Replace style sharing cousin list search with LRU

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 6a667cfd1a5a36dd378835223417c4b711400472..d04d081bd0a333ae5e0f42b780c3d6e1690a54c7 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -1767,8 +1767,10 @@ void Document::recalcStyle(StyleRecalcChange change)
         m_inStyleRecalc = false;
 
         // Pseudo element removal and similar may only work with these flags still set. Reset them after the style recalc.
-        if (m_styleResolver)
+        if (m_styleResolver) {
             m_styleSheetCollections->resetCSSFeatureFlags(m_styleResolver->ruleFeatureSet());
+            m_styleResolver->clearStyleSharingList();
+        }
 
         if (frameView) {
             frameView->resumeScheduledEvents();
@@ -2054,6 +2056,8 @@ void Document::detach(const AttachContext& context)
 
     unscheduleStyleRecalc();
 
+    clearStyleResolver();
+
     if (render)
         render->destroy();