Reduce forward declarations in core/dom

Source/core/dom/MessagePort.h

 /*
  * 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 25 matching lines @@
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
 #include "wtf/WeakPtr.h"
 
 namespace WebCore {
 
-class Event;
 class ExceptionState;
-class LocalFrame;
 class MessagePort;
 class ExecutionContext;
 class SerializedScriptValue;
 
 // The overwhelmingly common case is sending a single port, so handle that efficiently with an inline buffer of size 1.
 typedef WillBeHeapVector<RefPtrWillBeMember<MessagePort>, 1> MessagePortArray;
 
 // Not to be confused with blink::WebMessagePortChannelArray; this one uses Vector and OwnPtr instead of WebVector and raw pointers.
 typedef Vector<OwnPtr<blink::WebMessagePortChannel>, 1> MessagePortChannelArray;
 
@@ skipping 59 matching lines @@
 
     bool m_started;
     bool m_closed;
 
     WeakPtrFactory<MessagePort> m_weakFactory;
 };
 
 } // namespace WebCore
 
 #endif // MessagePort_h