Get rid of [Callback] extended attribute for parameters in IDL files

Source/modules/webaudio/AudioContext.idl

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  * Copyright (C) 2011 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
@@ skipping 30 matching lines @@
     // All panning is relative to this listener.
     readonly attribute AudioListener listener;
 
     // Number of AudioBufferSourceNodes that are currently playing.
     readonly attribute unsigned long activeSourceCount;
     
     [RaisesException] AudioBuffer createBuffer(unsigned long numberOfChannels, unsigned long numberOfFrames, float sampleRate);
     [RaisesException] AudioBuffer createBuffer(ArrayBuffer? buffer, boolean mixToMono);
 
     // Asynchronous audio file data decoding.
-    [RaisesException] void decodeAudioData(ArrayBuffer audioData, [Callback] AudioBufferCallback successCallback, [Callback] optional AudioBufferCallback errorCallback);
+    [RaisesException] void decodeAudioData(ArrayBuffer audioData, AudioBufferCallback successCallback, optional AudioBufferCallback errorCallback);
 
     // Sources
     AudioBufferSourceNode createBufferSource();
 
     [RaisesException] MediaElementAudioSourceNode createMediaElementSource(HTMLMediaElement mediaElement);
 
 #if defined(ENABLE_MEDIA_STREAM) && ENABLE_MEDIA_STREAM
     [RaisesException] MediaStreamAudioSourceNode createMediaStreamSource(MediaStream mediaStream);
     MediaStreamAudioDestinationNode createMediaStreamDestination();
 #endif
@@ skipping 19 matching lines @@
     // void prepareOfflineBufferRendering(unsigned long numberOfChannels, unsigned long numberOfFrames, float sampleRate);
     attribute EventListener oncomplete;
     void startRendering();
 
     [MeasureAs=LegacyWebAudio, ImplementedAs=createGain] GainNode createGainNode();
     [MeasureAs=LegacyWebAudio, ImplementedAs=createDelay, RaisesException] DelayNode createDelayNode(optional double maxDelayTime);
 
     [MeasureAs=LegacyWebAudio, ImplementedAs=createScriptProcessor, RaisesException] ScriptProcessorNode createJavaScriptNode(unsigned long bufferSize, optional unsigned long numberOfInputChannels, optional unsigned long numberOfOutputChannels);
 
 };