Replace style sharing cousin list search with LRU

Source/core/dom/ContainerNode.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "config.h"
 #include "core/dom/ContainerNode.h"
 
 #include "bindings/v8/ExceptionState.h"
 #include "bindings/v8/ExceptionStatePlaceholder.h"
+#include "core/css/resolver/StyleResolver.h"
 #include "core/dom/ChildListMutationScope.h"
 #include "core/dom/ContainerNodeAlgorithms.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/EventNames.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/FullscreenElementStack.h"
 #include "core/dom/MutationEvent.h"
 #include "core/dom/NodeRareData.h"
 #include "core/dom/NodeRenderStyle.h"
 #include "core/dom/NodeTraversal.h"
@@ skipping 27 matching lines @@
 
 static inline void attachAfterInsertion(Node* node, AttachBehavior attachBehavior = AttachLazily)
 {
     if (node->attached() || !node->parentNode() || !node->parentNode()->attached())
         return;
 
     if (attachBehavior == AttachLazily)
         node->lazyAttach();
     else
         node->attach();
+
+    if (StyleResolver* resolver = node->document().styleResolverIfExists())
+        resolver->clearStyleSharingList();
 }
 
 static void collectChildrenAndRemoveFromOldParent(Node* node, NodeVector& nodes, ExceptionState& es)
 {
     if (node->nodeType() != Node::DOCUMENT_FRAGMENT_NODE) {
         nodes.append(node);
         if (ContainerNode* oldParent = node->parentNode())
             oldParent->removeChild(node, es);
         return;
     }
@@ skipping 971 matching lines @@
         return true;
 
     if (node->isElementNode() && toElement(node)->shadow())
         return true;
 
     return false;
 }
 #endif
 
 } // namespace WebCore