Add helper for computing outset for 'outline'

Source/core/style/ComputedStyle.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 514 matching lines @@
     unsigned short outlineSize() const { return max(0, outlineWidth() + outlineOffset()); }
     unsigned short outlineWidth() const
     {
         if (m_background->outline().style() == BNONE)
             return 0;
         return m_background->outline().width();
     }
     bool hasOutline() const { return outlineWidth() > 0 && outlineStyle() > BHIDDEN; }
     EBorderStyle outlineStyle() const { return m_background->outline().style(); }
     OutlineIsAuto outlineStyleIsAuto() const { return static_cast<OutlineIsAuto>(m_background->outline().isAuto()); }
+    int outlineOutset() const;
 
     EOverflow overflowX() const { return static_cast<EOverflow>(noninherited_flags.overflowX); }
     EOverflow overflowY() const { return static_cast<EOverflow>(noninherited_flags.overflowY); }
     // It's sufficient to just check one direction, since it's illegal to have visible on only one overflow value.
     bool isOverflowVisible() const { ASSERT(overflowX() != OVISIBLE || overflowX() == overflowY()); return overflowX() == OVISIBLE; }
     bool isOverflowPaged() const { return overflowY() == OPAGEDX || overflowY() == OPAGEDY; }
 
     EVisibility visibility() const { return static_cast<EVisibility>(inherited_flags._visibility); }
     EVerticalAlign verticalAlign() const { return static_cast<EVerticalAlign>(noninherited_flags.verticalAlign); }
     const Length& verticalAlignLength() const { return m_box->verticalAlign(); }
@@ skipping 1356 matching lines @@
 }
 
 inline bool ComputedStyle::hasPseudoElementStyle() const
 {
     return noninherited_flags.pseudoBits & PSEUDO_ELEMENT_MASK;
 }
 
 } // namespace blink
 
 #endif // ComputedStyle_h