Prevent more timeouts.

pkg/template_binding/test/utils.dart

Index: pkg/template_binding/test/utils.dart
diff --git a/pkg/template_binding/test/utils.dart b/pkg/template_binding/test/utils.dart
index 35e37b3e73275004fb492af934f92c6f3535b737..d2d73792af1dcc11e6cf2413bd4ca5354becccaf 100644
--- a/pkg/template_binding/test/utils.dart
+++ b/pkg/template_binding/test/utils.dart
@@ -7,6 +7,10 @@ library template_binding.test.utils;
 import 'dart:async';
 import 'dart:html';
 import 'package:observe/observe.dart';
+
+// Note: tests that import 'utils.dart' rely on the following line to make test
+// smaller for dart2js and prevent timeouts in the test bots.
+import 'package:observe/mirrors_used.dart';
 import 'package:template_binding/template_binding.dart';
 export 'package:observe/src/dirty_check.dart' show dirtyCheckZone;