Make dartj2s do type conversions on constructor arguments

tools/dom/scripts/systemnative.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 systems to generate
 native binding from the IDL database."""
 
 import emitter
 import os
@@ skipping 375 matching lines @@
 
   def ImplementsMergedMembers(self):
     # We could not add merged functions to implementation class because
     # underlying c++ object doesn't implement them. Merged functions are
     # generated on merged interface implementation instead.
     return False
 
   def CustomJSMembers(self):
     return {}
 
+  def _InputConversion(self, type_name, info):
+    return None
+
   def GenerateCallback(self, info):
     if IsPureInterface(self._interface.id) or IsCustomType(self._interface.id):
       return
 
     interface = self._interface
     if interface.parents:
       supertype = '%sClassId' % interface.parents[0].type.id
     else:
       supertype = '-1'
 
@@ skipping 1509 matching lines @@
 
 def _IsCustom(op_or_attr):
   assert(isinstance(op_or_attr, IDLMember))
   return 'Custom' in op_or_attr.ext_attrs or 'DartCustom' in op_or_attr.ext_attrs
 
 def _IsCustomValue(op_or_attr, value):
   if _IsCustom(op_or_attr):
     return op_or_attr.ext_attrs.get('Custom') == value \
            or op_or_attr.ext_attrs.get('DartCustom') == value
   return False