Implemented additive animations for length

Source/core/animation/AnimationStack.h

 /*
  * 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 16 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef AnimationStack_h
 #define AnimationStack_h
 
 #include "core/animation/Animation.h"
 #include "core/animation/AnimationEffect.h"
 #include "core/animation/AnimationPlayer.h"
+#include "core/animation/InterpolationPipeline.h"
 #include "core/animation/SampledEffect.h"
 #include "platform/geometry/FloatBox.h"
 #include "wtf/HashSet.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class InertAnimation;
 
 class AnimationStack {
     DISALLOW_ALLOCATION();
     WTF_MAKE_NONCOPYABLE(AnimationStack);
 public:
     AnimationStack();
 
     void add(PassOwnPtrWillBeRawPtr<SampledEffect> effect) { m_effects.append(effect); }
     bool isEmpty() const { return m_effects.isEmpty(); }
     bool affects(CSSPropertyID) const;
     bool hasActiveAnimationsOnCompositor(CSSPropertyID) const;
-    static WillBeHeapHashMap<CSSPropertyID, RefPtrWillBeMember<Interpolation> > activeInterpolations(AnimationStack*, const WillBeHeapVector<RawPtrWillBeMember<InertAnimation> >* newAnimations, const WillBeHeapHashSet<RawPtrWillBeMember<const AnimationPlayer> >* suppressedAnimationPlayers, Animation::Priority, double timelineCurrentTime);
+    static InterpolationPipelineMap activeInterpolations(AnimationStack*, const WillBeHeapVector<RawPtrWillBeMember<InertAnimation>>* newAnimations, const WillBeHeapHashSet<RawPtrWillBeMember<const AnimationPlayer>>* suppressedAnimationPlayers, Animation::Priority, double timelineCurrentTime);
 
     bool getAnimatedBoundingBox(FloatBox&, CSSPropertyID) const;
     void trace(Visitor*);
 
 private:
     void simplifyEffects();
     // Effects sorted by priority. Lower priority at the start of the list.
-    WillBeHeapVector<OwnPtrWillBeMember<SampledEffect> > m_effects;
+    WillBeHeapVector<OwnPtrWillBeMember<SampledEffect>> m_effects;
 
     friend class AnimationAnimationStackTest;
 };
 
 } // namespace blink
 
 #endif // AnimationStack_h