Recalc sibling styles for forward positional rules on mutations only.

Source/core/dom/ElementRareData.h

 /*
  * Copyright (C) 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 David Smith <catfish.man@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
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 215 matching lines @@
 
 inline void ElementRareData::resetDynamicRestyleObservations()
 {
     clearFlag(ChildrenAffectedByFocus);
     clearFlag(ChildrenAffectedByHover);
     clearFlag(ChildrenAffectedByActive);
     clearFlag(ChildrenAffectedByDrag);
     clearFlag(ChildrenAffectedByFirstChildRules);
     clearFlag(ChildrenAffectedByLastChildRules);
     clearFlag(ChildrenAffectedByDirectAdjacentRules);
+    clearFlag(ChildrenAffectedByIndirectAdjacentRules);
     clearFlag(ChildrenAffectedByForwardPositionalRules);
     clearFlag(ChildrenAffectedByBackwardPositionalRules);
 }
 
 } // namespace
 
 #endif // ElementRareData_h