Fix null.runtimeType, reflect(null).type.superinterfaces, and reflect(null).getField.

tests/lib/mirrors/null2_test.dart

Index: tests/lib/mirrors/null2_test.dart
diff --git a/tests/lib/mirrors/unmangled_type_test.dart b/tests/lib/mirrors/null2_test.dart
similarity index 62%
copy from tests/lib/mirrors/unmangled_type_test.dart
copy to tests/lib/mirrors/null2_test.dart
index dbc6b62437908677c6fb6c1dab670b8d0dd7d2b6..4c5590d398f9ad7f7d251438ffbb1e3f2104c6cc 100644
--- a/tests/lib/mirrors/unmangled_type_test.dart
+++ b/tests/lib/mirrors/null2_test.dart
@@ -2,14 +2,15 @@
 // 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.
 
+library test.null_test;
+
 import 'dart:mirrors';
 
 import 'package:expect/expect.dart';
 
-class Foo {
-}
-
 main() {
-  Expect.stringEquals('Foo', '${new Foo().runtimeType}');
-  Expect.stringEquals('foo', MirrorSystem.getName(new Symbol('foo')));
+  InstanceMirror nullMirror = reflect(null);
+  for (int i = 0; i < 10; i++) {
+    Expect.isTrue(nullMirror.getField(#hashCode).reflectee is int);
+  }
 }