Mirror test updated cf. API change

tests/compiler/dart2js/mirrors_test.dart

Index: tests/compiler/dart2js/mirrors_test.dart
diff --git a/tests/compiler/dart2js/mirrors_test.dart b/tests/compiler/dart2js/mirrors_test.dart
index 96aa7e899d8c2594c49e8a1dd0075b41f72c81a9..76dcaa0759c177e8d03e14331033bfff6d9944b9 100644
--- a/tests/compiler/dart2js/mirrors_test.dart
+++ b/tests/compiler/dart2js/mirrors_test.dart
@@ -281,9 +281,7 @@ void testBaz(MirrorSystem system, LibraryMirror helperLibrary,
   Expect.isFalse(barInterface.isDeclaration, "Interface type is declaration");
   var barInterfaceTypeArguments = barInterface.typeArguments();
   Expect.isNotNull(barInterfaceTypeArguments, "Type arguments are missing");
-  // TODO(johnniwinther): Ensure type arguments on supertypes. Expected result
-  // should have been 1:
-  Expect.equals(0, barInterfaceTypeArguments.length,
+  Expect.equals(1, barInterfaceTypeArguments.length,
                 "Type arguments is empty");
 
   Expect.throws(() => bazClass.typeArguments(),