Migrated test block 13 to Dart 2.0.

tests/corelib_2/linked_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.
 
 // Dart test for linked hash-maps.
 library linkedHashMap.test;
 
 import "package:expect/expect.dart";
 import 'dart:collection' show LinkedHashMap;
 
@@ skipping 96 matching lines @@
 
     clear();
     map.values.forEach(testForEachValue);
     verifyValues(valuesAfterAUpdate);
   }
 }
 
 main() {
   LinkedHashMapTest.testMain();
 }