Implemented additive animations for length

Source/core/animation/AnimationStack.cpp

Index: Source/core/animation/AnimationStack.cpp
diff --git a/Source/core/animation/AnimationStack.cpp b/Source/core/animation/AnimationStack.cpp
index 178d1d9013beb52df4df83a6bc2de26632b46eca..bb92b571638bcdb1e15ef3804976546df05c01f1 100644
--- a/Source/core/animation/AnimationStack.cpp
+++ b/Source/core/animation/AnimationStack.cpp
@@ -42,10 +42,22 @@ namespace blink {
 
 namespace {
 
-void copyToActiveInterpolationMap(const WillBeHeapVector<RefPtrWillBeMember<blink::Interpolation> >& source, WillBeHeapHashMap<CSSPropertyID, RefPtrWillBeMember<blink::Interpolation> >& target)
+void copyToActiveInterpolationMap(const WillBeHeapVector<RefPtrWillBeMember<blink::Interpolation>>& source, InterpolationPipelineMap& target)
 {
     for (const auto& interpolation : source) {
-        target.set(toStyleInterpolation(interpolation.get())->id(), interpolation.get());
+        CSSPropertyID property = toStyleInterpolation(interpolation.get())->id();
+
+        if (!target.contains(property))
+            target.set(property, InterpolationPipeline());
+
+        InterpolationPipelineMap::iterator it = target.find(property);
+        InterpolationPipeline& pipeline = it->value;
+
+        // Flush pipeline for a replace -> replace interpolation
+        if (!pipeline.isEmpty() && interpolation->isReplaceOnly())

[alancutter (OOO until 2018), 2015/02/17 03:50:56]

This should be checking for cachedUnderlyingFraction == 0 to match the logic in
applyAnimatedProperties().

+            pipeline.clear();
+
+        pipeline.append(interpolation);
     }
 }
 
@@ -55,7 +67,7 @@ bool compareEffects(const OwnPtrWillBeMember<SampledEffect>& effect1, const OwnP
     return effect1->sequenceNumber() < effect2->sequenceNumber();
 }
 
-void copyNewAnimationsToActiveInterpolationMap(const WillBeHeapVector<RawPtrWillBeMember<InertAnimation> >& newAnimations, WillBeHeapHashMap<CSSPropertyID, RefPtrWillBeMember<Interpolation> >& result)
+void copyNewAnimationsToActiveInterpolationMap(const WillBeHeapVector<RawPtrWillBeMember<InertAnimation>>& newAnimations, InterpolationPipelineMap& result)
 {
     for (const auto& newAnimation : newAnimations) {
         OwnPtrWillBeRawPtr<WillBeHeapVector<RefPtrWillBeMember<Interpolation>>> sample = nullptr;
@@ -89,14 +101,14 @@ bool AnimationStack::hasActiveAnimationsOnCompositor(CSSPropertyID property) con
     return false;
 }
 
-WillBeHeapHashMap<CSSPropertyID, RefPtrWillBeMember<Interpolation> > AnimationStack::activeInterpolations(AnimationStack* animationStack, const WillBeHeapVector<RawPtrWillBeMember<InertAnimation> >* newAnimations, const WillBeHeapHashSet<RawPtrWillBeMember<const AnimationPlayer> >* suppressedAnimationPlayers, Animation::Priority priority, double timelineCurrentTime)
+InterpolationPipelineMap 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;
+    InterpolationPipelineMap result;
 
     if (animationStack) {
-        WillBeHeapVector<OwnPtrWillBeMember<SampledEffect> >& effects = animationStack->m_effects;
+        WillBeHeapVector<OwnPtrWillBeMember<SampledEffect>>& effects = animationStack->m_effects;
         // std::sort doesn't work with OwnPtrs
         nonCopyingSort(effects.begin(), effects.end(), compareEffects);
         animationStack->simplifyEffects();