Bug 909514 - Include <new> before mozilla::Maybe (and move Maybe into mfbt/Maybe.h). r=waldo

--HG--
rename : mfbt/Util.h => mfbt/Maybe.h
Bug 909866 - Fix an exact rooting hazard in JSCompartment::wrap; r=sfink

--HG--
extra : rebase_source : 637cea3f6c93a333bfe9000f0837663fd0905853