Add infrastructure for partial layouts

Source/core/rendering/RenderWidget.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2009, 2010 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 56 matching lines @@
     IntRect windowClipRect() const;
 
     void setIsOverlapped(bool);
 
     void ref() { ++m_refCount; }
     void deref();
 
 protected:
     RenderWidget(Element*);
 
-    FrameView* frameView() const { return m_frameView; }
+    FrameView* frameView() const OVERRIDE { return m_frameView; }

[esprehn, 2013/08/23 20:47:27]

Same deal, lets just use the one on RenderObject. Also these are missing the
virtual keyword.

[pdr., 2013/08/26 05:50:40]

We can't remove this function in favor of RenderObject's because the widget tree
can outlast the document, causing a crash when using document().
fast/block/child-not-removed-from-parent-lineboxes-crash.html tests this. I've
removed the OVERRIDE that was incorrectly put here.

 
     void clearWidget();
 
     virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle) OVERRIDE FINAL;
     virtual void layout();
     virtual void paint(PaintInfo&, const LayoutPoint&);
     virtual CursorDirective getCursor(const LayoutPoint&, Cursor&) const;
     virtual bool nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction) OVERRIDE;
 
     virtual void paintContents(PaintInfo&, const LayoutPoint&);
@@ skipping 24 matching lines @@
     ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isWidget());
     return static_cast<const RenderWidget*>(object);
 }
 
 // This will catch anyone doing an unnecessary cast.
 void toRenderWidget(const RenderWidget*);
 
 } // namespace WebCore
 
 #endif // RenderWidget_h