Ensure that if FrameView::isScrollable() is false, the assoc WebLayer is, too.

Source/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ skipping 152 matching lines @@
     virtual IntSize inputEventsOffsetForEmulation() const OVERRIDE;
     void setInputEventsTransformForEmulation(const IntSize&, float);
 
     virtual void setScrollPosition(const IntPoint&) OVERRIDE;
     virtual void repaintFixedElementsAfterScrolling();
     virtual void updateFixedElementsAfterScrolling();
     virtual bool shouldRubberBandInDirection(ScrollDirection) const;
     virtual bool isRubberBandInProgress() const OVERRIDE;
     void setScrollPositionNonProgrammatically(const IntPoint&);
 
+    bool hasOverflow() const;
+    bool isVisibleToHitTesting() const;
+
     // This is different than visibleContentRect() in that it ignores negative (or overly positive)
     // offsets from rubber-banding, and it takes zooming into account.
     LayoutRect viewportConstrainedVisibleContentRect() const;
 
     AtomicString mediaType() const;
     void setMediaType(const AtomicString&);
     void adjustMediaTypeForPrinting(bool printing);
 
     void setCannotBlitToWindow();
     void setIsOverlapped(bool);
@@ skipping 397 matching lines @@
     static const unsigned visualPixelThreshold = 32 * 32;
     if (m_visuallyNonEmptyPixelCount > visualPixelThreshold)
         setIsVisuallyNonEmpty();
 }
 
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 
 } // namespace WebCore
 
 #endif // FrameView_h