Making FormData able to add Blobs and Files.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 5bbc28b7b4868df6813dddab321a72629d28b600..13fc7403a4f455828a1c151871cab70753fc44fc 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -9010,8 +9010,8 @@ class FormData native "*FormData" {
     return _FormDataFactoryProvider.createFormData(form);
   }
 
-  /// @domName FormData.append; @docsEditable true
-  void append(String name, String value, String filename) native;
+  /// @domName DOMFormData.append; @docsEditable true
+  void append(String name, value, [String filename]) native;
 }
 // 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