Make getComputedStyle optimization work for adjacent combinators.

Source/core/dom/ContainerNode.h

 /*
  * 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, 2009, 2010, 2011, 2013 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.
@@ skipping 137 matching lines @@
 
     bool childrenAffectedByBackwardPositionalRules() const { return hasRestyleFlag(ChildrenAffectedByBackwardPositionalRules); }
     void setChildrenAffectedByBackwardPositionalRules() { setRestyleFlag(ChildrenAffectedByBackwardPositionalRules); }
 
     bool affectedByFirstChildRules() const { return hasRestyleFlag(AffectedByFirstChildRules); }
     void setAffectedByFirstChildRules() { setRestyleFlag(AffectedByFirstChildRules); }
 
     bool affectedByLastChildRules() const { return hasRestyleFlag(AffectedByLastChildRules); }
     void setAffectedByLastChildRules() { setRestyleFlag(AffectedByLastChildRules); }
 
+    bool needsAdjacentStyleRecalc() const;
+
     // FIXME: These methods should all be renamed to something better than "check",
     // since it's not clear that they alter the style bits of siblings and children.
     void checkForChildrenAdjacentRuleChanges();
     enum SiblingCheckType { FinishedParsingChildren, SiblingElementInserted, SiblingElementRemoved };
     void checkForSiblingStyleChanges(SiblingCheckType, Node* nodeBeforeChange, Node* nodeAfterChange);
     void recalcChildStyle(StyleRecalcChange);
 
     bool childrenSupportStyleSharing() const { return !hasRestyleFlags(); }
 
     // -----------------------------------------------------------------------------
@@ skipping 138 matching lines @@
 
 inline void ContainerNode::detachChildren(const AttachContext& context)
 {
     AttachContext childrenContext(context);
     childrenContext.resolvedStyle = nullptr;
 
     for (Node* child = firstChild(); child; child = child->nextSibling())
         child->detach(childrenContext);
 }
 
+inline bool ContainerNode::needsAdjacentStyleRecalc() const
+{
+    if (!childrenAffectedByDirectAdjacentRules() && !childrenAffectedByIndirectAdjacentRules())
+        return false;
+    return childNeedsStyleRecalc() || childNeedsStyleInvalidation();
+}
+
 inline unsigned Node::countChildren() const
 {
     if (!isContainerNode())
         return 0;
     return toContainerNode(this)->countChildren();
 }
 
 inline Node* Node::firstChild() const
 {
     if (!isContainerNode())
@@ skipping 28 matching lines @@
 inline void getChildNodes(ContainerNode& node, NodeVector& nodes)
 {
     ASSERT(!nodes.size());
     for (Node* child = node.firstChild(); child; child = child->nextSibling())
         nodes.append(child);
 }
 
 } // namespace blink
 
 #endif // ContainerNode_h