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

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index 5de0390a18066f89d4c6313834d575e3c1740414..aec54a7c7a30fc8c3a59783ff2bdffc3cd84f4df 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -349,7 +349,7 @@ ElementAnimations& Element::ensureElementAnimations()
 {
     ElementRareData& rareData = ensureElementRareData();
     if (!rareData.elementAnimations())
-        rareData.setElementAnimations(adoptPtrWillBeNoop(new ElementAnimations()));
+        rareData.setElementAnimations(new ElementAnimations);
     return *rareData.elementAnimations();
 }