Prevent 'removetrack' events from firing when all inband text tracks are removed.

Source/core/html/track/TextTrackList.h

Index: Source/core/html/track/TextTrackList.h
diff --git a/Source/core/html/track/TextTrackList.h b/Source/core/html/track/TextTrackList.h
index dd5140aacd346fe7fdd67040012468c4f4c92316..6d3b3b5cb1bd4346ba8e05e39864b49de8afbce6 100644
--- a/Source/core/html/track/TextTrackList.h
+++ b/Source/core/html/track/TextTrackList.h
@@ -29,6 +29,7 @@
 #include "bindings/v8/ScriptWrappable.h"
 #include "core/events/EventListener.h"
 #include "core/events/EventTarget.h"
+#include "core/html/HTMLMediaElement.h"
 #include "platform/Timer.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
@@ -37,9 +38,7 @@
 namespace WebCore {
 
 class GenericEventQueue;
-class HTMLMediaElement;
 class TextTrack;
-class TextTrackList;
 
 class TextTrackList FINAL : public RefCounted<TextTrackList>, public ScriptWrappable, public EventTargetWithInlineData {
     REFCOUNTED_EVENT_TARGET(TextTrackList);
@@ -69,9 +68,10 @@ public:
     DEFINE_ATTRIBUTE_EVENT_LISTENER(removetrack);
 
     void clearOwnerAndClients();
-    Node* owner() const;
+    HTMLMediaElement* owner() const;
 
     void scheduleChangeEvent();
+    void removeAllInbandTracks();
 
 private:
     explicit TextTrackList(HTMLMediaElement*);