Fix several corner case issues of scrollbar paint invalidation

third_party/WebKit/Source/core/layout/LayoutBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 828 matching lines @@
             removeFloatingOrPositionedChildFromBlockLists();
     }
 
     void setIntrinsicContentLogicalHeight(LayoutUnit intrinsicContentLogicalHeight) const { m_intrinsicContentLogicalHeight = intrinsicContentLogicalHeight; }
 
     bool canRenderBorderImage() const;
 
     void mapLocalToContainer(const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = nullptr, const PaintInvalidationState* = nullptr) const override;
     void mapAbsoluteToLocalPoint(MapCoordinatesFlags, TransformState&) const override;
 
+    void clearPreviousPaintInvalidationRects() override;
+
 protected:
     void willBeDestroyed() override;
 
     void styleWillChange(StyleDifference, const ComputedStyle& newStyle) override;
     void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override;
     void updateFromStyle() override;
 
     // Returns false if it could not cheaply compute the extent (e.g. fixed background), in which case the returned rect may be incorrect.
     // FIXME: make this a const method once the LayoutBox reference in BoxPainter is const.
     bool getBackgroundPaintedExtent(LayoutRect&) const;
@@ skipping 200 matching lines @@
         if (UNLIKELY(inlineBoxWrapper() != nullptr))
             deleteLineBoxWrapper();
     }
 
     ensureRareData().m_inlineBoxWrapper = boxWrapper;
 }
 
 } // namespace blink
 
 #endif // LayoutBox_h