Update TextTrackCue tests to use VTTCue where appropriate

LayoutTests/media/video-controls-captions-multiple-clicks.html

Index: LayoutTests/media/video-controls-captions-multiple-clicks.html
diff --git a/LayoutTests/media/video-controls-captions-multiple-clicks.html b/LayoutTests/media/video-controls-captions-multiple-clicks.html
index f898c0634b15e39c323f9a0f87da1cf7658aeb8e..30990c95cb9979b945e57a7f0ecd93eee0588fa7 100644
--- a/LayoutTests/media/video-controls-captions-multiple-clicks.html
+++ b/LayoutTests/media/video-controls-captions-multiple-clicks.html
@@ -16,7 +16,7 @@
             track = video.addTextTrack('captions');
 
             for(var i = 0; i < 3; i++) {
-                var cue = new TextTrackCue(0, 120, text[i]);
+                var cue = new VTTCue(0, 120, text[i]);
                 track.addCue(cue);
             }
         }