Support text track selection in video controls

LayoutTests/media/video-controls-captions-expected.txt

Index: LayoutTests/media/video-controls-captions-expected.txt
diff --git a/LayoutTests/media/video-controls-captions-expected.txt b/LayoutTests/media/video-controls-captions-expected.txt
index 750344d52e28a9c197ae93b24b48ee01f738c55d..8cb9dfa4c055064cf5c63ee7ae7a5d3dbafbb71d 100644
--- a/LayoutTests/media/video-controls-captions-expected.txt
+++ b/LayoutTests/media/video-controls-captions-expected.txt
@@ -1,4 +1,4 @@
-Tests that the closed captions button, when toggled, updates the text track display area.
+Tests that the closed captions button enables track switching
 
 EVENT(canplaythrough)
 
@@ -12,11 +12,11 @@ EXPECTED (video.textTracks.length == '1') OK
 EXPECTED (video.textTracks[0].mode == 'disabled') OK
 Failed to find text track container element
 
-** Captions track should load and captions should become visible after button is clicked **
+** Captions track should load and captions should become visible after a track is selected **
 *** Click the CC button.
 EXPECTED (textTrackDisplayElement(video, 'display').innerText == 'Lorem') OK
 
-** Captions should not be visible after button is clicked again **
+** Captions should not be visible after Off is clicked **
 *** Click the CC button.
 No text track cue with display id '-webkit-media-text-track-display' is currently visible