Use the StyleResolverParentScope for ShadowRoot

Source/core/css/resolver/StyleResolverParentScope.h

Index: Source/core/css/resolver/StyleResolverParentScope.h
diff --git a/Source/core/css/resolver/StyleResolverParentScope.h b/Source/core/css/resolver/StyleResolverParentScope.h
index 58624fa2b83269747e2cdc72de92f9a1b22832ed..8972b42088bfcce55f34b329c772e4037348155a 100644
--- a/Source/core/css/resolver/StyleResolverParentScope.h
+++ b/Source/core/css/resolver/StyleResolverParentScope.h
@@ -7,13 +7,14 @@
 
 #include "core/css/resolver/StyleResolver.h"
 #include "core/dom/Element.h"
+#include "core/dom/shadow/ShadowRoot.h"
 
 namespace WebCore {
 
 // Maintains the parent element stack (and bloom filter) inside recalcStyle.
 class StyleResolverParentScope FINAL {
 public:
-    explicit StyleResolverParentScope(Element& parent);
+    explicit StyleResolverParentScope(Node& parent);
     ~StyleResolverParentScope();
 
     static void ensureParentStackIsPushed();
@@ -21,27 +22,34 @@ public:
 private:
     void pushParentIfNeeded();
 
-    Element& m_parent;
+    Node& m_parent;
     bool m_pushed;
     StyleResolverParentScope* m_previous;
+    StyleResolver& m_resolver;
 
     static StyleResolverParentScope* s_currentScope;
 };
 
-inline StyleResolverParentScope::StyleResolverParentScope(Element& parent)
+inline StyleResolverParentScope::StyleResolverParentScope(Node& parent)
     : m_parent(parent)
     , m_pushed(false)
     , m_previous(s_currentScope)
+    , m_resolver(*m_parent.document().styleResolver())
 {
     ASSERT(m_parent.document().inStyleRecalc());
+    ASSERT(parent.isElementNode() || parent.isShadowRoot());
     s_currentScope = this;
 }
 
 inline StyleResolverParentScope::~StyleResolverParentScope()
 {
-    if (m_pushed)
-        m_parent.document().styleResolver()->popParentElement(m_parent);
     s_currentScope = m_previous;
+    if (!m_pushed)
+        return;
+    if (m_parent.isElementNode())
+        m_resolver.popParentElement(toElement(m_parent));
+    else
+        m_resolver.popParentShadowRoot(toShadowRoot(m_parent));
 }
 
 inline void StyleResolverParentScope::ensureParentStackIsPushed()
@@ -56,7 +64,10 @@ inline void StyleResolverParentScope::pushParentIfNeeded()
         return;
     if (m_previous)
         m_previous->pushParentIfNeeded();
-    m_parent.document().styleResolver()->pushParentElement(m_parent);
+    if (m_parent.isElementNode())
+        m_resolver.pushParentElement(toElement(m_parent));
+    else
+        m_resolver.pushParentShadowRoot(toShadowRoot(m_parent));
     m_pushed = true;
 }