Merge pull request #22 from MichaelRFairhurst/remove-async-import

Remove unused dart:async import
diff --git a/test/default_test.dart b/test/default_test.dart
index bc56e48..fbf1a29 100644
--- a/test/default_test.dart
+++ b/test/default_test.dart
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import 'dart:async';
-
 import 'package:clock/clock.dart';
 
 import 'package:test/test.dart';