Timer callbacks don't take arguments anymore.

utils/pub/utils.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.
 
 /// Generic utility functions. Stuff that should possibly be in core.
 library utils;
 
 import 'dart:async';
 import 'dart:crypto';
 import 'dart:isolate';
@@ skipping 140 matching lines @@
 /// This is also used to wrap synchronous code that may thrown an exception to
 /// ensure that methods that have both sync and async code only report errors
 /// asynchronously.
 Future defer(callback()) {
   return new Future.immediate(null).then((_) => callback());
 }
 
 /// Returns a [Future] that completes in [milliseconds].
 Future sleep(int milliseconds) {
   var completer = new Completer();
-  new Timer(new Duration(milliseconds: milliseconds),
-      (_) => completer.complete());
+  new Timer(new Duration(milliseconds: milliseconds), completer.complete);
   return completer.future;
 }
 
 /// Configures [future] so that its result (success or exception) is passed on
 /// to [completer].
 void chainToCompleter(Future future, Completer completer) {
   future.then((value) => completer.complete(value),
       onError: (e) => completer.completeError(e.error, e.stackTrace));
 }
 
@@ skipping 162 matching lines @@
 
 /// Add all key/value pairs from [source] to [destination], overwriting any
 /// pre-existing values.
 void mapAddAll(Map destination, Map source) =>
   source.forEach((key, value) => destination[key] = value);
 
 /// Decodes a URL-encoded string. Unlike [decodeUriComponent], this includes
 /// replacing `+` with ` `.
 String urlDecode(String encoded) =>
   decodeUriComponent(encoded.replaceAll("+", " "));