Add Windows support.

test/runner/browser/content_shell_test.dart

 // Copyright (c) 2015, 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.
 
 @TestOn("vm")
 
 import 'dart:async';
 
 import 'package:shelf/shelf.dart' as shelf;
 import 'package:shelf/shelf_io.dart' as shelf_io;
 import 'package:shelf_web_socket/shelf_web_socket.dart';
 import 'package:test/src/runner/browser/content_shell.dart';
 import 'package:test/src/util/io.dart';
 import 'package:test/src/utils.dart';
 import 'package:test/test.dart';
 
+import '../../io.dart';
 import '../../utils.dart';
 
 void main() {
   group("running Dart", () {
     // The Dart to serve in the server.
     var dart;
 
     var servePage = (request) {
       var path = shelfUrl(request).path;
 
@@ skipping 109 matching lines @@
       var contentShell = new ContentShell(
           baseUrlForAddress(server.address, server.port));
       return contentShell.close().whenComplete(server.close);
     });
   });
 
   test("reports an error in onExit", () {
     var contentShell = new ContentShell("http://dart-lang.org",
         executable: "_does_not_exist");
     expect(contentShell.onExit, throwsA(isApplicationException(startsWith(
-        "Failed to start content shell: No such file or directory"))));
+        "Failed to start content shell: $noSuchFileMessage"))));
   });
 }