Remove an old incorrect piece of documentation.

pkg/unittest/lib/unittest.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.
 
 /**
  * A library for writing dart unit tests.
  *
  * ## Installing ##
  *
  * Use [pub][] to install this package. Add the following to your `pubspec.yaml`
@@ skipping 120 matching lines @@
  * Timer.run()], as the Future exception handler may not capture exceptions
  * in such code.
  *
  * Note: due to some language limitations we have to use different functions
  * depending on the number of positional arguments of the callback. In the
  * future, we plan to expose a single `expectAsync` function that can be used
  * regardless of the number of positional arguments. This requires new langauge
  * features or fixes to the current spec (e.g. see
  * [Issue 2706](http://dartbug.com/2706)).
  *
- * Meanwhile, we plan to add this alternative API for callbacks of more than 2
- * arguments or that take named parameters. (this is not implemented yet,
- * but will be coming here soon).
- *
- *     import 'package:unittest/unittest.dart';
- *     import 'dart:isolate';
- *     main() {
- *       test('callback is executed', () {
- *         // indicate ahead of time that an async callback is expected.
- *         var async = startAsync();
- *         Timer.run(() {
- *           // Guard the body of the callback, so errors are propagated
- *           // correctly.
- *           guardAsync(() {
- *             int x = 2 + 3;
- *             expect(x, equals(5));
- *           });
- *           // indicate that the asynchronous callback was invoked.
- *           async.complete();
- *         });
- *       });
- *     }
- *
  * [pub]: http://pub.dartlang.org
  * [pkg]: http://pub.dartlang.org/packages/unittest
  */
 library unittest;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:isolate';
 import 'dart:math' show max;
 import 'matcher.dart';
@@ skipping 713 matching lines @@
 
   if (!formatStacks) return trace;
 
   // Format the stack trace by removing everything above TestCase._runTest,
   // which is usually going to be irrelevant. Also fold together unittest and
   // core library calls so only the function the user called is visible.
   return new Trace(trace.frames.takeWhile((frame) {
     return frame.package != 'unittest' || frame.member != 'TestCase._runTest';
   })).terse.foldFrames((frame) => frame.package == 'unittest' || frame.isCore);
 }