[Oilpan]: Move CSSFontSelectorClient to the oilpan heap using transition types.

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 cf0229c9325faffb0842d5926766bdd8d56a4b13..0d07f2528d0d2d675e4e4a607481392466003c83 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -111,10 +111,11 @@ using namespace HTMLNames;
 using namespace XMLNames;
 
 class StyleResolverParentPusher {
+    STACK_ALLOCATED();
 public:
     explicit StyleResolverParentPusher(Element& parent)
         : m_parent(parent)
-        , m_pushedStyleResolver(0)
+        , m_pushedStyleResolver(nullptr)
     {
     }
     void push()
@@ -141,7 +142,7 @@ public:
 
 private:
     Element& m_parent;
-    StyleResolver* m_pushedStyleResolver;
+    RawPtrWillBeMember<StyleResolver> m_pushedStyleResolver;
 };
 
 typedef Vector<RefPtr<Attr> > AttrNodeList;