[Slimming paint] [New Multicolumn] Repaint column rules when they change.

Source/core/rendering/style/RenderStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. 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.
  *
@@ skipping 1491 matching lines @@
 {
     ASSERT(path);
     rareNonInheritedData.access()->m_transform.access()->m_motion.m_path = path;
 }
 
 void RenderStyle::resetMotionPath()
 {
     rareNonInheritedData.access()->m_transform.access()->m_motion.m_path = nullptr;
 }
 
+bool RenderStyle::columnRuleEquivalent(const RenderStyle* otherStyle) const
+{
+    return columnRuleStyle() == otherStyle->columnRuleStyle()
+        && columnRuleWidth() == otherStyle->columnRuleWidth()
+        && visitedDependentColor(CSSPropertyWebkitColumnRuleColor) == otherStyle->visitedDependentColor(CSSPropertyWebkitColumnRuleColor);
+}
+
 TextEmphasisMark RenderStyle::textEmphasisMark() const
 {
     TextEmphasisMark mark = static_cast<TextEmphasisMark>(rareInheritedData->textEmphasisMark);
     if (mark != TextEmphasisMarkAuto)
         return mark;
 
     if (isHorizontalWritingMode())
         return TextEmphasisMarkDot;
 
     return TextEmphasisMarkSesame;
@@ skipping 125 matching lines @@
         horizontal || includeLogicalRightEdge);
 
     edges[BSLeft] = BorderEdge(borderLeftWidth(),
         visitedDependentColor(CSSPropertyBorderLeftColor),
         borderLeftStyle(),
         borderLeftIsTransparent(),
         !horizontal || includeLogicalLeftEdge);
 }
 
 } // namespace blink