Bug 908923 - Part 1: Basic about:webrtc page. r=gavin
Bug 908923 - Part 2: Add a button to dump the entire rlog ringbuffer to about:webrtc. r=abr
Bug 908923 - Part 3: Disable auto-refresh in about:webrtc to cut down on jank. r=abr
Bug 957847 - Fix VTTCue crash at TextTrackCue::AddCue. r=rillian