Bug 886546 - implement metro debug actors for developer tools.r=sfoster
Bug 855130 - Implement HTMLVideoElement's VideoPlaybackQuality (from Media Source Extensions spec).  r=roc
Bug 855130 - Implement a minimal working subset of the Media Source Extensions API.  r=roc
Bug 855130 - Drop [Creator] from HTMLVideoElement.videoPlaybackQuality attribute.  r=roc
Backout 184ef886365d, 4c6a6ac3a9d5, and 59857a435c3b on a CLOSED TREE