Migrate test block 9 to Dart 2.0

tests/corelib_strong/hash_map_test.dart

-// Copyright (c) 2011, 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.
-//
-// VMOptions=
-// VMOptions=--use_internal_hash_map
-
-import "package:expect/expect.dart";
-
-// Test program for the HashMap class.
-
-class HashMapTest {
-  static testMain() {
-    var m = new Map();
-    Expect.equals(0, m.length);
-    Expect.equals(true, m.isEmpty);
-    m["one"] = 1;
-    Expect.equals(1, m.length);
-    Expect.equals(false, m.isEmpty);
-    Expect.equals(1, m["one"]);
-  }
-}
-
-main() {
-  HashMapTest.testMain();
-}