Migrating a block of dart 1 tests to dart 2

tests/language_strong/closure_self_reference_test.dart

-// Copyright (c) 2014, 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';
-
-// Tests a self-reference of a closure inside a try/catch.
-// Dart2js must not try to box the closure-reference.
-
-main() {
-  var counter = 0;
-  inner(value) {
-    if (value == 0) return 0;
-    try {
-      return inner(value - 1);
-    } finally {
-      counter++;
-    }
-  }
-
-  Expect.equals(0, inner(199));
-  Expect.equals(199, counter);
-}