Force named arguments in constructors.

lib/html/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 os
@@ skipping 66 matching lines @@
   def ConstructorInfo(self, interface_name):
     info = OperationInfo()
     info.overloads = None
     info.declared_name = interface_name
     info.name = interface_name
     info.constructor_name = self.name
     info.js_name = None
     info.type_name = interface_name
     info.param_infos = map(lambda tXn: ParamInfo(tXn[1], tXn[0], True),
                            self.opt_params)
+    info.requires_named_arguments = True
     return info
 
 _html_element_constructors = {
   'AnchorElement' :
     ElementConstructorInfo(tag='a', opt_params=[('DOMString', 'href')]),
   'AreaElement': 'area',
   'ButtonElement': 'button',
   'BRElement': 'br',
   'BaseElement': 'base',
   'BodyElement': 'body',
@@ skipping 81 matching lines @@
         '\n'
         '  static $RETURN_TYPE $CONSTRUCTOR($PARAMS) {\n'
         '    $CLASS _e = _document.$dom_createElement("$TAG");\n'
         '$!INITS'
         '    return _e;\n'
         '  }\n',
         RETURN_TYPE=rename_type(constructor_info.type_name),
         CONSTRUCTOR=constructor_info.ConstructorFactoryName(rename_type),
         CLASS=class_name,
         TAG=info.tag,
-        PARAMS=constructor_info.ParametersInterfaceDeclaration(rename_type))
+        PARAMS=constructor_info.ParametersInterfaceDeclaration(
+            rename_type, force_optional=True))
     for param in constructor_info.param_infos:
       inits.Emit('    if ($E != null) _e.$E = $E;\n', E=param.name)
 
 # ------------------------------------------------------------------------------
 
 class HtmlDartInterfaceGenerator(object):
   """Generates dart interface and implementation for the DOM IDL interface."""
 
   def __init__(self, options, library_emitter, event_generator, interface,
                backend):
@@ skipping 923 matching lines @@
 
     library_emitter = self._multiemitter.FileEmitter(library_file_path)
     library_file_dir = os.path.dirname(library_file_path)
     auxiliary_dir = os.path.relpath(auxiliary_dir, library_file_dir)
     imports_emitter = library_emitter.Emit(
         self._template, AUXILIARY_DIR=massage_path(auxiliary_dir))
     for path in sorted(self._path_to_emitter.keys()):
       relpath = os.path.relpath(path, library_file_dir)
       imports_emitter.Emit(
           "#source('$PATH');\n", PATH=massage_path(relpath))