebCore