pkg/shelf: marked message_test as RuntimeError due to dart2js bug

pkg/pkg.status

Index: pkg/pkg.status
diff --git a/pkg/pkg.status b/pkg/pkg.status
index 9dbc34343359ac56abd9269eaab5aff8770c230a..f4265e8bce80c61a2ef92aa11930bf783a791969 100644
--- a/pkg/pkg.status
+++ b/pkg/pkg.status
@@ -58,9 +58,10 @@ collection/test/equality_test/03: Fail # Issue 1533
 collection/test/equality_test/04: Fail # Issue 1533
 collection/test/equality_test/05: Fail # Issue 1533
 collection/test/equality_test/none: Pass, Fail # Issue 14348
+docgen/test/multi_library_test: Slow, Pass # issue 17060
+shelf/test/message_test: RuntimeError # Issue 18109
 third_party/angular_tests/browser_test: Pass, Slow # Large dart2js compile time
 typed_data/test/typed_buffers_test/01: Fail # Not supporting Int64List, Uint64List.
-docgen/test/multi_library_test: Slow, Pass # issue 17060
 
 [ $compiler == dart2js && $checked ]
 crypto/test/base64_test: Slow, Pass