[Oilpan] Migrate most classes under core/animations to Oilpan heap.

Source/core/animation/animatable/AnimatableColor.h

Index: Source/core/animation/animatable/AnimatableColor.h
diff --git a/Source/core/animation/animatable/AnimatableColor.h b/Source/core/animation/animatable/AnimatableColor.h
index 4e0bde474239da0ba6daf9ad04373ef82ed3b5c3..df96d9237953dac2ced6afa576c26afe23bf436b 100644
--- a/Source/core/animation/animatable/AnimatableColor.h
+++ b/Source/core/animation/animatable/AnimatableColor.h
@@ -58,14 +58,14 @@ private:
 // but inefficient.
 class CORE_EXPORT AnimatableColor final : public AnimatableValue {
 public:
-    static PassRefPtrWillBeRawPtr<AnimatableColor> create(const AnimatableColorImpl&, const AnimatableColorImpl& visitedLinkColor);
+    static AnimatableColor* create(const AnimatableColorImpl&, const AnimatableColorImpl& visitedLinkColor);
     Color color() const { return m_color.toColor(); }
     Color visitedLinkColor() const { return m_visitedLinkColor.toColor(); }
 
     DEFINE_INLINE_VIRTUAL_TRACE() { AnimatableValue::trace(visitor); }
 
 protected:
-    virtual PassRefPtrWillBeRawPtr<AnimatableValue> interpolateTo(const AnimatableValue*, double fraction) const override;
+    virtual AnimatableValue* interpolateTo(const AnimatableValue*, double fraction) const override;
 
 private:
     AnimatableColor(const AnimatableColorImpl& color, const AnimatableColorImpl& visitedLinkColor)