Fix a bug in overload dispatch.

lib/dom/scripts/systemnative.py

Index: lib/dom/scripts/systemnative.py
diff --git a/lib/dom/scripts/systemnative.py b/lib/dom/scripts/systemnative.py
index 8cbcb6bccce202ea57188e098ede11d015c9a6a1..eb34854808122b54eafc5047fd8d0d0b289357d6 100644
--- a/lib/dom/scripts/systemnative.py
+++ b/lib/dom/scripts/systemnative.py
@@ -1022,7 +1022,7 @@ class NativeImplementationGenerator(object):
       for (position, param) in enumerate(info.param_infos):
         if position < len(operation.arguments):
           arg = operation.arguments[position]
-          dart_type = DartType(arg.type.id)
+          dart_type = self._DartType(arg.type.id)

[podivilov, 2012/05/28 13:00:09]

DOM interfaces named after idl interfaces have gone when dart:dom was merged
into dart:html. We temporary use fake interfaces named like '_Element' for
overload dispatch. This will gone once native wrappers implement dart:html
interfaces.

           if dart_type == param.dart_type:
             # The overload type matches the method parameter type exactly.  We
             # will have already tested this type in checked mode, and the target