Reapply remove setInterval.

tests/html/transition_event_test.dart

Index: tests/html/transition_event_test.dart
diff --git a/tests/html/transition_event_test.dart b/tests/html/transition_event_test.dart
index c96b46b4dd0b5458e87e67c0a0efad689df90b64..8e041105354de264849adb5c517e88a7d0e59199 100644
--- a/tests/html/transition_event_test.dart
+++ b/tests/html/transition_event_test.dart
@@ -6,6 +6,7 @@ library transition_event_test;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
+import 'dart:async';
 
 main() {
   useHtmlIndividualConfiguration();
@@ -28,14 +29,14 @@ main() {
         element.style.background = 'red';
         element.style.transition = 'opacity .1s';
 
-        window.setTimeout(expectAsync0(() {
+        new Timer(const Duration(milliseconds: 100), expectAsync0(() {
           element.onTransitionEnd.first.then(expectAsync1((e) {
             expect(e is TransitionEvent, isTrue);
             expect(e.propertyName, 'opacity');
           }));
 
           element.style.opacity = '1';
-        }), 100);
+        }));
       }
     });
   });