Modify tests to use Directory.systemTemp

tests/standalone/io/windows_file_system_async_links_test.dart

 // Copyright (c) 2013, 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 "dart:async";
 import "dart:io";
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
 
 
 class FutureExpect {
   static Future isTrue(Future<bool> result) =>
       result.then((value) => Expect.isTrue(value));
   static Future isFalse(Future<bool> result) =>
       result.then((value) => Expect.isFalse(value));
   static Future equals(expected, Future result) =>
       result.then((value) => Expect.equals(expected, value));
   static Future listEquals(expected, Future result) =>
       result.then((value) => Expect.listEquals(expected, value));
   static Future throws(Future result) =>
       result.then((value) {
         throw new ExpectException(
             "FutureExpect.throws received $value instead of an exception");
         }, onError: (_) => null);
 }
 
 
 Future testJunctionTypeDelete() {
-  return new Directory('').createTemp().then((temp) {
+  return Directory.systemTemp
+                  .createTemp('dart_windows_file_system_async_links')
+                  .then((temp) {
     var x = '${temp.path}${Platform.pathSeparator}x';
     var y = '${temp.path}${Platform.pathSeparator}y';
     return new Directory(x).create()
     .then((_) => new Link(y).create(x))
     .then((_) => FutureExpect.isTrue(new Directory(y).exists()))
     .then((_) => FutureExpect.isTrue(new Directory(x).exists()))
     .then((_) => FutureExpect.isTrue(FileSystemEntity.isLink(y)))
     .then((_) => FutureExpect.isFalse(FileSystemEntity.isLink(x)))
     .then((_) => FutureExpect.isTrue(FileSystemEntity.isDirectory(y)))
     .then((_) => FutureExpect.isTrue(FileSystemEntity.isDirectory(x)))
@@ skipping 56 matching lines @@
 }
 
 
 main() {
   // Links on other platforms are tested by file_system_[async_]links_test.
   if (Platform.operatingSystem == 'windows') {
     asyncStart();
     testJunctionTypeDelete().then((_) => asyncEnd());
   }
 }