Bug 1074054 part 1 - Add Animation::IsInEffect; r=dbaron

This patch adds a utility method to return if an animation is "in effect" or not
as defined by Web Animations:

  http://w3c.github.io/web-animations/#in-effect

It also moves the utility method for querying if an animation is "current"
(IsCurrent) to the .cpp file since it is fairly long. (Bug 1046055 makes one of
the callers of IsCurrent inline-able which should offset any cost introduced by
this no longer being inline-able.)

dom/animation/Animation.cpp

@@ -227,6 +227,29 @@ Animation::ActiveDuration(const AnimationTiming& aTiming)
     aTiming.mIterationDuration.MultDouble(aTiming.mIterationCount));
 }
 
+bool
+Animation::IsCurrent() const
+{
+  if (IsFinishedTransition()) {
+    return false;
+  }
+
+  ComputedTiming computedTiming = GetComputedTiming();
+  return computedTiming.mPhase == ComputedTiming::AnimationPhase_Before ||
+         computedTiming.mPhase == ComputedTiming::AnimationPhase_Active;
+}
+
+bool
+Animation::IsInEffect() const
+{
+  if (IsFinishedTransition()) {
+    return false;
+  }
+
+  ComputedTiming computedTiming = GetComputedTiming();
+  return computedTiming.mTimeFraction != ComputedTiming::kNullTimeFraction;
+}
+
 bool
 Animation::HasAnimationOfProperty(nsCSSProperty aProperty) const
 {

dom/animation/Animation.h

@@ -224,15 +224,8 @@ public:
     mIsFinishedTransition = true;
   }
 
-  bool IsCurrent() const {
+  bool IsCurrent() const;
-    if (IsFinishedTransition()) {
+  bool IsInEffect() const;
-      return false;
-    }
-
-    ComputedTiming computedTiming = GetComputedTiming();
-    return computedTiming.mPhase == ComputedTiming::AnimationPhase_Before ||
-           computedTiming.mPhase == ComputedTiming::AnimationPhase_Active;
-  }
 
   enum {
     LAST_NOTIFICATION_NONE = uint64_t(-1),