Bug 1109390 part 16 - Update IsCurrent to take a player parameter; r=jwatt

In preparation for introducing IsInPlay (where "in play" is a term in the Web
Animations spec), this patch aligns the existing IsCurrent with the definition
in the spec that says an animation effect is only current if it is attached
to an animation (player in our current naming) that is not finished. In order
to ensure that we need to pass the animation/player into the method.

This actually changes the behavior of IsCurrent since now we will return false
for animations that are finished. As far as I can tell, all the call sites that
are requesting current animations should only be concerned with animations that
are actually running. If not, they need to be adjusted to look for animations
that are either current or in effect.

dom/animation/Animation.cpp

@@ -229,10 +229,12 @@ Animation::ActiveDuration(const AnimationTiming& aTiming)
     aTiming.mIterationDuration.MultDouble(aTiming.mIterationCount));
 }
 
+// http://w3c.github.io/web-animations/#current
 bool
-Animation::IsCurrent() const
+Animation::IsCurrent(const AnimationPlayer& aPlayer) const
 {
-  if (IsFinishedTransition()) {
+  if (IsFinishedTransition() ||
+      aPlayer.PlayState() == AnimationPlayState::Finished) {
     return false;
   }
 

dom/animation/Animation.h

@@ -302,7 +302,7 @@ public:
     mIsFinishedTransition = true;
   }
 
-  bool IsCurrent() const;
+  bool IsCurrent(const AnimationPlayer& aPlayer) const;
   bool IsInEffect() const;
 
   const AnimationProperty*

dom/animation/AnimationPlayer.h

@@ -205,7 +205,7 @@ public:
 
   bool HasCurrentSource() const
   {
-    return GetSource() && GetSource()->IsCurrent();
+    return GetSource() && GetSource()->IsCurrent(*this);
   }
   bool HasInEffectSource() const
   {

layout/style/AnimationCommon.cpp

@@ -854,8 +854,11 @@ AnimationPlayerCollection::HasCurrentAnimationsForProperty(nsCSSProperty
                                                              aProperty) const
 {
   for (size_t playerIdx = mPlayers.Length(); playerIdx-- != 0; ) {
-    const Animation* anim = mPlayers[playerIdx]->GetSource();
-    if (anim && anim->IsCurrent() && anim->HasAnimationOfProperty(aProperty)) {
+    const AnimationPlayer& player = *mPlayers[playerIdx];
+    const Animation* anim = player.GetSource();
+    if (anim &&
+        anim->IsCurrent(player) &&
+        anim->HasAnimationOfProperty(aProperty)) {
       return true;
     }
   }