Arity indexing in dart:blink entry points

tools/dom/scripts/systemhtml.py

 #!/usr/bin/python
 # Copyright (c) 2012, 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.
 
 """This module provides shared functionality for the system to generate
 Dart:html APIs from the IDL database."""
 
 import emitter
 import logging
@@ skipping 1067 matching lines @@
         self._Metadata(info.type_name, info.declared_name, return_type),
         'static ' if info.IsStatic() else '',
         return_type,
         html_name,
         info.ParametersAsDeclaration(InputType))
     self._GenerateDispatcherBody(
         info,
         operations,
         declaration,
         GenerateCall,
-        lambda _, argument: IsOptional(argument),
+        IsOptional,
         can_omit_type_check=lambda type, pos: type == parameter_types[pos])
 
   def _AddInterfaceOperation(self, info, html_name):
     self._members_emitter.Emit(
         '\n'
         '  $TYPE $NAME($PARAMS);\n',
         TYPE=self.SecureOutputType(info.type_name, False, True),
         NAME=html_name,
         PARAMS=info.ParametersAsDeclaration(self._NarrowInputType))
 
@@ skipping 170 matching lines @@
 
   def AddFile(self, basename, library_name, path):
     self._libraries[library_name].AddFile(path)
 
   def AddTypeEntry(self, library_name, idl_name, dart_name):
     self._libraries[library_name].AddTypeEntry(idl_name, dart_name)
 
   def Emit(self, emitter, auxiliary_dir):
     for lib in self._libraries.values():
       lib.Emit(emitter, auxiliary_dir)