Backed out 3 changesets (bug 1509316) for MDA failures on dom/media/tests/mochitest/test_peerConnection_captureStream_canvas_2d.html

Backed out changeset d64c35b9c211 (bug 1509316)
Backed out changeset 817f14af91f0 (bug 1509316)
Backed out changeset b4bee18bb499 (bug 1509316)