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

Source/modules/webaudio/MediaStreamAudioSourceNode.cpp

Index: Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
diff --git a/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp b/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
index f413a686bb108968837f39b5053ee4059573e307..9505d5fe92e582dc70a2036ae9d7a5169ebc332c 100644
--- a/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
+++ b/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
@@ -113,6 +113,12 @@ void MediaStreamAudioSourceNode::process(size_t numberOfFrames)
     }
 }
 
+void MediaStreamAudioSourceNode::trace(Visitor* visitor)
+{
+    AudioSourceNode::trace(visitor);
+    AudioSourceProviderClient::trace(visitor);
+}
+
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)