import changes from `dev' branch of rmottola/Arctic-Fox:

- Bug 1187811 - Remove unused epoch time from RunFrameRequestCallbacks. r=bkelly (1b95c8766)
- remove kungFuDeathGrip (639834f5d)
- Bug 1180125 part 1 - Queue and dispatch CSS animation events as a separate step; r=dbaron (89880dbaf)
- Bug 1164330 - Rename time fraction to (iteration) progress; r=jwatt (0ddb9ef76)
- Bug 1139272 - Allow expensive style context assertions to be enabled with a pref. r=dbaron (943209ace)
- missing bit of Bug 847287 patch 3 (64b4c7288)
- Bug 1180125 part 2 - Move AnimationCommon classes out of CSS namespace; r=dbaron (205a71934)
- Bug 1189630 - Make browser_translation_exceptions.js wait for infobar to finish animating; r=florian (732c4657b)
- Bug 1180125 part 1b - Hook nsAnimationManager's list of events up to the cycle collector; r=dbaron (2733b7526)
- Bug 1180125 part 3 - Extract DelayedEventDispatcher; r=dbaron (0d42b1d87)
- Bug 1180125 part 4 - Move PseudoTypeAsString to AnimationCollection and reuse; r=dbaron (7acbc714c)
- Bug 1180125 part 5 - Move TransitionEventInfo to nsTransitionManager.h; r=dbaron (cac03f9f6)
- Bug 1180125 part 6 - Use DelayedEventDispatcher in nsTransitionManager; r=dbaron (bd0d834f1)
- Bug 1180125 part 7 - Queue transition events from CSSTransition::Tick; r=dbaron (e9f503aff)
- Bug 1180125 part 8 - Dispatch transition events from refresh driver; r=dbaron (90ebddaad)
- Bug 1196378 - js_delete should accept a const pointer like builtin delete, r=fitzgen (7342bdc0d)
- Bug 1196378 - Fix mismatched js_new/js_free in ShellPrincipals, r=fitzgen (bde74c00c)
- Bug 1199384 - Add shell function for writing a typed array to a file, r=sfink. (4086bd290)
- Bug 1215063 - Add os.path.isAbsolute() and as.path.join() shell utilities r=sfink (1706b965a)
- Bug 1161298 - missing length guard on SAB. r=bbouvier (17a168570)
- Bug 1160468 - Remove unnecessary pre-barrier when creating undepended string r=terrence (1c78c672f)

layout/base/nsPresShell.cpp

@@ -1240,6 +1240,11 @@ PresShell::Destroy()
     }
   }
 
+  if (mPresContext) {
+    mPresContext->AnimationManager()->ClearEventQueue();
+    mPresContext->TransitionManager()->ClearEventQueue();
+  }
+
   // Revoke any pending events.  We need to do this and cancel pending reflows
   // before we destroy the frame manager, since apparently frame destruction
   // sometimes spins the event queue when plug-ins are involved(!).