Inherit EventTarget interface instead of duplicating its code

Source/modules/webaudio/AudioContext.h

 /*
  * Copyright (C) 2010, Google 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 55 matching lines @@
 class DynamicsCompressorNode;
 class AnalyserNode;
 class WaveShaperNode;
 class ScriptProcessorNode;
 class OscillatorNode;
 class PeriodicWave;
 
 // AudioContext is the cornerstone of the web audio API and all AudioNodes are created from it.
 // For thread safety between the audio thread and the main thread, it has a rendering graph locking mechanism.
 
-class AudioContext : public ActiveDOMObject, public ScriptWrappable, public ThreadSafeRefCounted<AudioContext>, public EventTarget {
+class AudioContext : public EventTarget, public ActiveDOMObject, public ScriptWrappable, public ThreadSafeRefCounted<AudioContext> {
 public:
     // Create an AudioContext for rendering to the audio hardware.
     static PassRefPtr<AudioContext> create(Document*);
 
     // Create an AudioContext for offline (non-realtime) rendering.
     static PassRefPtr<AudioContext> createOfflineContext(Document*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate, ExceptionCode&);
 
     virtual ~AudioContext();
 
     bool isInitialized() const;
@@ skipping 260 matching lines @@
     // It is somewhat arbitrary and could be increased if necessary.
     enum { MaxNumberOfChannels = 32 };
 
     // Number of AudioBufferSourceNodes that are active (playing).
     int m_activeSourceCount;
 };
 
 } // WebCore
 
 #endif // AudioContext_h