Bug 845190 - Reactivate tests blocked by bug 888347. r=yoric
Bug 875731 - Replace callers of nsIDownloadManager.usersDownloadsDirectory with Downloads.getUserDownloadsDirectory toolkit/mozapps/. r=paolo
Bug 883173 - Part 1: Rename parameter in TextTrackCue::RemoveCue and AddCue. r=rillian
Bug 883173 - Part 2: Add insertion sorting for TextTrackCueList::AddCue. r=rillian

- We expect most files to already be sorted, so an insertion sort starting from
the end of the current array should be more efficient than a general sort step
after all cues are loaded
- Added a test for insertion sorting as well.
Bug 883173 - Part 3: Implement TextTrack::ActiveCues. r=cpearce, r=rillian

- Active cues now returns the subset of cues in mCueList that are valid
for the current playback time.
- Introduces new code in media element, when seeking, and in TextTrack, when
adding and removing cues, to mark the active cue list as dirty so that we know
when we might need to rebuild the list completely.