Remove deprecated parts of dart:async.

tools/testing/dart/utils.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.
 
 library utils;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math' show min;
 import 'dart:convert';
@@ skipping 17 matching lines @@
     if (_sink != null) {
       _sink.close();
       _sink = null;
     }
   }
 
   static String _formatErrorMessage(String msg, error) {
     if (error == null) return msg;
     msg += ": $error";
     // TODO(floitsch): once the dart-executable that is bundled
-    // with the Dart sources is updated, uncomment the following
-    // lines.
-    // var trace = getAttachedStackTrace(error);
+    // with the Dart sources is updated, pass a trace parameter too and do:
     // if (trace != null) msg += "\nStackTrace: $trace";
     return msg;
   }
   static void info(String msg, [error]) {
     msg = _formatErrorMessage(msg, error);
     _print("$_datetime Info: $msg");
   }
 
   static void warning(String msg, [error]) {
     msg = _formatErrorMessage(msg, error);
@@ skipping 111 matching lines @@
 
 class UniqueObject {
   static int _nextId = 1;
   final int _hashCode;
 
   int get hashCode => _hashCode;
   operator==(other) => other is UniqueObject && _hashCode == other._hashCode;
 
   UniqueObject() : _hashCode = ++_nextId;
 }