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

Source/core/css/CSSSelector.cpp

 /*
  * Copyright (C) 1999-2003 Lars Knoll (knoll@kde.org)
  *               1999 Waldo Bastian (bastian@kde.org)
  *               2001 Andreas Schlapbach (schlpbch@iam.unibe.ch)
  *               2001-2003 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2002, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 666 matching lines @@
             }
         }
         if (cs->relation() != CSSSelector::SubSelector || !cs->tagHistory())
             break;
         cs = cs->tagHistory();
     }
 
     if (const CSSSelector* tagHistory = cs->tagHistory()) {
         switch (cs->relation()) {
         case CSSSelector::Descendant:
+            if (cs->relationIsForShadowDistributed())
+                return tagHistory->selectorText("::-webkit-distributed(" + str.toString() + rightSide + ")");
             return tagHistory->selectorText(" " + str.toString() + rightSide);
         case CSSSelector::Child:
+            if (cs->relationIsForShadowDistributed())
+                return tagHistory->selectorText("::-webkit-distributed(> " + str.toString() + rightSide + ")");
             return tagHistory->selectorText(" > " + str.toString() + rightSide);
         case CSSSelector::DirectAdjacent:
             return tagHistory->selectorText(" + " + str.toString() + rightSide);
         case CSSSelector::IndirectAdjacent:
             return tagHistory->selectorText(" ~ " + str.toString() + rightSide);
         case CSSSelector::SubSelector:
             ASSERT_NOT_REACHED();
         case CSSSelector::ShadowPseudo:
             return tagHistory->selectorText(str.toString() + rightSide);
-        case CSSSelector::ShadowDistributed:
-            return tagHistory->selectorText("::-webkit-distributed(" + str.toString() + rightSide + ")");
         }
     }
     return str.toString() + rightSide;
 }
 
 void CSSSelector::setAttribute(const QualifiedName& value)
 {
     createRareData();
     m_data.m_rareData->m_attribute = value;
 }
@@ skipping 94 matching lines @@
             return false;
         return (count - m_b) % m_a == 0;
     } else {
         if (count > m_b)
             return false;
         return (m_b - count) % (-m_a) == 0;
     }
 }
 
 } // namespace WebCore