Commit Martin's patch for pub + lib_v2.

pkg/http/lib/src/multipart_file.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.
 
 library multipart_file;
 
+import 'dart:async';
 import 'dart:io';
 
 import 'utils.dart';
 
 /// A file to be uploaded as part of a [MultipartRequest]. This doesn't need to
 /// correspond to a physical file.
 class MultipartFile {
   /// The name of the form field for the file.
   final String field;
 
@@ skipping 79 matching lines @@
   // [MultipartRequest]. This returns an [InputStream] that should emit the body
   // of the file. The stream may be closed to indicate an empty file.
   InputStream finalize() {
     if (isFinalized) {
       throw new StateError("Can't finalize a finalized MultipartFile.");
     }
     _isFinalized = true;
     return _stream;
   }
 }