Replace style sharing cousin list search with LRU

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index 8c02630fe8c5c6f687b1d498b3a6b8f8956333e7..d422652307a099ba1e490012fd4a7b52a1ca5180 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -1514,6 +1514,9 @@ bool Element::recalcStyle(StyleChange change)
             change = Force;
         else if (change != Force)
             change = localChange;
+    } else {
+        // We still want to seed the style sharing list when just walking the tree to maximize sharing.
+        document()->styleResolver()->addToStyleSharingList(this);
     }
     StyleResolverParentPusher parentPusher(this);
 
@@ -1558,6 +1561,8 @@ bool Element::recalcStyle(StyleChange change)
             if (shouldRecalcStyle(change, element)) {
                 parentPusher.push();
                 didReattach = element->recalcStyle(change);
+            } else {
+                document()->styleResolver()->addToStyleSharingList(element);
             }
         }