Implement ::content

Source/core/css/CSSGrammar.y.in

 /*
  *  Copyright (C) 2002-2003 Lars Knoll (knoll@kde.org)
  *  Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  *  Copyright (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *  Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  *  Copyright (C) 2012 Intel Corporation. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
  *  License as published by the Free Software Foundation; either
@@ skipping 1165 matching lines @@
 selector:
     simple_selector
     | selector WHITESPACE
     | selector WHITESPACE simple_selector
     {
         $$ = $3;
         CSSParserSelector* end = $$;
         while (end->tagHistory())
             end = end->tagHistory();
         end->setRelation(CSSSelector::Descendant);
+        if ($1->isContentPseudoElement())
+            end->setRelationIsForShadowDistributed();
         end->setTagHistory(parser->sinkFloatingSelector($1));
     }
     | selector combinator simple_selector {
         $$ = $3;
         CSSParserSelector* end = $$;
         while (end->tagHistory())
             end = end->tagHistory();
         end->setRelation($2);
+        if ($1->isContentPseudoElement())
+            end->setRelationIsForShadowDistributed();
         end->setTagHistory(parser->sinkFloatingSelector($1));
     }
     ;
 
 namespace_selector:
     /* empty */ '|' { $$.clear(); }
     | '*' '|' { static LChar star = '*'; $$.init(&star, 1); }
     | IDENT '|'
     ;
 
@@ skipping 658 matching lines @@
 
 rule_error_recovery:
     /* empty */
   | rule_error_recovery error
   | rule_error_recovery invalid_square_brackets_block
   | rule_error_recovery invalid_parentheses_block
     ;
 
 %%