ScopedStyleResolver should be cleared when ShadowRoot is removed from document.

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 cdb307c31809a4780d51822e552546e10b21e54f..0254d133c28f7bda090ec07fae5392c9758ec41e 100644
--- a/Source/core/css/resolver/StyleResolver.cpp
+++ b/Source/core/css/resolver/StyleResolver.cpp
@@ -254,13 +254,14 @@ void StyleResolver::processScopedRules(const RuleSet& authorRules, CSSStyleSheet
 
 void StyleResolver::resetAuthorStyle(TreeScope& treeScope)
 {
+    m_treeBoundaryCrossingRules.reset(&treeScope.rootNode());
+    resetRuleFeatures();
+
     ScopedStyleResolver* resolver = treeScope.scopedStyleResolver();
     if (!resolver)
         return;
 
-    m_treeBoundaryCrossingRules.reset(&treeScope.rootNode());
     resolver->resetAuthorStyle();
-    resetRuleFeatures();
     if (treeScope.rootNode().isDocumentNode())
         return;