Migrated test block 17 to Dart 2.0.

tests/corelib_strong/null_test.dart

-// 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.
-
-import "package:expect/expect.dart";
-
-// Test that Null inherits properties from Object.
-
-main() {
-  var x;
-
-  Expect.isTrue(x is Object);
-  Expect.isTrue(x is dynamic);
-  Expect.isTrue(x is! String);
-  Expect.isTrue(x is! int);
-
-  // These shouldn't throw.
-  x.runtimeType;
-  x.toString();
-  x.hashCode;
-
-  // operator== is inherited from Object. It's the same as identical.
-  // It's not really testable.
-  Expect.isTrue(identical(x, null));
-  Expect.isTrue(x == null);
-
-  // Methods can be closurized and yields the same result.
-  var ts = x.toString;
-  Expect.equals(null.toString(), ts());
-
-  // noSuchMethod is tested in null_nosuchmethod_test.dart.
-}