Replace style sharing cousin list search with LRU

Source/core/testing/Internals.cpp

Index: Source/core/testing/Internals.cpp
diff --git a/Source/core/testing/Internals.cpp b/Source/core/testing/Internals.cpp
index 173c7f419de50af69ed449d0ffaf47209cec983a..ad961fa8d953f8c7873be042652f90b0bd0faed0 100644
--- a/Source/core/testing/Internals.cpp
+++ b/Source/core/testing/Internals.cpp
@@ -1544,11 +1544,17 @@ void Internals::toggleOverwriteModeEnabled(Document* document, ExceptionState&)
 
 unsigned Internals::numberOfLiveNodes() const
 {
+    if (StyleResolver* resolver = contextDocument()->styleResolverIfExists())
+        resolver->clearStyleSharingList();
+
     return InspectorCounters::counterValue(InspectorCounters::NodeCounter);
 }
 
 unsigned Internals::numberOfLiveDocuments() const
 {
+    if (StyleResolver* resolver = contextDocument()->styleResolverIfExists())
+        resolver->clearStyleSharingList();
+
     return InspectorCounters::counterValue(InspectorCounters::DocumentCounter);
 }
 
@@ -1841,6 +1847,11 @@ void Internals::garbageCollectDocumentResources(Document* document, ExceptionSta
         return;
     }
 
+    if (StyleResolver* resolver = contextDocument()->styleResolverIfExists())
+        resolver->clearStyleSharingList();
+    if (StyleResolver* resolver = document->styleResolverIfExists())
+        resolver->clearStyleSharingList();
+
     ResourceFetcher* fetcher = document->fetcher();
     if (!fetcher)
         return;