Enable strict flags for all service tests

runtime/observatory/test/contexts_test.dart

Index: runtime/observatory/test/contexts_test.dart
diff --git a/runtime/observatory/test/contexts_test.dart b/runtime/observatory/test/contexts_test.dart
index be52d119563dbb411ade67692d7f0a532be17c35..7928a74132b370443b21ae84f39ac7836664e7bc 100644
--- a/runtime/observatory/test/contexts_test.dart
+++ b/runtime/observatory/test/contexts_test.dart
@@ -1,6 +1,7 @@
 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // 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.
+// VMOptions=--compile-all --error_on_bad_type --error_on_bad_override --checked
 
 library inbound_references_test;