Better scrolling fix

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 241 matching lines @@
     {
         scrollToOffset(toDoubleSize(position), ScrollOffsetClamped, scrollBehavior, scrollType);
     }
 
     // Returns true if a layout object was marked for layout. In such a case, the layout scope's root
     // should be laid out again.
     bool updateAfterLayout(SubtreeLayoutScope* = nullptr);
     void updateAfterStyleChange(const ComputedStyle*);
     void updateAfterOverflowRecalc();
 
+    void clampPositionAfterLayout();
+
     bool updateAfterCompositingChange() override;
 
     bool hasScrollbar() const { return hasHorizontalScrollbar() || hasVerticalScrollbar(); }
     bool hasOverflowControls() const { return hasScrollbar() || scrollCorner() || resizer(); }
 
     LayoutScrollbarPart* scrollCorner() const override { return m_scrollCorner; }
 
     void resize(const PlatformEvent&, const LayoutSize&);
     IntSize offsetFromResizeCorner(const IntPoint& absolutePoint) const;
 
@@ skipping 154 matching lines @@
 #endif
 };
 
 DEFINE_TYPE_CASTS(PaintLayerScrollableArea, ScrollableArea, scrollableArea,
     scrollableArea->isPaintLayerScrollableArea(),
     scrollableArea.isPaintLayerScrollableArea());
 
 } // namespace blink
 
 #endif // LayerScrollableArea_h