Oilpan: Use transition types for HTMLMediaElement and make AudioSourceProviderClient a GC mixin.

Source/modules/webaudio/MediaElementAudioSourceNode.cpp

Index: Source/modules/webaudio/MediaElementAudioSourceNode.cpp
diff --git a/Source/modules/webaudio/MediaElementAudioSourceNode.cpp b/Source/modules/webaudio/MediaElementAudioSourceNode.cpp
index 2b4bb42e78c33ffb997d68873cb345b8b8e3e718..ac3f7443b93af7d090634808c65838e122ffc711 100644
--- a/Source/modules/webaudio/MediaElementAudioSourceNode.cpp
+++ b/Source/modules/webaudio/MediaElementAudioSourceNode.cpp
@@ -63,7 +63,9 @@ MediaElementAudioSourceNode::MediaElementAudioSourceNode(AudioContext* context,
 
 MediaElementAudioSourceNode::~MediaElementAudioSourceNode()
 {
+#if !ENABLE(OILPAN)
     m_mediaElement->setAudioSourceNode(0);
+#endif
     uninitialize();
 }
 
@@ -148,6 +150,13 @@ void MediaElementAudioSourceNode::unlock()
     deref();
 }
 
+void MediaElementAudioSourceNode::trace(Visitor* visitor)
+{
+    visitor->trace(m_mediaElement);
+    AudioSourceNode::trace(visitor);
+    AudioSourceProviderClient::trace(visitor);
+}
+
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)