Make observatory tests analyzer clean

runtime/observatory/tests/service/library_dependency_test.dart

Index: runtime/observatory/tests/service/library_dependency_test.dart
diff --git a/runtime/observatory/tests/service/library_dependency_test.dart b/runtime/observatory/tests/service/library_dependency_test.dart
index b198f01874a5bbab26359f6ff0dd1c20abd8b259..829726199c8bb01b5c4b96bc1851da905f1c4c45 100644
--- a/runtime/observatory/tests/service/library_dependency_test.dart
+++ b/runtime/observatory/tests/service/library_dependency_test.dart
@@ -15,7 +15,8 @@ var tests = [
 
 (Isolate isolate) async {
   var lib = await isolate.rootLibrary.load();
-
+  // Use mirrors to shutup the analyzer.
+  mirrors.currentMirrorSystem();
   importOf(String uri) {
     return lib.dependencies.singleWhere((dep) => dep.target.uri == uri);
   }
@@ -35,6 +36,10 @@ var tests = [
   expect(importOf("dart:convert").isDeferred, isTrue);
   expect(importOf("dart:convert").prefix, equals("convert"));
 },
+
+(Isolate isolate) async {
+  return convert.loadLibrary();
+}
 ];
 
 main(args) => runIsolateTests(args, tests);