Remove VideoTrack runtime feature since we always support TextTracks.

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

 /*
  * Copyright (c) 2013, Opera Software ASA. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 12 matching lines @@
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 [
     Constructor(double startTime, double endTime, DOMString text),
     ConstructorCallWith=Document,
-    RuntimeEnabled=VideoTrack,
 ] interface VTTCue : TextTrackCue {
     [RuntimeEnabled=WebVTTRegions] attribute DOMString regionId;
     [RaisesException=Setter] attribute DOMString vertical;
     attribute boolean snapToLines;
     [RaisesException=Setter] attribute long line;
     [RaisesException=Setter] attribute long position;
     [RaisesException=Setter] attribute long size;
     [RaisesException=Setter] attribute DOMString align;
     attribute DOMString text;
     DocumentFragment getCueAsHTML();
 };