Move webaudio to oilpan

Source/modules/webaudio/GainNode.cpp

 /*
  * 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 90 matching lines @@
 
     if (!isInitialized()) {
         // This will propagate the channel count to any nodes connected further downstream in the graph.
         output(0)->setNumberOfChannels(numberOfChannels);
         initialize();
     }
 
     AudioNode::checkNumberOfChannelsForInput(input);
 }
 
+void GainNode::trace(Visitor* visitor)
+{
+    visitor->trace(m_gain);
+    AudioNode::trace(visitor);
+}
+
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)