Remove an extra \r\n and fix a test.

lib/src/multipart_request.dart

 // Copyright (c) 2013, 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.
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:math';
 
 import 'base_request.dart';
 import 'byte_stream.dart';
@@ skipping 117 matching lines @@
   ];
 
   /// Returns the header string for a field. The return value is guaranteed to
   /// contain only ASCII characters.
   String _headerForField(String name, String value) {
     var header =
         'content-disposition: form-data; name="${_browserEncode(name)}"';
     if (!isPlainAscii(value)) {
       header = '$header\r\n'
           'content-type: text/plain; charset=utf-8\r\n'
-          'content-transfer-encoding: binary\r\n';
+          'content-transfer-encoding: binary';
     }
     return '$header\r\n\r\n';
   }
 
   /// Returns the header string for a file. The return value is guaranteed to
   /// contain only ASCII characters.
   String _headerForFile(MultipartFile file) {
     var header = 'content-type: ${file.contentType}\r\n'
       'content-disposition: form-data; name="${_browserEncode(file.field)}"';
 
@@ skipping 16 matching lines @@
   /// Returns a randomly-generated multipart boundary string
   String _boundaryString() {
     var prefix = "dart-http-boundary-";
     var list = new List<int>.generate(_BOUNDARY_LENGTH - prefix.length,
         (index) =>
             _BOUNDARY_CHARACTERS[_random.nextInt(_BOUNDARY_CHARACTERS.length)],
         growable: false);
     return "$prefix${new String.fromCharCodes(list)}";
   }
 }