Bug 1194639 part 3 - Report changes to startTime to animation mutation observers; r=heycam

dom/animation/Animation.cpp

@@ -128,6 +128,12 @@ Animation::SetTimeline(AnimationTimeline* aTimeline)
 void
 Animation::SetStartTime(const Nullable<TimeDuration>& aNewStartTime)
 {
+  if (aNewStartTime == mStartTime) {
+    return;
+  }
+
+  AutoMutationBatchForAnimation mb(*this);
+
   Nullable<TimeDuration> timelineTime;
   if (mTimeline) {
     // The spec says to check if the timeline is active (has a resolved time)
@@ -157,6 +163,9 @@ Animation::SetStartTime(const Nullable<TimeDuration>& aNewStartTime)
   }
 
   UpdateTiming(SeekFlag::NoSeek, SyncNotifyFlag::Async);
+  if (IsRelevant()) {
+    nsNodeUtils::AnimationChanged(this);
+  }
   PostUpdate();
 }
 

dom/animation/test/chrome/test_animation_observers.html

@@ -693,6 +693,7 @@ function assert_records(expected, desc) {
   // notification.
   [
     { prop: "playbackRate", val: 0.5 },
+    { prop: "startTime",    val: 50000 },
   ].forEach(function(aChangeTest) {
     addAsyncAnimTest(`single_animation_api_change_${aChangeTest.prop}`,
                      aOptions, function*() {