Revert 148647 "Remove frame flattening support as Chromium has n..."

trunk/Source/core/page/FrameView.h

Index: trunk/Source/core/page/FrameView.h
===================================================================
--- trunk/Source/core/page/FrameView.h	(revision 148648)
+++ trunk/Source/core/page/FrameView.h	(working copy)
@@ -91,6 +91,8 @@
 
     virtual PassRefPtr<Scrollbar> createScrollbar(ScrollbarOrientation);
 
+    virtual bool avoidScrollbarCreation() const;
+
     virtual void setContentsSize(const IntSize&);
 
     void layout(bool allowSubtree = true);
@@ -245,6 +247,8 @@
 
     Color documentBackgroundColor() const;
 
+    bool isInChildFrameWithFrameFlattening() const;
+
     static double currentPaintTimeStamp() { return sCurrentPaintTimeStamp; } // returns 0 if not painting
     
     void updateLayoutAndStyleIfNeededRecursive();
@@ -438,6 +442,8 @@
 
     FrameView* parentFrameView() const;
 
+    bool doLayoutWithFrameFlattening(bool allowSubtree);
+
     virtual AXObjectCache* axObjectCache() const;
     void notifyWidgetsInAllFrames(WidgetNotification);
     void removeFromAXObjectCache();