Bug 1093654 - Fix various memory leaks in MediaDecoders. r=jwwang

Change various function prototyping to make object ownership more explicit.
Bug 1094261: SIMD: Have lane accessors return Signed and signMask return Signed in asm.js; r=luke
Bug 1094261: SIMD: Simplify testSIMD.js; r=luke
Backed out changeset 1d058cefd04f (bug 1092096) for m2 test failures
Bug 1093028 - Imports should block DOMContentLoaded of the parent. r=mrbkap
Merge mozilla-central to mozilla-inbound
Bug 1093686 - Ignore body-level touch/mouse listeners when assessing element clickability. r=roc

When walking up the content tree to assess if an element is contained inside a
clickable element, we should stop before hitting the body element. This is a
heuristic based on pages in the wild, because a lot of pages have mouse/touch
listeners on the body. Without this patch all elements end up getting treated
as clickable which makes the event retargeting code useless.
Bug 1093686 - Add some debug logging code for PositionedEventTargeting.cpp. r=roc
Bug 1093686 - Add a test to ensure event listeners on the body don't affect event retargeting. r=roc
Bug 1093033 - Imports should update their CustomElements. r=wchen
Backed out changeset 70a72a19cb4b (bug 1093654)
Backed out changeset 1c969fba2f64 (bug 1092979)
Backed out changeset a6540a77d6f7 (bug 1065827)
Backed out changeset c0087ef95dc0 (bug 1065827)
Backed out changeset 4467ecf7bc6b (bug 1065827)
Backed out changeset 9316add97cf2 (bug 1065827)
Backed out changeset 44f27b3c35d4 (bug 1065827)
Backed out changeset aebe859551b3 (bug 1065827) for perma failures in m2 tests on a CLOSED TREE
Bug 1092096 - Separate MSE prefs for MP4 and WebM on a CLOSED TREE.  r=cajbir
Bug 1073218: remove the soft start mechanism for full Hello rollout. r=abr,Unfocused