Mark form_data_test as failing in dart2js.

tests/html/html.status

 # 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.
 
 xhr_cross_origin_test: Skip # http://dartbug.com/5645
 
 window_open_test: Fail, Pass # http://dartbug.com/5151
 
 event_test: Skip  # Issue 1996
 webgl_1_test: Skip  # Issue 1495
@@ skipping 193 matching lines @@
 
 [ $compiler == dart2js ]
 transferables_test: Skip # until isInstance works in dart2js
 
 [ $compiler == dart2js && ($runtime == drt || $runtime == ff) ]
 request_animation_frame_test: Skip # Async test hangs.
 
 [ $compiler == dart2js && ($runtime == drt || $runtime == chrome || $runtime == ff || $runtime == safari) ]
 isolates_test: Skip   # Timeout because leg does not support web workers.
 typed_arrays_1_test: Fail # dart2js doesn't support is checks with generic types.
+form_data_test: Fail # Wrong JavaScript type name for FormData, issue 5681.
 
 [ $compiler == dart2js && $runtime == ff && $system == linux]
 indexeddb_3_test: Fail  # Caught Error: DATA_ERR: DOM IDBDatabase Exception 5 Error: The data provided does not meet the requirements of the function.
 
 [ $compiler == dart2js && $runtime == ff ]
 xhr_test: Skip # Timeout
 inner_frame_test: Skip # Timeout
 svg_3_test: Skip # Timeout
 documentfragment_test: Skip # Timeout
 
 [ $compiler == dart2js && $runtime == chrome && $system == windows]
 css_test: Pass, Fail # Issue #2823
 
 [ $compiler == dart2js && $runtime == ff && $system == windows]
 js_interop_2_test: Fail # Issue 4658.
 js_interop_3_test: Fail # Issue 4658.
 
 [ $compiler == dart2js && $checked && $browser]
 fileapi_test: Fail # TypeError: Object #<DirectoryEntry> has no method 'get$name'