Use rmdir to delete pkgbuild directories on windows

tools/testing/dart/test_runner.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.
 
 /**
  * Classes and methods for executing tests.
  *
  * This module includes:
  * - Managing parallel execution of tests, including timeout checks.
  * - Evaluating the output of each test as pass/fail/crash/timeout.
@@ skipping 400 matching lines @@
 
   Future<ScriptCommandOutputImpl> run() {
     var watch = new Stopwatch()..start();
 
     var source = new io.Directory(_sourceDirectory);
     var destination = new io.Directory(_destinationDirectory);
 
     return destination.exists().then((bool exists) {
       var cleanDirectoryFuture;
       if (exists) {
-        cleanDirectoryFuture = destination.delete(recursive: true);
+        cleanDirectoryFuture = TestUtils.deleteDirectory(_destinationDirectory);
       } else {
         cleanDirectoryFuture = new Future.value(null);
       }
       return cleanDirectoryFuture.then((_) {
         return TestUtils.copyDirectory(_sourceDirectory, _destinationDirectory);
       });
     }).then((_) {
       return new ScriptCommandOutputImpl(
           this, Expectation.PASS, "", watch.elapsed);
     }).catchError((error) {
@@ skipping 2525 matching lines @@
     }
   }
 
   void eventAllTestsDone() {
     for (var listener in _eventListener) {
       listener.allDone();
     }
     _allDone();
   }
 }