Oilpan: Move CSSStyleDeclaration and subclasses to the heap using transistion types.

Source/core/dom/ElementRareData.cpp

Index: Source/core/dom/ElementRareData.cpp
diff --git a/Source/core/dom/ElementRareData.cpp b/Source/core/dom/ElementRareData.cpp
index f87ff4227d432d96e6c8f492c834a673df8292b9..4511bed0332dd68090c9b9c19cbd5a85e379c99b 100644
--- a/Source/core/dom/ElementRareData.cpp
+++ b/Source/core/dom/ElementRareData.cpp
@@ -40,13 +40,14 @@ struct SameSizeAsElementRareData : NodeRareData {
     unsigned bitfields;
     LayoutSize sizeForResizing;
     IntSize scrollOffset;
-    void* pointers[12];
+    void* pointers[11];
+    OwnPtrWillBePersistent<InlineCSSStyleDeclaration> cssomWrapper;

[haraken, 2014/03/20 11:22:38]

Increasing the size of ElementRareData is sad. We might need to address this
increase when enabling the oilpan flag for the CSS hierarchy.

[wibling-chromium, 2014/03/20 11:59:33]

Yes, thankfully this should be larger while it is a persistent. Once we change
it to OwnPtrWillBeMember the size should be the same even with oilpan enabled.

 };
 
 CSSStyleDeclaration& ElementRareData::ensureInlineCSSStyleDeclaration(Element* ownerElement)
 {
     if (!m_cssomWrapper)
-        m_cssomWrapper = adoptPtr(new InlineCSSStyleDeclaration(ownerElement));
+        m_cssomWrapper = adoptPtrWillBeNoop(new InlineCSSStyleDeclaration(ownerElement));
     return *m_cssomWrapper;
 }