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 02b5ef780e77abab724e690ba8da10d86669dae1..985a67b013956848aa1c5624613260bbdb9f81bf 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -1757,8 +1757,10 @@ void Document::recalcStyle(StyleChange 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();
@@ -2006,6 +2008,8 @@ void Document::detach(const AttachContext& context)
 
     unscheduleStyleRecalc();
 
+    clearStyleResolver();
+
     if (render)
         render->destroy();