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

Source/core/animation/DeferredLegacyStyleInterpolation.cpp

Index: Source/core/animation/DeferredLegacyStyleInterpolation.cpp
diff --git a/Source/core/animation/DeferredLegacyStyleInterpolation.cpp b/Source/core/animation/DeferredLegacyStyleInterpolation.cpp
index b3b39ba2a6f3aa5e205128cdc869b8f7f8e09450..3eca9b77df8fb94baf6d98940b4b200f3a43b8a9 100644
--- a/Source/core/animation/DeferredLegacyStyleInterpolation.cpp
+++ b/Source/core/animation/DeferredLegacyStyleInterpolation.cpp
@@ -23,8 +23,8 @@ namespace blink {
 void DeferredLegacyStyleInterpolation::apply(StyleResolverState& state) const
 {
     if (m_outdated || !state.element()->elementAnimations() || !state.element()->elementAnimations()->isAnimationStyleChange()) {
-        RefPtrWillBeRawPtr<AnimatableValue> startAnimatableValue;
-        RefPtrWillBeRawPtr<AnimatableValue> endAnimatableValue;
+        AnimatableValue* startAnimatableValue;
+        AnimatableValue* endAnimatableValue;
 
         // Snapshot underlying values for neutral keyframes first because non-neutral keyframes will mutate the StyleResolverState.
         if (!m_endCSSValue) {