Remove duplicated headers from core/

Source/core/events/MessageEvent.cpp

 /*
  * Copyright (C) 2007 Henry Mason (hmason@mac.com)
  * Copyright (C) 2003, 2005, 2006, 2007, 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
@@ skipping 11 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  */
 
 #include "config.h"
 #include "core/events/MessageEvent.h"
 
 #include "core/events/ThreadLocalEventNames.h"
-#include "core/frame/DOMWindow.h"
 
 namespace WebCore {
 
 static inline bool isValidSource(EventTarget* source)
 {
     return !source || source->toDOMWindow() || source->toMessagePort();
 }
 
 MessageEventInit::MessageEventInit()
 {
@@ skipping 126 matching lines @@
 {
     return EventNames::MessageEvent;
 }
 
 void MessageEvent::entangleMessagePorts(ExecutionContext* context)
 {
     m_ports = MessagePort::entanglePorts(*context, m_channels.release());
 }
 
 } // namespace WebCore