Implement /content/ combinator.

Source/core/css/SelectorFilter.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 144 matching lines @@
                 // Disable fastRejectSelector.
                 *identifierHashes = 0;
                 return;
             }
             // Fall through.
         case CSSSelector::ShadowAll:
         case CSSSelector::ShadowDeep:
             skipOverSubselectors = false;
             collectDescendantSelectorIdentifierHashes(*current, hash);
             break;
+        case CSSSelector::ShadowContent:
+            // Disable fastRejectSelector.
+            *identifierHashes = 0;
+            return;
         }
         if (hash == end)
             return;
         relation = current->relation();
         relationIsAffectedByPseudoContent = current->relationIsAffectedByPseudoContent();
     }
     *hash = 0;
 }
 
 }