Don't always fully repaint on viewport resize

Source/core/rendering/style/RenderStyle.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * 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
@@ skipping 387 matching lines @@
     bool isFloating() const { return noninherited_flags._floating != NoFloat; }
     bool hasMargin() const { return surround->margin.nonZero(); }
     bool hasBorder() const { return surround->border.hasBorder(); }
     bool hasPadding() const { return surround->padding.nonZero(); }
     bool hasOffset() const { return surround->offset.nonZero(); }
     bool hasMarginBeforeQuirk() const { return marginBefore().quirk(); }
     bool hasMarginAfterQuirk() const { return marginAfter().quirk(); }
 
     bool hasBackgroundImage() const { return m_background->background().hasImage(); }
     bool hasFixedBackgroundImage() const { return m_background->background().hasFixedImage(); }
+    bool backgroundImageNeedsFullRepaintOnContainerWidthChange() const { return m_background->background().needsFullRepaintOnContainerWidthChange(); }
+    bool backgroundImageNeedsFullRepaintOnContainerHeightChange() const { return m_background->background().needsFullRepaintOnContainerHeightChange(); }
 
     bool hasEntirelyFixedBackground() const;
 
     bool hasAppearance() const { return appearance() != NoControlPart; }
 
     bool hasBackground() const
     {
         Color color = visitedDependentColor(CSSPropertyBackgroundColor);
         if (color.alpha())
             return true;
@@ skipping 1459 matching lines @@
 inline bool RenderStyle::hasPseudoElementStyle() const
 {
     return noninherited_flags._pseudoBits & PSEUDO_ELEMENT_MASK;
 }
 
 float calcBorderRadiiConstraintScaleFor(const FloatRect&, const FloatRoundedRect::Radii&);
 
 } // namespace WebCore
 
 #endif // RenderStyle_h