Migrate block 162 to Dart 2.0.

tests/language/type_variable_closure_test.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file

[eernst, 2017/09/04 17:04:57]

Lost coverage: don't delete this 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";
-
-class C<T> {
-  C.foo() {
-    x = (a) => a is T;
-  }
-  C.bar() {
-    x = (a) => a is! T;
-  }
-  C.baz() {
-    x = (a) => a as T;
-  }
-  var x;
-}
-
-main() {
-  Expect.isTrue(new C<int>.foo().x(1));
-  Expect.isFalse(new C<int>.foo().x('1'));
-  Expect.isFalse(new C<int>.bar().x(1));
-  Expect.isTrue(new C<int>.bar().x('1'));
-  Expect.equals(new C<int>.baz().x(1), 1);
-  Expect.throws(() => new C<int>.baz().x('1'));
-}