Bug 1053130: Refactor MediaEngine video sources; alse remove Snapshot function. r=jesup,alfredo

--HG--
rename : content/media/webrtc/MediaEngineWebRTCVideo.cpp => content/media/webrtc/MediaEngineCameraVideoSource.cpp
rename : content/media/webrtc/MediaEngineWebRTC.h => content/media/webrtc/MediaEngineCameraVideoSource.h
rename : content/media/webrtc/MediaEngineWebRTCVideo.cpp => content/media/webrtc/MediaEngineGonkVideoSource.cpp
rename : content/media/webrtc/MediaEngineWebRTC.h => content/media/webrtc/MediaEngineGonkVideoSource.h
b=1080958 end current SourceBufferResource before Shutdown of TrackBuffer::mTaskQueue r=kinetik

--HG--
extra : rebase_source : fa2c7ca8138b666508f09badb907b4c420b8f9f8
b=1080958 enable config-change-webm tests

--HG--
extra : rebase_source : 0353a025b935debbf9e1200ab1d029a6e16f549e
Bug 879717: Part 1: Delay HAVE_CURRENT_DATA state until a video frame has been stored in the image container. r=roc
Bug 879717: Part 2: Add mochitest for canvas drawImage with video.mozSrcObject=stream r=roc
Bug 879717: Part 3: Fix camera preview stream and wake locks from lock screen. r=roc
Bug 1070127 - add placeholder tracks at DOMMediaStream creation. r=roc,jesup
Bug 1070127: refactor TrackUnionStream into cpp to unconfuse lldb debugger r=roc

--HG--
rename : content/media/TrackUnionStream.h => content/media/TrackUnionStream.cpp
Change a couple comments to MOZ_ASSERT from the removed JS_ASSERT.  No bug, r=trivial
Bug 999651 - Test for typed array data-inlining code invalidation on ArrayBuffer neutering, where the typed array's data pointer remains unchanged.  r=sfink
Bug 995679 - Test for length-inlining code invalidation on ArrayBuffer neutering.  r=sfink
Bug 1009952 - Tests for {g,s}etElemTryTypedStatic failing to watch out for neutering.  r=sfink
Bug 1011007 - MTypedArrayLength hoisting test.  r=jandem
Bug 991981 - Test for %TypedArray%.prototype.copyWithin.  r=sfink
Bug 991981 - Test for DataView.prototype.set* with neutering during arguments parsing.  r=sfink
Bug 991981 - new DataView() index handling test.  r=sfink
Bug 991981 - Test for ArrayBuffer.prototype.slice.  r=sfink
Bug 991981 - %TypedArray%.prototype.subarray test.  r=sfink
Bug 991981 - Test for asm.js ArrayBuffer heap neutering during arguments coercion.  r=luke
Bug 991981 - Test for typedArray.set(arraylike, offset) not asserting when arraylike.length neuters typedArray.  r=sfink