Reduce repetitive EventTarget subclassing

Source/core/dom/MessagePort.cpp

 /*
  * 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 213 matching lines @@
 
     OwnPtr<MessagePortArray> portArray = adoptPtr(new MessagePortArray(channels->size()));
     for (unsigned int i = 0; i < channels->size(); ++i) {
         RefPtr<MessagePort> port = MessagePort::create(context);
         port->entangle((*channels)[i].release());
         (*portArray)[i] = port.release();
     }
     return portArray.release();
 }
 
-EventTargetData* MessagePort::eventTargetData()
-{
-    return &m_eventTargetData;
-}
-
-EventTargetData* MessagePort::ensureEventTargetData()
-{
-    return &m_eventTargetData;
-}
-
 } // namespace WebCore