Implement support for application/x-www-form-urlencoded' form data in HttpBodyHandler.

tests/standalone/io/http_body_test.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:io';
 import 'dart:utf';
 
 import 'package:expect/expect.dart';
 
 void testHttpClientResponseBody() {
@@ skipping 95 matching lines @@
                 Expect.equals(body.contentType.mimeType, "application/json");
                 Expect.mapEquals(expectedBody, body.body);
                 break;
 
               case "binary":
                 Expect.equals(body.contentType, null);
                 Expect.listEquals(expectedBody, body.body);
                 break;
 
               case "form":
-                Expect.equals(body.contentType.mimeType, 'multipart/form-data');
+                var mimeType = body.contentType.mimeType;
+                Expect.isTrue(
+                    mimeType == 'multipart/form-data' ||
+                    mimeType == 'application/x-www-form-urlencoded');
                 Expect.setEquals(expectedBody.keys.toSet(),
                                  body.body.keys.toSet());
                 for (var key in expectedBody.keys) {
                   if (body.body[key] is HttpBodyFileUpload) {
                     Expect.equals(expectedBody[key]['contentType'],
                                   body.body[key].contentType.toString());
                     Expect.equals(expectedBody[key]['filename'],
                                   body.body[key].filename);
                     if (body.body[key].content is String) {
                       Expect.equals(expectedBody[key]['content'],
@@ skipping 106 matching lines @@
 --AaB03x\r
 Content-Disposition: form-data; name="files"; filename="myfile"\r
 Content-Type: application/json\r
 \r
 File content\r
 --AaB03x--\r\n'''.codeUnits,
        { "files": { 'filename': 'myfile',
                     'contentType': 'application/json',
                     'content': 'File content'} },
        "form");
+
+  test('application/x-www-form-urlencoded',
+       '%E5%B9%B3%3D%E4%BB%AE%E5%90%8D=%26%2324179%3B%26%2320206%3B%26%'
+       '2321517%3B&b=%26%2324179%3B%26%2320206%3B%26%2321517%3B'.codeUnits,
+       { 'b' : '平仮名',
+         '平=仮名' : '平仮名'},
+       "form");
 }
 
 void main() {
   testHttpClientResponseBody();
   testHttpServerRequestBody();
 }