[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 ddee2df92be60fbc5fc8bbdf42b2c34de427e6f0..28ab3ec4cb43de2186759ef606900addcfb39db6 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();
 }