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

Source/core/animation/animatable/AnimatableValue.cpp

Index: Source/core/animation/animatable/AnimatableValue.cpp
diff --git a/Source/core/animation/animatable/AnimatableValue.cpp b/Source/core/animation/animatable/AnimatableValue.cpp
index 5a7666886a34caf128b3d6d16321d4435d1e486b..8fcb5ca97589cdd0d2ec97d89c6c27822c0ec809 100644
--- a/Source/core/animation/animatable/AnimatableValue.cpp
+++ b/Source/core/animation/animatable/AnimatableValue.cpp
@@ -39,11 +39,11 @@ namespace blink {
 
 const AnimatableValue* AnimatableValue::neutralValue()
 {
-    DEFINE_STATIC_REF_WILL_BE_PERSISTENT(AnimatableNeutral, neutralSentinelValue, (AnimatableNeutral::create()));
+    static AnimatableNeutral* neutralSentinelValue = (new Persistent<AnimatableNeutral>(AnimatableNeutral::create()))->get();
     return neutralSentinelValue;
 }
 
-PassRefPtrWillBeRawPtr<AnimatableValue> AnimatableValue::interpolate(const AnimatableValue* left, const AnimatableValue* right, double fraction)
+AnimatableValue* AnimatableValue::interpolate(const AnimatableValue* left, const AnimatableValue* right, double fraction)
 {
     ASSERT(left);
     ASSERT(right);