Reduce repetitive EventTarget subclassing

Source/core/page/Performance.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 230 matching lines @@
 
     if (isResourceTimingBufferFull())
         dispatchEvent(Event::create(EventTypeNames::webkitresourcetimingbufferfull));
 }
 
 bool Performance::isResourceTimingBufferFull()
 {
     return m_resourceTimingBuffer.size() >= m_resourceTimingBufferSize;
 }
 
-EventTargetData* Performance::eventTargetData()
-{
-    return &m_eventTargetData;
-}
-
-EventTargetData* Performance::ensureEventTargetData()
-{
-    return &m_eventTargetData;
-}
-
 void Performance::mark(const String& markName, ExceptionState& es)
 {
     if (!m_userTiming)
         m_userTiming = UserTiming::create(this);
     m_userTiming->mark(markName, es);
 }
 
 void Performance::clearMarks(const String& markName)
 {
     if (!m_userTiming)
@@ skipping 14 matching lines @@
         m_userTiming = UserTiming::create(this);
     m_userTiming->clearMeasures(measureName);
 }
 
 double Performance::now() const
 {
     return 1000.0 * (monotonicallyIncreasingTime() - m_referenceTime);
 }
 
 } // namespace WebCore