Allow empty strings as enum values.

tools/dom/scripts/idlparser.py

 #!/usr/bin/python
 # Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 import re
 import subprocess
 import tempfile
 
 from pegparser import *
@@ skipping 56 matching lines @@
     def _Definition():
       return syntax_switch(
         # Web IDL:
         OR(Module, Interface, ExceptionDef, TypeDef, ImplStmt,
            ValueTypeDef, Const, Enum),
         # WebKit:
         OR(Module, Interface, Enum, TypeDef))
 
     def Enum():
       def StringLiteral():
-        return re.compile(r'"\w+"')
+        return re.compile(r'"\w*"')
 
       return ['enum', Id, '{', MAYBE(MANY(StringLiteral, ',')), '}', ';']
 
     def Module():
       return syntax_switch(
         # Web IDL:
         [MAYBE(ExtAttrs), 'module', Id, '{', _Definitions, '}',
          MAYBE(';')],
         # WebKit:
         ['module', MAYBE(ExtAttrs), Id, '{', _Definitions, '}',
@@ skipping 350 matching lines @@
     Args:
       content -- text to parse.
       defines -- an array of pre-processor defines.
       includePaths -- an array of path strings used by the
         gcc pre-processor.
     """
     if self._syntax == WEBKIT_SYNTAX:
       content = self._pre_process(content, defines, includePaths)
 
     return self._pegparser.parse(content)