Fix file test to test for both decomposed and precomposed utf16

tests/standalone/io/directory_non_ascii_sync_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';
 
 main() {
   Directory scriptDir = new File(new Options().script).directorySync();
   var d = new Directory("${scriptDir.path}/æøå");
+  // On MacOS you get the decomposed utf8 form of file and directory
+  // names from the system. Therefore, we have to check for both here.
+  var precomposed = 'æøå';
+  var decomposed = new String.fromCharCodes([47, 230, 248, 97, 778]);
   Expect.isTrue(d.existsSync());
   d.createSync();
   var temp = new Directory('').createTempSync();
   var temp2 = new Directory("${temp.path}/æøå").createTempSync();
-  Expect.isTrue(temp2.path.contains("æøå"));
+  Expect.isTrue(temp2.path.contains(precomposed) ||
+                temp2.path.contains(decomposed));
   temp2.deleteSync();
   temp.deleteSync(recursive: true);
 }