Make text track and cue wrapper objects dependent on their media element.

Source/core/html/track/vtt/VTTCue.idl

Index: Source/core/html/track/vtt/VTTCue.idl
diff --git a/Source/core/html/track/vtt/VTTCue.idl b/Source/core/html/track/vtt/VTTCue.idl
index 5871f0033d8230b19233b90b06765f7b6f8716e5..537f0352d6d48ca83b79aabc6c40231b0667f9a4 100644
--- a/Source/core/html/track/vtt/VTTCue.idl
+++ b/Source/core/html/track/vtt/VTTCue.idl
@@ -30,6 +30,7 @@
 [
     Constructor(double startTime, double endTime, DOMString text),
     ConstructorCallWith=Document,
+    SetWrapperReferenceFrom=owner,

[acolwell GONE FROM CHROMIUM, 2014/04/21 16:51:16]

This is needed eventhough the base class already has this? Could the result in
some sort of double counting?

[sof, 2014/04/21 18:35:01]

visitDOMWrapper() is emitted per interface, and what an interface inherits from
is not used within its implementation. So it won't be registered twice, or
something of the kind.

 ] interface VTTCue : TextTrackCue {
     [RuntimeEnabled=WebVTTRegions] attribute DOMString regionId;
     [RaisesException=Setter] attribute DOMString vertical;