Enable Oilpan by default for webaudio/

Source/modules/webaudio/AudioNodeOutput.cpp

Index: Source/modules/webaudio/AudioNodeOutput.cpp
diff --git a/Source/modules/webaudio/AudioNodeOutput.cpp b/Source/modules/webaudio/AudioNodeOutput.cpp
index c7f90ac08a188f426d9de39c1cacb9d4d476394b..5bb93ec92cc64920dec20a7cb49c63b6a338f63a 100644
--- a/Source/modules/webaudio/AudioNodeOutput.cpp
+++ b/Source/modules/webaudio/AudioNodeOutput.cpp
@@ -48,18 +48,16 @@ inline AudioNodeOutput::AudioNodeOutput(AudioNode* node, unsigned numberOfChanne
     m_internalBus = AudioBus::create(numberOfChannels, AudioNode::ProcessingSizeInFrames);
 }
 
-PassOwnPtrWillBeRawPtr<AudioNodeOutput> AudioNodeOutput::create(AudioNode* node, unsigned numberOfChannels)
+AudioNodeOutput* AudioNodeOutput::create(AudioNode* node, unsigned numberOfChannels)
 {
-    return adoptPtrWillBeNoop(new AudioNodeOutput(node, numberOfChannels));
+    return new AudioNodeOutput(node, numberOfChannels);
 }
 
 void AudioNodeOutput::trace(Visitor* visitor)
 {
-#if ENABLE(OILPAN)
     visitor->trace(m_node);
     visitor->trace(m_inputs);
     visitor->trace(m_params);
-#endif
 }
 
 void AudioNodeOutput::setNumberOfChannels(unsigned numberOfChannels)