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

Source/core/animation/ElementAnimations.h

Index: Source/core/animation/ElementAnimations.h
diff --git a/Source/core/animation/ElementAnimations.h b/Source/core/animation/ElementAnimations.h
index 3bba2a443fdb72d8cfd1860c72673860433e2d93..29015a31cf7e9bbce77ed566e7ee7b2bb03f1b88 100644
--- a/Source/core/animation/ElementAnimations.h
+++ b/Source/core/animation/ElementAnimations.h
@@ -44,7 +44,7 @@ class CSSAnimations;
 
 using AnimationPlayerCountedSet = WillBeHeapHashCountedSet<RawPtrWillBeWeakMember<AnimationPlayer>>;
 
-class ElementAnimations : public NoBaseWillBeGarbageCollectedFinalized<ElementAnimations> {
+class ElementAnimations : public GarbageCollectedFinalized<ElementAnimations> {
     WTF_MAKE_NONCOPYABLE(ElementAnimations);
 public:
     ElementAnimations();
@@ -74,11 +74,6 @@ public:
     void updateBaseComputedStyle(const ComputedStyle*);
     void clearBaseComputedStyle();
 
-#if !ENABLE(OILPAN)
-    void addAnimation(Animation* animation) { m_animations.append(animation); }
-    void notifyAnimationDestroyed(Animation* animation) { m_animations.remove(m_animations.find(animation)); }
-#endif
-
     DECLARE_TRACE();
 
 private:
@@ -90,12 +85,6 @@ private:
     bool m_animationStyleChange;
     RefPtr<ComputedStyle> m_baseComputedStyle;
 
-#if !ENABLE(OILPAN)
-    // FIXME: Oilpan: This is to avoid a reference cycle that keeps Elements alive
-    // and won't be needed once the Node hierarchy becomes traceable.
-    Vector<Animation*> m_animations;
-#endif
-
     // CSSAnimations and DeferredLegacyStyleInterpolation checks if a style change is due to animation.
     friend class CSSAnimations;
     friend class DeferredLegacyStyleInterpolation;