Use TextTrackKind enum in HTMLMediaElement.addTextTrack IDL signature

Source/core/html/HTMLMediaElement.h

Index: Source/core/html/HTMLMediaElement.h
diff --git a/Source/core/html/HTMLMediaElement.h b/Source/core/html/HTMLMediaElement.h
index 5b56d9846b4f2ac7c497b5b023b436de45dfe956..58e62ecef28537cca1490076f6f73c1d9eb75b87 100644
--- a/Source/core/html/HTMLMediaElement.h
+++ b/Source/core/html/HTMLMediaElement.h
@@ -175,8 +175,6 @@ public:
     void selectedVideoTrackChanged(blink::WebMediaPlayer::TrackId*);
 
     PassRefPtrWillBeRawPtr<TextTrack> addTextTrack(const AtomicString& kind, const AtomicString& label, const AtomicString& language, ExceptionState&);
-    PassRefPtrWillBeRawPtr<TextTrack> addTextTrack(const AtomicString& kind, const AtomicString& label, ExceptionState& exceptionState) { return addTextTrack(kind, label, emptyAtom, exceptionState); }
-    PassRefPtrWillBeRawPtr<TextTrack> addTextTrack(const AtomicString& kind, ExceptionState& exceptionState) { return addTextTrack(kind, emptyAtom, emptyAtom, exceptionState); }
 
     TextTrackList* textTracks();
     CueList currentlyActiveCues() const { return m_currentlyActiveCues; }