Observatory: remove unused imports

runtime/observatory/tests/service/reload_sources_test.dart

Index: runtime/observatory/tests/service/reload_sources_test.dart
diff --git a/runtime/observatory/tests/service/reload_sources_test.dart b/runtime/observatory/tests/service/reload_sources_test.dart
index 4c8b4d975941b8c184b8cc51a3cd5d55501e1e01..64f5eac816e979593449014ada1f461f7a3aa7a1 100644
--- a/runtime/observatory/tests/service/reload_sources_test.dart
+++ b/runtime/observatory/tests/service/reload_sources_test.dart
@@ -3,8 +3,6 @@
 // BSD-style license that can be found in the LICENSE file.
 // VMOptions=--error_on_bad_type --error_on_bad_override
 
-import 'package:observatory/service_io.dart';
-import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 import 'dart:developer';
 import 'service_test_common.dart';