Make getComputedStyle optimization work for adjacent combinators.

Source/core/dom/ContainerNode.h

Index: Source/core/dom/ContainerNode.h
diff --git a/Source/core/dom/ContainerNode.h b/Source/core/dom/ContainerNode.h
index b883311724178a50c25cfdc1429627498a362f0e..1389bbec7af92eb1e41f8b7529746aec18ddaa63 100644
--- a/Source/core/dom/ContainerNode.h
+++ b/Source/core/dom/ContainerNode.h
@@ -155,6 +155,8 @@ public:
     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();
@@ -313,6 +315,13 @@ inline void ContainerNode::detachChildren(const AttachContext& context)
         child->detach(childrenContext);
 }
 
+inline bool ContainerNode::needsAdjacentStyleRecalc() const
+{
+    if (!childrenAffectedByDirectAdjacentRules() && !childrenAffectedByIndirectAdjacentRules())
+        return false;
+    return childNeedsStyleRecalc() || childNeedsStyleInvalidation();
+}
+
 inline unsigned Node::countChildren() const
 {
     if (!isContainerNode())