Tests negative timestamps.

Test that cues with negative startTime are not added:
EXPECTED (testTrack.track.cues.length == '4') OK
RUN(textCue = new TextTrackCue('sausage-cue', -3439332606, 3.4, 'Sausage?'))
RUN(testTrack.track.addCue(textCue))
EXPECTED (testTrack.track.cues.length == '4') OK

Test that cues with negative startTime and negative endTime are not added:
EXPECTED (testTrack.track.cues.length == '4') OK
RUN(textCue = new TextTrackCue('pepperoni-cue', -110, -3.4, 'Pepperoni?'))
RUN(testTrack.track.addCue(textCue))
EXPECTED (testTrack.track.cues.length == '4') OK

Test that setting startTime and endTime to negative values does not affect the value:
EXPECTED (testTrack.track.cues[3].startTime == '121') OK
RUN(testTrack.track.cues[3].startTime = -5)
EXPECTED (testTrack.track.cues[3].startTime == '121') OK
EXPECTED (testTrack.track.cues[3].endTime == '361200.5') OK
RUN(testTrack.track.cues[3].endTime = -3439332606)
EXPECTED (testTrack.track.cues[3].endTime == '361200.5') OK
END OF TEST

