HTML parser: Add show/toString() debug helper methods

third_party/WebKit/Source/core/html/parser/HTMLToken.h

 /*
  * Copyright (C) 2013 Google, Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 482 matching lines @@
     bool m_selfClosing;
     AttributeList m_attributes;
 
     // A pointer into m_attributes used during lexing.
     Attribute* m_currentAttribute;
 
     // For DOCTYPE
     std::unique_ptr<DoctypeData> m_doctypeData;
 };
 
+#ifndef NDEBUG
+const char* toString(HTMLToken::TokenType);
+#endif
+
 } // namespace blink
 
 #endif