Fix issue with async callbacks that get called synchronously while running test case function causi…

pkg/unittest/lib/src/expect.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.
 
 part of matcher;
 
 /** The objects thrown by the default failure handler. */
 class TestFailure {
   String _message;
 
   get message => _message;
   set message(String value) => _message = value;
 
   TestFailure(String message) : _message = message;
 
   String toString() => _message;
 }
 
 /**
  * Some matchers, like those for Futures and exception testing,
  * can fail in asynchronous sections, and throw exceptions.
  * A user of this library will typically want to catch and handle 
  * such exceptions. The [wrapAsync] property is a function that
  * can wrap callbacks used by these Matchers so that they can be
  * used safely. For example, the unittest library will set this
  * to be expectAsync1. By default this is an identity function.
  */
-Function wrapAsync = (f) => f;
+Function wrapAsync = (f, [id]) => f;
 
 /**
  * This is the main assertion function. It asserts that [actual]
  * matches the [matcher]. [reason] is optional and is typically not
  * supplied, as a reason is generated from the matcher; if [reason]
  * is included it is appended to the reason generated by the matcher.
  *
  * [matcher] can be a value in which case it will be wrapped in an
  * [equals] matcher.
  *
@@ skipping 134 matching lines @@
  * formatter is returned; this allows custom expect handlers to easily
  * get a reference to the default formatter.
  */
 ErrorFormatter configureExpectFormatter([ErrorFormatter formatter = null]) {
   if (formatter == null) {
     formatter = _defaultErrorFormatter;
   }
   return _assertErrorFormatter = formatter;
 }