Backed out 9 changesets (bug 943660, bug 936964) because of ASAN use-after-free crashes on browser-chrome and mochitest-other

Backed out changeset 85486c4aa3d8 (bug 936964)
Backed out changeset 25312eb71998 (bug 936964)
Backed out changeset 6dbb8333960c (bug 936964)
Backed out changeset da6465ad476f (bug 936964)
Backed out changeset a87ffc992f38 (bug 936964)
Backed out changeset 4ae3a61182db (bug 936964)
Backed out changeset 34e9c3137804 (bug 936964)
Backed out changeset fd1459e71585 (bug 936964)
Backed out changeset 3e8a701d8bdc (bug 943660)

Landed on a CLOSED TREE

--HG--
rename : content/canvas/src/WebGLMemoryTracker.h => content/canvas/src/WebGLMemoryReporterWrapper.h
Bug 943719 - Build MFBT in unified mode; r=froydnj,djvj