Bug 963735 - Switch from DFS -> BFS for finding GC paths, r=terrence

--HG--
extra : rebase_source : 9834e2d4815a7a1f60fd5b86843c0789674175d7
Bug 971208 - Eliminate vanilla new in SegmentedVector.h, r=mjrosenb

--HG--
extra : rebase_source : 00761e68f7821f38a46e2442870bf3d214d370f9
Bug 970253 - cx param to JS_AllocateArrayBufferContents is optional, r=terrence

--HG--
extra : rebase_source : 23adbdf985c85d3879f49578840f3e038aba4527