Support 'paint-order' from SVG2.

Source/core/rendering/style/SVGRenderStyle.cpp

 /*
     Copyright (C) 2004, 2005, 2007 Nikolas Zimmermann <zimmermann@kde.org>
                   2004, 2005, 2010 Rob Buis <buis@kde.org>
     Copyright (C) Research In Motion Limited 2010. All rights reserved.
 
     Based on khtml code by:
     Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
     Copyright (C) 1999-2003 Lars Knoll (knoll@kde.org)
     Copyright (C) 2002-2003 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Apple Computer, Inc.
@@ skipping 209 matching lines @@
 
     if (svg_noninherited_flags.f.bufferedRendering != other->svg_noninherited_flags.f.bufferedRendering)
         return StyleDifferenceRepaint;
 
     if (svg_noninherited_flags.f.maskType != other->svg_noninherited_flags.f.maskType)
         return StyleDifferenceRepaint;
 
     return StyleDifferenceEqual;
 }
 
+EPaintOrderType SVGRenderStyle::paintOrderType(unsigned index) const
+{
+    ASSERT(index < 3);

[pdr., 2013/06/25 15:30:45]

Can you turn this 3 into a constant? I worry that we'll forget what it's for in
a years time.

+    unsigned pt = (paintOrder() >> (kPaintOrderBitwidth*index)) & ((1u << kPaintOrderBitwidth) - 1);
+    return (EPaintOrderType)pt;
 }
+
+}