Enable Oilpan by default for webaudio/

Source/modules/webaudio/AudioNodeInput.h

Index: Source/modules/webaudio/AudioNodeInput.h
diff --git a/Source/modules/webaudio/AudioNodeInput.h b/Source/modules/webaudio/AudioNodeInput.h
index c55e921d092903a8b5ab41af283b36da1c8c4046..7b094b2a917c59802c04006f08232b79f32f848b 100644
--- a/Source/modules/webaudio/AudioNodeInput.h
+++ b/Source/modules/webaudio/AudioNodeInput.h
@@ -41,7 +41,7 @@ class AudioNodeOutput;
 
 class AudioNodeInput FINAL : public AudioSummingJunction {
 public:
-    static PassOwnPtrWillBeRawPtr<AudioNodeInput> create(AudioNode&);
+    static AudioNodeInput* create(AudioNode&);
 
     // AudioSummingJunction
     virtual void trace(Visitor*) OVERRIDE;
@@ -82,13 +82,14 @@ public:
 private:
     explicit AudioNodeInput(AudioNode&);
 
-    RawPtrWillBeMember<AudioNode> m_node;
+    Member<AudioNode> m_node;
 
     // m_disabledOutputs contains the AudioNodeOutputs which are disabled (will not be processed) by the audio graph rendering.
     // But, from JavaScript's perspective, these outputs are still connected to us.
     // Generally, these represent disabled connections from "notes" which have finished playing but are not yet garbage collected.
     // Oilpan: Since items are added to the hash set by the audio thread (not registered to Oilpan),
     // we cannot use a HeapHashSet.
+    GC_PLUGIN_IGNORE("")
     HashSet<AudioNodeOutput*> m_disabledOutputs;
 
     // Called from context's audio thread.