Reapply expanding overloaded functions into separate functions.

tests/html/form_data_test.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 FormDataTest;
 
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 
@@ skipping 35 matching lines @@
         var form = new FormData(new FormElement());
         expect(form, isNotNull);
         expect(form, isFormData);
       });
 
       test('appendTest', () {
         var form = new FormData();
         form.append('test', '1');
         form.append('username', 'Elmo');
         form.append('address', '1 Sesame Street');
-        form.append('password', '123456', 'foo');
+        form.append('password', '123456');
         expect(form, isNotNull);
       });
 
       test('appendBlob', () {
         var form = new FormData();
         var blob = new Blob(
             ['Indescribable... Indestructible! Nothing can stop it!'],
             'text/plain');
         form.append('theBlob', blob, 'theBlob.txt');
       });
@@ skipping 15 matching lines @@
           expect(xhr.responseText.contains(blobString), true);
         }));
         xhr.onError.listen((e) {
           fail('$e');
         });
         xhr.send(form);
       });
     }
   });
 }