Reverting setTimeout removal.

tests/html/history_test.dart

 library HistoryTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
-import 'dart:async';
 
 main() {
   useHtmlIndividualConfiguration();
 
   group('supported_state', () {
     test('supportsState', () {
       expect(History.supportsState, true);
     });
   });
 
@@ skipping 20 matching lines @@
 
     test('back', () {
       expect(() {
         window.history.pushState(null, document.title, '?dummy1');
         window.history.pushState(null, document.title, '?dummy2');
         var length = window.history.length;
 
         expect(window.location.href.endsWith('dummy2'), isTrue);
 
         // Need to wait a frame or two to let the pushState events occur.
-        new Timer(const Duration(milliseconds: 100), expectAsync0(() {
+        window.setTimeout(expectAsync0(() {
           window.onPopState.first.then(expectAsync1((_){
             expect(window.history.length, length);
             expect(window.location.href.endsWith('dummy1'), isTrue);
           }));
 
           window.history.back();
-        }));
+        }), 100);
       }, expectation);
     });
 
     test('replaceState', () {
       expect(() {
         var length = window.history.length;
 
         window.history.replaceState(null, document.title, '?foo=baz');
         expect(window.history.length, length);
         expect(window.location.href.endsWith('foo=baz'), isTrue);
@@ skipping 11 matching lines @@
       var expectation = HashChangeEvent.supported ? returnsNormally : throws;
       expect(() {
         var event = new HashChangeEvent('change', oldUrl:'old', newUrl: 'new');
         expect(event is HashChangeEvent, true);
         expect(event.oldUrl, 'old');
         expect(event.newUrl, 'new');
       }, expectation);
     });
   });
 }