Convert LayoutState/LayoutStateMaintainer/LayoutStateDisabler to references

Source/core/frame/FrameView.h

Index: Source/core/frame/FrameView.h
diff --git a/Source/core/frame/FrameView.h b/Source/core/frame/FrameView.h
index a83d2fac5cbf7c0f62110438ca780436ece97d9c..d9ec348f6839b15dceafc336eb5124caaf84457b 100644
--- a/Source/core/frame/FrameView.h
+++ b/Source/core/frame/FrameView.h
@@ -307,6 +307,7 @@ public:
     virtual void willRemoveScrollbar(Scrollbar*, ScrollbarOrientation) OVERRIDE;
 
     virtual bool shouldAttemptToScrollUsingFastPath() const OVERRIDE;
+    bool isSubtreeLayout() const { return !!m_layoutSubtreeRoot; }
 
 protected:
     virtual bool scrollContentsFastPath(const IntSize& scrollDelta, const IntRect& rectToScroll, const IntRect& clipRect) OVERRIDE;
@@ -397,7 +398,6 @@ private:
 
     void setLayoutSizeInternal(const IntSize&);
 
-    bool isSubtreeLayout() const { return !!m_layoutSubtreeRoot; }
     bool repaintAllowed() const
     {
         if (!RuntimeEnabledFeatures::repaintAfterLayoutEnabled())