Add @MirrorsUsed annotations to speed up tests.

tests/lib/mirrors/delegate_function_invocation_test.dart

Index: tests/lib/mirrors/delegate_function_invocation_test.dart
diff --git a/tests/lib/mirrors/delegate_function_invocation_test.dart b/tests/lib/mirrors/delegate_function_invocation_test.dart
index d7398ad968ff16ae5753df2875750cad6103c31a..ae9c5a738a62390e9aa62c4fdc062fd6cbd4dc33 100644
--- a/tests/lib/mirrors/delegate_function_invocation_test.dart
+++ b/tests/lib/mirrors/delegate_function_invocation_test.dart
@@ -2,8 +2,9 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library test.delgate_function_invocation;
+library test.delegate_function_invocation;
 
+@MirrorsUsed(targets: "test.delegate_function_invocation")
 import 'dart:mirrors';
 
 import 'package:expect/expect.dart';