Fix fixed-background offset issue

Source/core/paint/PaintInfo.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google 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
@@ skipping 91 matching lines @@
     {
         if (rect != LayoutRect::infiniteIntRect())
             rect = localToParentTransform.inverse().mapRect(rect);
     }
 
     // FIXME: Introduce setters/getters at some point. Requires a lot of changes throughout layout/.
     GraphicsContext* context;
     IntRect rect; // dirty rect used for culling non-intersecting layoutObjects
     PaintPhase phase;
     LayoutObject* paintingRoot; // used to draw just one element and its visual kids
+    IntPoint accumulatedScrollOffsetSincePaintContainer;
 
 private:
     const LayoutBoxModelObject* m_paintContainer; // the box model object that originates the current painting
 
     const PaintLayerFlags m_paintFlags;
     const GlobalPaintFlags m_globalPaintFlags;
 };
 
 } // namespace blink
 
 #endif // PaintInfo_h