Replace RenderArena with PartitionAlloc.

Source/core/dom/Document.h

Index: Source/core/dom/Document.h
diff --git a/Source/core/dom/Document.h b/Source/core/dom/Document.h
index 8c285058fab386c307999943c953b95785e3cc1d..fc1b156eeac5a8f04ffe006332f49a5b5f30664e 100644
--- a/Source/core/dom/Document.h
+++ b/Source/core/dom/Document.h
@@ -132,7 +132,6 @@ class Prerenderer;
 class ProcessingInstruction;
 class Range;
 class RegisteredEventListener;
-class RenderArena;
 class RenderView;
 class RequestAnimationFrameCallback;
 class SVGDocumentExtensions;
@@ -508,8 +507,6 @@ public:
     virtual void suspendActiveDOMObjects(ActiveDOMObject::ReasonForSuspension) OVERRIDE;
     virtual void resumeActiveDOMObjects() OVERRIDE;
 
-    RenderArena* renderArena() { return m_renderArena.get(); }
-
     // Implemented in RenderView.h to avoid a cyclic header dependency this just
     // returns renderer so callers can avoid verbose casts.
     RenderView* renderView() const;
@@ -1264,8 +1261,6 @@ private:
     bool m_titleSetExplicitly;
     RefPtr<Element> m_titleElement;
 
-    RefPtr<RenderArena> m_renderArena;
-
     OwnPtr<AXObjectCache> m_axObjectCache;
     OwnPtr<DocumentMarkerController> m_markers;