Use nullptr instead of 0 in WebAudio

Source/modules/webaudio/AudioNode.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 165 matching lines @@
 
 void AudioNode::addOutput(AudioNodeOutput* output)
 {
     m_outputs.append(output);
 }
 
 AudioNodeInput* AudioNode::input(unsigned i)
 {
     if (i < m_inputs.size())
         return m_inputs[i].get();
-    return 0;
+    return nullptr;
 }
 
 AudioNodeOutput* AudioNode::output(unsigned i)
 {
     if (i < m_outputs.size())
         return m_outputs[i].get();
-    return 0;
+    return nullptr;
 }
 
 void AudioNode::connect(AudioNode* destination, unsigned outputIndex, unsigned inputIndex, ExceptionState& exceptionState)
 {
     ASSERT(isMainThread());
     AudioContext::AutoLocker locker(context());
 
     if (context()->isContextClosed()) {
         exceptionState.throwDOMException(
             InvalidStateError,
@@ skipping 399 matching lines @@
 
 void AudioNode::updateChannelCountMode()
 {
     m_channelCountMode = m_newChannelCountMode;
     updateChannelsForInputs();
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)