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

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 57710a6e8c1068b53c60e5418ded5876f1e418aa..1243c43dcbc5677b2f6ddc11642c27c7afcdd2fb 100644
--- a/Source/core/frame/FrameView.h
+++ b/Source/core/frame/FrameView.h
@@ -170,6 +170,9 @@ public:
     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;