Use nullptr instead of 0 in WebAudio

Source/modules/webaudio/OscillatorNode.cpp

 /*
  * Copyright (C) 2012, 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 94 matching lines @@
     else if (type == "square")
         setType(SQUARE);
     else if (type == "sawtooth")
         setType(SAWTOOTH);
     else if (type == "triangle")
         setType(TRIANGLE);
 }
 
 bool OscillatorNode::setType(unsigned type)
 {
-    PeriodicWave* periodicWave = 0;
+    PeriodicWave* periodicWave = nullptr;
     float sampleRate = this->sampleRate();
 
     switch (type) {
     case SINE: {
         DEFINE_STATIC_LOCAL(Persistent<PeriodicWave>, periodicWaveSine, (PeriodicWave::createSine(sampleRate)));
         periodicWave = periodicWaveSine;
         break;
     }
     case SQUARE: {
         DEFINE_STATIC_LOCAL(Persistent<PeriodicWave>, periodicWaveSquare, (PeriodicWave::createSquare(sampleRate)));
@@ skipping 220 matching lines @@
 {
     visitor->trace(m_frequency);
     visitor->trace(m_detune);
     visitor->trace(m_periodicWave);
     AudioScheduledSourceNode::trace(visitor);
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)