Backed out 35 changesets (bug 941158, bug 972518, bug 959520, bug 986063, bug 948895, bug 969387, bug 976831, bug 952530, bug 949028, bug 948075, bug 959730, bug 949398, bug 962182, bug 965782, bug 961648, bug 950729, bug 951153, bug 947205, bug 960375, bug 959517, bug 965986, bug 970996, bug 961792, bug 963598, bug 950098, bug 981568, bug 950641, bug 979338, bug 979577, bug 961874, bug 956803, bug 957248, bug 958024, bug 948992, bug 975169) for Mnw failures.

Backed out changeset 8a68f981ed16 (bug 986063)
Backed out changeset 4efb3f97ece1 (bug 959517)
Backed out changeset 0da13b961704 (bug 981568)
Backed out changeset e958cb81f404 (bug 979338)
Backed out changeset afda58d4524a (bug 979577)
Backed out changeset 1d564b5e888c (bug 976831)
Backed out changeset f6fecddd4991 (bug 975169)
Backed out changeset f9c1bd050b67 (bug 962182)
Backed out changeset 963df1c4df29 (bug 969387)
Backed out changeset 0823d2f2028e (bug 970996)
Backed out changeset 0c75feab458b (bug 972518)
Backed out changeset 93b124d3185c (bug 941158)
Backed out changeset aae39f0ae164 (bug 949028)
Backed out changeset a455fe267323 (bug 965986)
Backed out changeset 5cc63d891216 (bug 965782)
Backed out changeset f1ce1a50e612 (bug 948895)
Backed out changeset dff083680a47 (bug 952530)
Backed out changeset fea0ebbc1b6f (bug 963598)
Backed out changeset 0d4e210f7c0c (bug 959520)
Backed out changeset f624307ea69c (bug 961648)
Backed out changeset ca4425177962 (bug 948075)
Backed out changeset e185f21fe8d4 (bug 958024)
Backed out changeset 3721938dd9df (bug 961874)
Backed out changeset 5c7ec754d01a (bug 961792)
Backed out changeset 77dec4722958 (bug 960375)
Backed out changeset c603bb10bb94 (bug 959730)
Backed out changeset 8bb1b398febc (bug 956803)
Backed out changeset 2b4bf76befcc (bug 957248)
Backed out changeset 111f3dafb2ef (bug 950641)
Backed out changeset bff2422498d4 (bug 947205)
Backed out changeset bdfbcc6cc8df (bug 950098)
Backed out changeset 7d0174e7ada7 (bug 951153)
Backed out changeset 4138b5d54050 (bug 950729)
Backed out changeset deaeb813b029 (bug 949398)
Backed out changeset 2a6a4fff830f (bug 948992)
Bug 907162 - Fix MediaDecoderStateMachine might dispatch MediaDecoder::PlaybackEnded more than once and trigger multiple 'ended' events in HTMLMediaElement. r=cpearce, a=fabrice
Bug 934794 - Fix failing to update stream blocking status when endBlockingDecisions == mStateComputedTime. r=roc, a=fabrice
Bug 985827 - Make Navigator::DoNewResolve not double-create objects no matter what JS is doing. r=khuey, a=fabrice
Bug 979199 - DataStore should not dispatch events when the window is destroyed. r=ehsan, a=fabrice
Bug 985042 - DataStore.jsm removes its inner-window-destroyed observer. r=fabrice, a=fabrice