Revert of Web Animations: Remove AnimationPlayer discarding logic

Source/core/animation/AnimationStack.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 72 matching lines @@
 WillBeHeapHashMap<CSSPropertyID, RefPtrWillBeMember<Interpolation> > AnimationStack::activeInterpolations(AnimationStack* animationStack, const WillBeHeapVector<RawPtrWillBeMember<InertAnimation> >* newAnimations, const WillBeHeapHashSet<RawPtrWillBeMember<const AnimationPlayer> >* suppressedAnimationPlayers, Animation::Priority priority, double timelineCurrentTime)
 {
     // We don't exactly know when new animations will start, but timelineCurrentTime is a good estimate.
 
     WillBeHeapHashMap<CSSPropertyID, RefPtrWillBeMember<Interpolation> > result;
 
     if (animationStack) {
         WillBeHeapVector<OwnPtrWillBeMember<SampledEffect> >& effects = animationStack->m_effects;
         // std::sort doesn't work with OwnPtrs
         nonCopyingSort(effects.begin(), effects.end(), compareEffects);
+        animationStack->simplifyEffects();
         for (const auto& effect : effects) {
             if (effect->priority() != priority || (suppressedAnimationPlayers && effect->animation() && suppressedAnimationPlayers->contains(effect->animation()->player())))
                 continue;
             copyToActiveInterpolationMap(effect->interpolations(), result);
         }
     }
 
     if (newAnimations)
         copyNewAnimationsToActiveInterpolationMap(*newAnimations, result);
 
     return result;
 }
 
+void AnimationStack::simplifyEffects()
+{
+    // FIXME: This will need to be updated when we have 'add' keyframes.
+
+    BitArray<numCSSProperties> replacedProperties;
+    for (size_t i = m_effects.size(); i--; ) {
+        SampledEffect& effect = *m_effects[i];
+        effect.removeReplacedInterpolationsIfNeeded(replacedProperties);
+        if (!effect.canChange()) {
+            for (const auto& interpolation : effect.interpolations())
+                replacedProperties.set(toStyleInterpolation(interpolation.get())->id());
+        }
+    }
+
+    size_t dest = 0;
+    for (auto& effect : m_effects) {
+        if (!effect->interpolations().isEmpty()) {
+            m_effects[dest++].swap(effect);
+            continue;
+        }
+        if (effect->animation())
+            effect->animation()->notifySampledEffectRemovedFromAnimationStack();
+    }
+    m_effects.shrink(dest);
+}
+
 DEFINE_TRACE(AnimationStack)
 {
     visitor->trace(m_effects);
 }
 
 bool AnimationStack::getAnimatedBoundingBox(FloatBox& box, CSSPropertyID property) const
 {
     FloatBox originalBox(box);
     for (const auto& effect : m_effects) {
         if (effect->animation() && effect->animation()->affects(property)) {
             Animation* anim = effect->animation();
             if (!anim)
                 continue;
             const Timing& timing = anim->specifiedTiming();
             double startRange = 0;
             double endRange = 1;
             timing.timingFunction->range(&startRange, &endRange);
             FloatBox expandingBox(originalBox);
             if (!CompositorAnimations::instance()->getAnimatedBoundingBox(expandingBox, *anim->effect(), startRange, endRange))
                 return false;
             box.expandTo(expandingBox);
         }
     }
     return true;
 }
 
 } // namespace blink