Fix checked mode failures in service tests

runtime/observatory/tests/service/test_helper.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 test_helper;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'package:observatory/service_io.dart';
@@ skipping 10 matching lines @@
 
 const String _TESTEE_ENV_KEY = 'SERVICE_TEST_TESTEE';
 const Map<String, String> _TESTEE_SPAWN_ENV = const {
   _TESTEE_ENV_KEY: 'true'
 };
 bool _isTestee() {
   return Platform.environment.containsKey(_TESTEE_ENV_KEY);
 }
 
 class _SerivceTesteeRunner {
-  Future run({Future testeeBefore(): null,
-              Future testeeConcurrent(): null,
+  Future run({testeeBefore(): null,
+              testeeConcurrent(): null,
               bool pause_on_start: false,
               bool pause_on_exit: false}) async {
     if (!pause_on_start) {
       if (testeeBefore != null) {
         var result = testeeBefore();
         if (result is Future) {
           await result;
         }
       }
       print(''); // Print blank line to signal that testeeBefore has run.
@@ skipping 293 matching lines @@
         mainArgs: mainArgs,
         vmTests: tests,
         pause_on_start: pause_on_start,
         pause_on_exit: pause_on_exit,
         trace_service: trace_service,
         trace_compiler: trace_compiler,
         verbose_vm: verbose_vm,
         pause_on_unhandled_exceptions: pause_on_unhandled_exceptions);
   }
 }