Version 1.5.3

dart/tools/dom/scripts/htmldartgenerator.py

Index: dart/tools/dom/scripts/htmldartgenerator.py
===================================================================
--- dart/tools/dom/scripts/htmldartgenerator.py	(revision 37971)
+++ dart/tools/dom/scripts/htmldartgenerator.py	(working copy)
@@ -358,8 +358,9 @@
       for i in reversed(range(0, argument_count)):
         argument = signatures[signature_index][i]
         parameter_name = parameter_names[i]
-        test_type = self._DartType(argument.type.id)
 
+        test_type = self._NarrowToImplementationType(argument.type.id)
+
         if test_type in ['dynamic', 'Object']:
           checks.append('%s != null' % parameter_name)
         elif not can_omit_type_check(test_type, i):
@@ -755,6 +756,12 @@
     if type_name in _secure_base_types:
       return _secure_base_types[type_name]
 
+  def _NarrowToImplementationType(self, type_name):
+    return self._type_registry.TypeInfo(type_name).narrow_dart_type()
+
+  def _NarrowInputType(self, type_name):
+    return self._NarrowToImplementationType(type_name)
+
   def _DartType(self, type_name):
     return self._type_registry.DartType(type_name)