First part of work to move V8 binding integrity off of vtables.

Source/WebCore/Modules/mediastream/MediaStreamTrackEvent.cpp

Index: Source/WebCore/Modules/mediastream/MediaStreamTrackEvent.cpp
diff --git a/Source/WebCore/Modules/mediastream/MediaStreamTrackEvent.cpp b/Source/WebCore/Modules/mediastream/MediaStreamTrackEvent.cpp
index f62100271c1d8c69fab8f246e074529963272d6c..5f9f870be2b4aa6f0b27aa442c140cea40075562 100644
--- a/Source/WebCore/Modules/mediastream/MediaStreamTrackEvent.cpp
+++ b/Source/WebCore/Modules/mediastream/MediaStreamTrackEvent.cpp
@@ -45,12 +45,14 @@ PassRefPtr<MediaStreamTrackEvent> MediaStreamTrackEvent::create(const AtomicStri
 
 MediaStreamTrackEvent::MediaStreamTrackEvent()
 {
+    ScriptWrappable::init(this);
 }
 
 MediaStreamTrackEvent::MediaStreamTrackEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtr<MediaStreamTrack> track)
     : Event(type, canBubble, cancelable)
     , m_track(track)
 {
+    ScriptWrappable::init(this);
 }
 
 MediaStreamTrackEvent::~MediaStreamTrackEvent()