Add a new implementation of HashMap that uses JS objects for its (multiple) hash tables.

pkg/unittest/test/matchers_test.dart

 // Copyright (c) 2012, 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.
 
 library unittestTests;
 import 'package:unittest/unittest.dart';
 import 'dart:async';
+import 'dart:collection';
 part 'test_utils.dart';
 
 doesNotThrow() {}
 doesThrow() { throw 'X'; }
 
 class PrefixMatcher extends BaseMatcher {
   final String _prefix;
   const PrefixMatcher(this._prefix);
   bool matches(item, MatchState matchState) {
     return item is String &&
@@ skipping 517 matching lines @@
       var b = new Map();
       b['foo'] = 'bar';
       var c = new Map();
       c['bar'] = 'foo';
       shouldPass(a, equals(b));
       shouldFail(b, equals(c),
           "Expected: <{bar: foo}> but: missing map key 'bar'.");
     });
 
     test('equals with different lengths', () {
-      var a = new Map();
+      var a = new LinkedHashMap();
       a['foo'] = 'bar';
-      var b = new Map();
+      var b = new LinkedHashMap();
       b['foo'] = 'bar';
       b['bar'] = 'foo';
-      var c = new Map();
+      var c = new LinkedHashMap();
       c['bar'] = 'foo';
       c['barrista'] = 'caffeine';
       shouldFail(a, equals(b),
-          "Expected: <{bar: foo, foo: bar}> "
+          "Expected: <{foo: bar, bar: foo}> "
           "but: different map lengths; missing map key 'bar'.");
       shouldFail(b, equals(a),
           "Expected: <{foo: bar}> "
           "but: different map lengths; extra map key 'bar'.");
       shouldFail(b, equals(c),
           "Expected: <{bar: foo, barrista: caffeine}> "
           "but: missing map key 'barrista'.");
       shouldFail(c, equals(b),
-          "Expected: <{bar: foo, foo: bar}> "
+          "Expected: <{foo: bar, bar: foo}> "
           "but: missing map key 'foo'.");
       shouldFail(a, equals(c),
           "Expected: <{bar: foo, barrista: caffeine}> "
           "but: different map lengths; missing map key 'bar'.");
       shouldFail(c, equals(a),
           "Expected: <{foo: bar}> "
           "but: different map lengths; missing map key 'foo'.");
     });
 
     test('contains', () {
@@ skipping 128 matching lines @@
       var w = new Widget();
       w.price = 10;
       shouldPass(w, new HasPrice(greaterThan(0)));
       shouldFail(w, new HasPrice(greaterThan(10)),
           'Expected: Widget with a price that is a value greater than <10> '
           'but: price was <10>.');
     });
   });
 }