Rework Timer interface.

utils/tests/pub/version_solver_test.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.
 
 library pub_update_test;
 
 import 'dart:async';
 import 'dart:io';
 
 import '../../pub/lock_file.dart';
@@ skipping 510 matching lines @@
     return new Future<Pubspec>.immediate(_packages[id.description].pubspec);
   }
 
   void addPackage(Package package) {
     _packages[package.name] = package;
   }
 }
 
 Future fakeAsync(callback()) {
   var completer = new Completer();
-  new Timer(0, (_) {
+  Timer.run(() {
     completer.complete(callback());
   });
 
   return completer.future;
 }
 
 Pair<String, Source> parseSource(String name) {
   var match = new RegExp(r"(.*) from (.*)").firstMatch(name);
   if (match == null) return new Pair<String, Source>(name, source1);
   switch (match[2]) {
   case 'mock1': return new Pair<String, Source>(match[1], source1);
   case 'mock2': return new Pair<String, Source>(match[1], source2);
   case 'root': return new Pair<String, Source>(match[1], null);
   case 'versionless':
     return new Pair<String, Source>(match[1], versionlessSource);
   }
 }