Use nullptr instead of 0 in WebAudio

Source/platform/audio/HRTFPanner.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 142 matching lines @@
     bool isAzimuthGood = azimuth >= -180.0 && azimuth <= 180.0;
     ASSERT(isAzimuthGood);
     if (!isAzimuthGood) {
         outputBus->zero();
         return;
     }
 
     // Normally, we'll just be dealing with mono sources.
     // If we have a stereo input, implement stereo panning with left source processed by left HRTF, and right source by right HRTF.
     const AudioChannel* inputChannelL = inputBus->channelByType(AudioBus::ChannelLeft);
-    const AudioChannel* inputChannelR = numInputChannels > 1 ? inputBus->channelByType(AudioBus::ChannelRight) : 0;
+    const AudioChannel* inputChannelR = numInputChannels > 1 ? inputBus->channelByType(AudioBus::ChannelRight) : nullptr;
 
     // Get source and destination pointers.
     const float* sourceL = inputChannelL->data();
     const float* sourceR = numInputChannels > 1 ? inputChannelR->data() : sourceL;
     float* destinationL = outputBus->channelByType(AudioBus::ChannelLeft)->mutableData();
     float* destinationR = outputBus->channelByType(AudioBus::ChannelRight)->mutableData();
 
     double azimuthBlend;
     int desiredAzimuthIndex = calculateDesiredAzimuthIndexAndBlend(azimuth, azimuthBlend);
 
@@ skipping 142 matching lines @@
 
 DEFINE_TRACE(HRTFPanner)
 {
     visitor->trace(m_databaseLoader);
     Panner::trace(visitor);
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)