Use patching for dart:io.

lib/io/mime_multipart_parser.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.
 
 /**
  * Parser for MIME multipart types of data as described in RFC 2046
  * section 5.1.1. The data to parse is supplied through the [:update:]
  * method. As the data is parsed the following callbacks are called:
  *
  *   [:partStart;
@@ skipping 311 matching lines @@
   Function partDataReceived;
   Function partEnd;
 }
 
 
 class MimeParserException implements Exception {
   const MimeParserException([String this.message = ""]);
   String toString() => "MimeParserException: $message";
   final String message;
 }