Add support for getting OS error information for creating temporary directories

runtime/bin/directory.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.
 
 interface Directory factory _Directory {
   /**
    * Creates a directory object. The path is either a full path or
    * relative to the directory in which the Dart VM was
    * started.
    */
@@ skipping 83 matching lines @@
   void set errorHandler(void errorHandler(String error));
 
   /**
    * Gets the path of this directory.
    */
   final String path;
 }
 
 
 class DirectoryException {
-  const DirectoryException(String this.message);
+  const DirectoryException([String this.message, int this.errorCode = 0]);
   String toString() => "DirectoryException: $message";
   final String message;
+  final int errorCode;
 }