Support Promise<T> syntax in the IDL parser.

tools/idl_parser/idl_lexer.py

 #!/usr/bin/env python
 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """ Lexer for PPAPI IDL
 
 The lexer uses the PLY library to build a tokenizer which understands both
 WebIDL and Pepper tokens.
 
@@ skipping 75 matching lines @@
     'inherit' : 'INHERIT',
     'interface' : 'INTERFACE',
     'legacycaller' : 'LEGACYCALLER',
     'long' : 'LONG',
     'Nan' : 'NAN',
     'null' : 'NULL',
     'object' : 'OBJECT',
     'octet' : 'OCTET',
     'optional' : 'OPTIONAL',
     'or' : 'OR',
-    'partial'  : 'PARTIAL',
+    'partial' : 'PARTIAL',
+    'Promise' : 'PROMISE',
     'readonly' : 'READONLY',
     'RegExp' : 'REGEXP',
     'sequence' : 'SEQUENCE',
     'serializer' : 'SERIALIZER',
     'setter': 'SETTER',
     'short' : 'SHORT',
     'static' : 'STATIC',
     'stringifier' : 'STRINGIFIER',
     'typedef' : 'TYPEDEF',
     'true' : 'TRUE',
@@ skipping 172 matching lines @@
     self.tokens = []
     self._AddTokens(IDLLexer.tokens)
     self._AddKeywords(IDLLexer.keywords)
     self._lexobj = None
     self.last = None
     self.lines = None
 
 # If run by itself, attempt to build the lexer
 if __name__ == '__main__':
   lexer_object = IDLLexer()