Inherit EventTarget interface instead of duplicating its code

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 30 matching lines @@
 namespace WebCore {
 
 class Event;
 class Frame;
 class MessagePort;
 class ScriptExecutionContext;
 
 // The overwhelmingly common case is sending a single port, so handle that efficiently with an inline buffer of size 1.
 typedef Vector<RefPtr<MessagePort>, 1> MessagePortArray;
 
-class MessagePort : public RefCounted<MessagePort>, public ScriptWrappable, public EventTarget {
+class MessagePort : public EventTarget, public RefCounted<MessagePort>, public ScriptWrappable {
 public:
     static PassRefPtr<MessagePort> create(ScriptExecutionContext& scriptExecutionContext) { return adoptRef(new MessagePort(scriptExecutionContext)); }
     virtual ~MessagePort();
 
     void postMessage(PassRefPtr<SerializedScriptValue> message, const MessagePortArray*, ExceptionCode&);
 
     void start();
     void close();
 
     void entangle(PassOwnPtr<MessagePortChannel>);
@@ skipping 51 matching lines @@
     bool m_started;
     bool m_closed;
 
     ScriptExecutionContext* m_scriptExecutionContext;
     EventTargetData m_eventTargetData;
 };
 
 } // namespace WebCore
 
 #endif // MessagePort_h