Fix paint invalidation rect tracking within composited scrolling layers.

Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. 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 728 matching lines @@
     if (!hasOverflowClip())
         return false;
 
     bool hasScrollableOverflow = hasScrollableOverflowX() || hasScrollableOverflowY();
     if (scrollsOverflow() && hasScrollableOverflow)
         return true;
 
     return node && node->hasEditableStyle();
 }
 
-bool LayoutBox::usesCompositedScrolling() const
-{
-    return hasOverflowClip() && hasLayer() && layer()->scrollableArea()->usesCompositedScrolling();
-}
-
 void LayoutBox::autoscroll(const IntPoint& positionInRootFrame)
 {
     LocalFrame* frame = this->frame();
     if (!frame)
         return;
 
     FrameView* frameView = frame->view();
     if (!frameView)
         return;
 
@@ skipping 3978 matching lines @@
     StyleImage* borderImage = style()->borderImage().image();
     return borderImage && borderImage->canRender(*this, style()->effectiveZoom()) && borderImage->isLoaded();
 }
 
 ShapeOutsideInfo* LayoutBox::shapeOutsideInfo() const
 {
     return ShapeOutsideInfo::isEnabledFor(*this) ? ShapeOutsideInfo::info(*this) : nullptr;
 }
 
 } // namespace blink