Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/webaudio/PeriodicWave.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
@@ skipping 37 matching lines @@
 PassRefPtr<PeriodicWave> PeriodicWave::create(float sampleRate, Float32Array* real, Float32Array* imag)
 {
     bool isGood = real && imag && real->length() == imag->length();
     ASSERT(isGood);
     if (isGood) {
         RefPtr<PeriodicWave> periodicWave = adoptRef(new PeriodicWave(sampleRate));
         size_t numberOfComponents = real->length();
         periodicWave->createBandLimitedTables(real->data(), imag->data(), numberOfComponents);
         return periodicWave;
     }
-    return 0;
+    return nullptr;
 }
 
 PassRefPtr<PeriodicWave> PeriodicWave::createSine(float sampleRate)
 {
     RefPtr<PeriodicWave> periodicWave = adoptRef(new PeriodicWave(sampleRate));
     periodicWave->generateBasicWaveform(OscillatorNode::SINE);
     return periodicWave;
 }
 
 PassRefPtr<PeriodicWave> PeriodicWave::createSquare(float sampleRate)
@@ skipping 227 matching lines @@
         realP[n] = 0;
         imagP[n] = b;
     }
 
     createBandLimitedTables(realP, imagP, halfSize);
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)