Bug 958489 - Implement base Image::GetAsSourceSurface. r=nical

Added an Image::GetAsSourceSurface to return a gfx::SourceSurface
and implemented in terms of gfxPlatform::GetSourceSurfaceForSurface.

Deprecated GetAsSurface.
Bug 958490 - Implement ImageContainer::Lock/GetAsCurrentSurface. r=nical

Added member functions GetCurrentAsSourceSurface and
LockCurrentAsSourceSurface to return a gfx::SourceSurface instead
of a gfxASurface.

Deprecated LockCurrentAsSurface and GetCurrentAsSurface
Bug 838509 - Part 1: Make MathML frames use GetAttr instead of GetAttribute. r=roc
Bug 838509 - Part 2: Remove mstyle presentation data and frame class. r=roc
Bug 838509 - Part 3: Update tests for mstyle/math and add more tests. r=roc
Bug 906990: Part 12. Report statistics from all components when the MediaStreamTrack is not specified. r=ekr, r=jib
Bug 906990: Part 13. Get local/remote candidates separately, instead of grabbing them from candidate pairs (means we can get candidates before pairing happens). r=ekr
Bug 906990: Part 14. Catch exceptions thrown by getStats, since this can fail in fairly innocuous circumstances. Also, do a better job of error reporting when the stats API is used on a closed PeerConnection. r=jib