Implement ::placeholder CSS selector.

third_party/WebKit/Source/core/css/CSSSelector.h

 /*
  * Copyright (C) 1999-2003 Lars Knoll (knoll@kde.org)
  *               1999 Waldo Bastian (bastian@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2008, 2009, 2010, 2013 Apple Inc. All rights
  * reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 220 matching lines @@
   };
 
   PseudoType getPseudoType() const {
     return static_cast<PseudoType>(m_pseudoType);
   }
   void updatePseudoType(const AtomicString&, bool hasArguments);
 
   static PseudoType parsePseudoType(const AtomicString&, bool hasArguments);
   static PseudoId parsePseudoId(const String&);
   static PseudoId pseudoId(PseudoType);
+  static AtomicString aliasForShadowPseudoId(const AtomicString&);
 
   // Selectors are kept in an array by CSSSelectorList. The next component of
   // the selector is the next item in the array.
   const CSSSelector* tagHistory() const {
     return m_isLastInTagHistory ? 0 : const_cast<CSSSelector*>(this + 1);
   }
 
   const QualifiedName& tagQName() const;
   const AtomicString& value() const;
   const AtomicString& serializingValue() const;
@@ skipping 282 matching lines @@
 }
 
 inline bool CSSSelector::isIdClassOrAttributeSelector() const {
   return isAttributeSelector() || match() == CSSSelector::Id ||
          match() == CSSSelector::Class;
 }
 
 }  // namespace blink
 
 #endif  // CSSSelector_h