Recalc sibling styles for forward positional rules on mutations only.

Source/core/css/SelectorChecker.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 275 matching lines @@
         nextContext.element = ElementTraversal::previousSibling(*context.element);
         if (!nextContext.element)
             return SelectorFailsAllSiblings;
         nextContext.isSubSelector = false;
         nextContext.elementStyle = 0;
         return match(nextContext, siblingTraversalStrategy, result);
 
     case CSSSelector::IndirectAdjacent:
         if (m_mode == ResolvingStyle) {
             if (Node* parent = context.element->parentElementOrShadowRoot())
-                SiblingRuleHelper(parent).setChildrenAffectedByForwardPositionalRules();
+                SiblingRuleHelper(parent).setChildrenAffectedByIndirectAdjacentRules();
         }
         nextContext.element = ElementTraversal::previousSibling(*context.element);
         nextContext.isSubSelector = false;
         nextContext.elementStyle = 0;
         for (; nextContext.element; nextContext.element = ElementTraversal::previousSibling(*nextContext.element)) {
             Match match = this->match(nextContext, siblingTraversalStrategy, result);
             if (match == SelectorMatches || match == SelectorFailsAllSiblings || match == SelectorFailsCompletely)
                 return match;
         };
         return SelectorFailsAllSiblings;
@@ skipping 794 matching lines @@
     return element.focused() && isFrameFocused(element);
 }
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const DOMSiblingTraversalStrategy&, MatchResult*) const;
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const ShadowDOMSiblingTraversalStrategy&, MatchResult*) const;
 
 }