Tests that removing an active cue does not crash the browser.

** Add a text track to the video element **
** Add a cue to the track with enter event listener. **

** Play the video and remove cue when it becomes active. **
RUN(video.play())
EXPECTED (video.textTracks[0].activeCues.length == '1') OK

** Remove the cue while it is active **

No crash. PASS.

END OF TEST

