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

tests/standalone/vmservice/test_helper.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.
 
 library vmservice_test_helper;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'package:expect/expect.dart';
@@ skipping 62 matching lines @@
   Future onRequestCompleted(Map response);
 }
 
 class TestLauncher {
   final String script;
   Process process;
 
   TestLauncher(this.script);
 
   String get scriptPath {
-    var dartScript = Platform.script.toFilePath();
+    var dartScript = Platform.script;
     var splitPoint = dartScript.lastIndexOf(Platform.pathSeparator);
     var scriptDirectory = dartScript.substring(0, splitPoint);
     return scriptDirectory + Platform.pathSeparator + script;
   }
 
   Future<int> launch() {
     String dartExecutable = Platform.executable;
     print('** Launching $scriptPath');
     return Process.start(dartExecutable,
                          ['--enable-vm-service:0', scriptPath]).then((p) {
@@ skipping 153 matching lines @@
       });
     });
     return Future.wait(requests).then((a) {
       a.forEach((FieldRequestHelper field) {
         fields[field.field['user_name']] = field.field;
       });
       return this;
     });
   }
 }