Make the repeating argument to timers optional.

client/testing/unittest/unittest_vm.dart

 // Copyright (c) 2011, 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.
 
 /**
  * A simple unit test library for running tests on the VM.
  */
 #library("unittest");
 
 #source("shared.dart");
 
 _platformInitialize() {
   // Do nothing.
 }
 
 _platformDefer(void callback()) {
   new Timer((timer) {
     callback();
-  }, 0, false);
+  }, 0);
 }
 
 _platformStartTests() {
   // Do nothing.
 }
 
 _platformCompleteTests(int testsPassed, int testsFailed, int testsErrors) {
   // Print each test's result.
   for (final test in _tests) {
     print('${test.result.toUpperCase()}: ${test.description}');
 
     if (test.message != '') {
       print('  ${test.message}');
     }
   }
 
   // Show the summary.
   print('');
 
   if (testsPassed == 0 && testsFailed == 0 && testsErrors == 0) {
     print('No tests found.');
   } else if (testsFailed == 0 && testsErrors == 0) {
     print('All $testsPassed tests passed.');
   } else {
     print('$testsPassed PASSED, $testsFailed FAILED, $testsErrors ERRORS');
   }
 }