Migrated test block 17 to Dart 2.0.

tests/corelib_2/map_values3_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.
 
 import "package:expect/expect.dart";
 
 main() {
   var map1 = <int, String>{1: "42", 2: "499"};
   var map2 = <int, String>{};
   var map3 = const <int, String>{3: "42", 4: "499"};
@@ skipping 33 matching lines @@
   Expect.equals(2, map5.values.length);
   // new Map gives a LinkedHashMap, so we know the order.
   Expect.isTrue(map5.values.first == "43");
   Expect.isTrue(map5.values.last == "500");
 
   Expect.isTrue(map6.values is Iterable<String>);
   Expect.isFalse(map6.values is Iterable<bool>);
   Expect.isFalse(map6.values is List);
   Expect.equals(0, map6.values.length);
 }