Timer callback doesn't take an argument anymore.

utils/pub/io.dart

Index: utils/pub/io.dart
diff --git a/utils/pub/io.dart b/utils/pub/io.dart
index ebdb35a80994a1f0aa580234ebd15f660a9ed8c7..a8ec15891557bcbc5d9f96e9bbbe13b0035bdb4f 100644
--- a/utils/pub/io.dart
+++ b/utils/pub/io.dart
@@ -593,7 +593,7 @@ Future _doProcess(Function fn, String executable, List<String> args,
 Future timeout(Future input, int milliseconds, String description) {
   bool completed = false;
   var completer = new Completer();
-  var timer = new Timer(new Duration(milliseconds: milliseconds), (_) {
+  var timer = new Timer(new Duration(milliseconds: milliseconds), () {
     completed = true;
     completer.completeError(new TimeoutException(
         'Timed out while $description.'));