Replace style sharing cousin list search with LRU

Source/core/css/resolver/StyleResolver.cpp

Index: Source/core/css/resolver/StyleResolver.cpp
diff --git a/Source/core/css/resolver/StyleResolver.cpp b/Source/core/css/resolver/StyleResolver.cpp
index 0341b1eedf196c5b80a67577b2bcaad7176b61c9..0dd3b83fdbfa71bb26faac6cc44fa308e64b8b09 100644
--- a/Source/core/css/resolver/StyleResolver.cpp
+++ b/Source/core/css/resolver/StyleResolver.cpp
@@ -243,6 +243,18 @@ void StyleResolver::collectFeatures()
     m_uncommonAttributeRuleSet = makeRuleSet(m_features.uncommonAttributeRules);
 }
 
+void StyleResolver::addToStyleSharingList(Element* element)
+{
+    if (m_styleSharingList.size() >= styleSharingListSize)
+        m_styleSharingList.remove(--m_styleSharingList.end());
+    m_styleSharingList.prepend(element);
+}
+
+void StyleResolver::clearStyleSharingList()
+{
+    m_styleSharingList.clear();
+}
+
 void StyleResolver::pushParentElement(Element* parent)
 {
     ASSERT(parent);