Fix type typo. :-)

runtime/bin/directory_impl.dart

 // Copyright (c) 2011, 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.
 
 
 // Used for holding error code and error message for failed OS system calls.
 class _OSStatus {
   int _errorCode;
   String _errorMessage;
 }
@@ skipping 126 matching lines @@
       schedule(replyTo);
     };
   }
 
   void enqueue(_DirectoryOperation operation, void callback(result, ignored)) {
     ReceivePort replyPort = new ReceivePort.singleShot();
     replyPort.receive(scheduleWrap(callback));
     operation.replyPort = replyPort.toSendPort();
     _queue.addLast(operation);
     if (_isolate == null) {
-      _isolate = new _FileOperationIsolate();
+      _isolate = new _DirectoryOperationIsolate();
       _isolate.spawn().then((port) {
         schedule(port);
       });
     }
   }
 
   Queue<_DirectoryOperation> _queue;
   _DirectoryOperationIsolate _isolate;
 }
 
@@ skipping 204 matching lines @@
   var _doneHandler;
   var _existsHandler;
   var _createHandler;
   var _createTempHandler;
   var _deleteHandler;
   var _errorHandler;
 
   String _path;
   _DirectoryOperationScheduler _scheduler;
 }