Oilpan: Move AnimatableValue's hierarchy to oilpan's heap

Source/core/animation/AnimatableVisibility.cpp

Index: Source/core/animation/AnimatableVisibility.cpp
diff --git a/Source/core/animation/AnimatableVisibility.cpp b/Source/core/animation/AnimatableVisibility.cpp
index 8727081f9f646642e630b1c835f9aa8112b3a67a..dd3e48e5363c61ea3813e68fac03b1d16ae7883b 100644
--- a/Source/core/animation/AnimatableVisibility.cpp
+++ b/Source/core/animation/AnimatableVisibility.cpp
@@ -40,7 +40,7 @@ bool AnimatableVisibility::usesDefaultInterpolationWith(const AnimatableValue* v
     return from != VISIBLE && to != VISIBLE;
 }
 
-PassRefPtr<AnimatableValue> AnimatableVisibility::interpolateTo(const AnimatableValue* value, double fraction) const
+PassRefPtrWillBeRawPtr<AnimatableValue> AnimatableVisibility::interpolateTo(const AnimatableValue* value, double fraction) const
 {
     EVisibility from = m_visibility;
     EVisibility to = toAnimatableVisibility(value)->m_visibility;
@@ -58,4 +58,9 @@ bool AnimatableVisibility::equalTo(const AnimatableValue* value) const
     return m_visibility == toAnimatableVisibility(value)->m_visibility;
 }
 
+void AnimatableVisibility::trace(Visitor* visitor)
+{
+    AnimatableValue::trace(visitor);
+}
+
 } // namespace WebCore