Fix file test to test for both decomposed and precomposed utf16

tests/standalone/io/directory_non_ascii_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.
 
 import 'dart:io';
 import 'dart:isolate';
 
 main() {
   var port = new ReceivePort();
   Directory scriptDir = new File(new Options().script).directorySync();
   var d = new Directory("${scriptDir.path}/æøå");
+  // On MacOS you get the decomposed utf8 form of file and directory
+  // names from the system. Therefore, we have to check for both here.
+  var precomposed = 'æøå';
+  var decomposed = new String.fromCharCodes([47, 230, 248, 97, 778]);
   d.exists().then((e) {
     Expect.isTrue(e);
     d.create().then((_) {
       new Directory('').createTemp().then((temp) {
         new Directory("${temp.path}/æøå").createTemp().then((temp2) {
-          Expect.isTrue(temp2.path.contains("æøå"));
+          Expect.isTrue(temp2.path.contains(precomposed) ||
+                        temp2.path.contains(decomposed));
           temp2.delete().then((_) {
             temp.delete(recursive: true).then((_) {
               port.close();
             });
           });
         });
       });
     });
   });
 }