Make a '::distributed' pseudo element the first-ever client who can accept a relative selector.

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 2ec1ec9a5ad99f4bc5d8b1de0fc82ec39a75bef6..3609e15748bf844b40880d9c983389679abd0044 100644
--- a/Source/core/css/CSSSelector.h
+++ b/Source/core/css/CSSSelector.h
@@ -80,7 +80,8 @@ namespace WebCore {
             IndirectAdjacent,
             SubSelector,
             ShadowPseudo,
-            ShadowDistributed
+            ShadowVirtualDescendant,
+            ShadowVirtualChild

[dglazkov, 2013/05/22 17:43:43]

Introducing "virtual" here is bugging me. What does the word mean in this
context? I understand that you're aiming for a "virtual scoping root", but worry
that it isn't clear.

Another thought: isn't adding the "virtual" bit into Relation sort of
overloading it?

         };
 
         enum PseudoType {
@@ -340,7 +341,7 @@ inline bool CSSSelector::isDistributedPseudoElement() const
 
 inline bool CSSSelector::isShadowDistributed() const
 {
-    return m_relation == CSSSelector::ShadowDistributed;
+    return m_relation == CSSSelector::ShadowVirtualDescendant || m_relation == CSSSelector::ShadowVirtualChild;
 }
 
 inline void CSSSelector::setValue(const AtomicString& value)