Update dart:io to convert strings between UTF8 and current code page

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("${scriptDir.path}/æøå");
+  d.exists().then((e) {
+    Expect.isTrue(e);
+    d.create().then((_) {
+      new Directory('').createTemp().then((temp) {
+        new Directory("${temp.path}/æøå").createTemp().then((temp2) {
+          Expect.isTrue(temp2.path.contains("æøå"));
+          temp2.delete().then((_) {
+            temp.delete(recursive: true).then((_) {
+              port.close();
+            });
+          });
+        });
+      });
+    });
+  });
+}