Revert "Make Map constructors return LinkedHashMap."

tests/corelib/map_from_iterables_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";
 import 'dart:collection';
 
 main() {
   positiveTest();
   emptyMapTest();
   fewerKeysIterableTest();
   fewerValuesIterableTest();
   equalElementsTest();
   genericTypeTest();
 }
 
 void positiveTest() {
   var map = new Map.fromIterables([1, 2, 3], ["one", "two", "three"]);
   Expect.isTrue(map is Map);
-  Expect.isTrue(map is LinkedHashMap);
+  Expect.isTrue(map is HashMap);
 
   Expect.equals(3, map.length);
   Expect.equals(3, map.keys.length);
   Expect.equals(3, map.values.length);
 
   Expect.equals("one", map[1]);
   Expect.equals("two", map[2]);
   Expect.equals("three", map[3]);
 }
 
 void emptyMapTest() {
   var map = new Map.fromIterables([], []);
   Expect.isTrue(map is Map);
-  Expect.isTrue(map is LinkedHashMap);
+  Expect.isTrue(map is HashMap);
 
   Expect.equals(0, map.length);
   Expect.equals(0, map.keys.length);
   Expect.equals(0, map.values.length);
 }
 
 void fewerValuesIterableTest() {
   Expect.throws(() => new Map.fromIterables([1,2], [0]));
 }
 
 void fewerKeysIterableTest() {
   Expect.throws(() => new Map.fromIterables([1], [0,2]));
 }
 
 void equalElementsTest() {
   var map = new Map.fromIterables([1, 2, 2], ["one", "two", "three"]);
   Expect.isTrue(map is Map);
-  Expect.isTrue(map is LinkedHashMap);
+  Expect.isTrue(map is HashMap);
 
   Expect.equals(2, map.length);
   Expect.equals(2, map.keys.length);
   Expect.equals(2, map.values.length);
 
   Expect.equals("one", map[1]);
   Expect.equals("three", map[2]);
 }
 
 
 void genericTypeTest() {
   var map = new Map<int, String>.fromIterables(
       [1, 2, 3], ["one", "two", "three"]);
   Expect.isTrue(map is Map<int, String>);
 
   // Make sure it is not just Map<dynamic, dynamic>.
   Expect.isFalse(map is Map<String, dynamic>);
   Expect.isFalse(map is Map<dynamic, int>);
 
   Expect.equals(3, map.length);
   Expect.equals(3, map.keys.length);
   Expect.equals(3, map.values.length);
 
   Expect.equals("one", map[1]);
   Expect.equals("two", map[2]);
   Expect.equals("three", map[3]);
 }