Make OptionElement construtor arguments named optional parameters.

tools/dom/scripts/htmldartgenerator.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
 from generator import AnalyzeOperation, ConstantOutputOrder, \
     DartDomNameOfAttribute, FindMatchingAttribute, \
     TypeOrNothing, ConvertToFuture, GetCallbackInfo
 from copy import deepcopy
-from htmlrenamer import convert_to_future_members, keep_overloaded_members, \
-    private_html_members, dom_private_html_members, renamed_html_members, renamed_overloads, \
-    removed_html_members
+from htmlrenamer import convert_to_future_members, custom_html_constructors, \
+    keep_overloaded_members, private_html_members, dom_private_html_members, renamed_html_members, \
+    renamed_overloads, removed_html_members
 import logging
 import monitored
 import sys
 
 _logger = logging.getLogger('htmldartgenerator')
 
 # Types that are accessible cross-frame in a limited fashion.
 # In these cases, the base type (e.g., WindowBase) provides restricted access
 # while the subtype (e.g., Window) provides full access to the
 # corresponding objects if there are from the same frame.
@@ skipping 564 matching lines @@
                 info.callback_args[1].is_optional else ''))),
         FUTURE_GENERIC = ('' if len(callback_info.param_infos) == 0 or
             not callback_info.param_infos[0].type_id else
             '<%s>' % self._DartType(callback_info.param_infos[0].type_id)),
         ORIGINAL_FUNCTION = html_name)
 
   def EmitHelpers(self, base_class):
     if not self._members_emitter:
       return
 
-    if base_class != self.RootClassName():
+    if (base_class != self.RootClassName() and
+          self._interface.id not in custom_html_constructors):
       self._members_emitter.Emit(
           '  // To suppress missing implicit constructor warnings.\n'
           '  factory $CLASSNAME._() { '
           'throw new UnsupportedError("Not supported"); }\n',
           CLASSNAME=self._interface_type_info.implementation_name())
 
   def DeclareAttribute(self, attribute, type_name, attr_name, read_only):
     """ Declares an attribute but does not include the code to invoke it.
     """
     if read_only:
@@ skipping 82 matching lines @@
 
   def SecureBaseName(self, type_name):
     if type_name in _secure_base_types:
       return _secure_base_types[type_name]
 
   def _DartType(self, type_name):
     return self._type_registry.DartType(type_name)
 
   def _TypeInfo(self, type_name):
     return self._type_registry.TypeInfo(type_name)