Implement ::shadow pseudo element and replace /shadow/ with ::shadow.

Source/core/css/CSSSelector.h

Index: Source/core/css/CSSSelector.h
diff --git a/Source/core/css/CSSSelector.h b/Source/core/css/CSSSelector.h
index 399b2ad3f90c0faed81ebdd1ad51aeb20a6ef624..00e155131e168b95429cb69e3e6a9498f1e83c57 100644
--- a/Source/core/css/CSSSelector.h
+++ b/Source/core/css/CSSSelector.h
@@ -128,11 +128,8 @@ namespace WebCore {
             DirectAdjacent, // + combinator
             IndirectAdjacent, // ~ combinator
             SubSelector, // "No space" combinator
-            ShadowPseudo, // Special case of shadow DOM pseudo elements
-            // FIXME: implement named combinator (i.e. named relation) and
-            // replace the following /shadow/ and /shadow-deep/ with the implementation.
-            Shadow, // /shadow/ combinator
-            ShadowDeep, // /shadow-deep/ combinator
+            ShadowPseudo, // Special case of shadow DOM pseudo elements / shadow pseudo element
+            ShadowDeep // /shadow-deep/ combinator
         };
 
         enum PseudoType {
@@ -217,7 +214,8 @@ namespace WebCore {
             PseudoUnresolved,
             PseudoContent,
             PseudoHost,
-            PseudoHostContext
+            PseudoHostContext,
+            PseudoShadow
         };
 
         enum MarginBoxType {
@@ -287,6 +285,7 @@ namespace WebCore {
         bool isSiblingSelector() const;
         bool isAttributeSelector() const;
         bool isContentPseudoElement() const;
+        bool isShadowPseudoElement() const;
         bool isHostPseudoClass() const;
 
         // FIXME: selectors with no tagHistory() get a relation() of Descendant. It should instead be
@@ -417,6 +416,11 @@ inline bool CSSSelector::isContentPseudoElement() const
     return m_match == PseudoElement && pseudoType() == PseudoContent;
 }
 
+inline bool CSSSelector::isShadowPseudoElement() const
+{
+    return m_match == PseudoElement && pseudoType() == PseudoShadow;
+}
+
 inline void CSSSelector::setValue(const AtomicString& value)
 {
     ASSERT(m_match != Tag);