Bug 936720 (Part 1) - Add a new mochitest for animated image operators. r=tn

--HG--
extra : rebase_source : f3db726b4deffa7304f0cf0123d26bba680bdcfd
Bug 938124 - Add mprotect mechanism indicating which GC heap accesses made during Ion compilation are threadsafe, r=jandem.
Bug 935228 - Toggle debug traps only in debug mode. (r=jandem)