Change dart:io Platform.script to return a Uri.

tests/standalone/io/http_server_close_response_after_error_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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
 import 'dart:async';
 import 'dart:io';
 
 const CLIENT_SCRIPT = "http_server_close_response_after_error_client.dart";
 
 void main() {
   HttpServer.bind("127.0.0.1", 0)
       .then((server) {
         server.listen(
             (request) {
               request.listen(
                   null,
                   onError: (e) {},
                   onDone: () {
                     request.response.close();
                   });
             });
-        var path = new Uri.file(Platform.script);
         Process.run(Platform.executable,
-                    [path.resolve(CLIENT_SCRIPT).toString(),
+                    [Platform.script.resolve(CLIENT_SCRIPT).toString(),
                      server.port.toString()])
             .then((result) {
               if (result.exitCode != 0) throw "Bad exit code";
               server.close();
             });
       });
 }