Fix dartium test expectations

Fallout from initializing formal access change.

BUG=
R=whesse@google.com

Review URL: https://codereview.chromium.org/2535083002 .
diff --git a/tests/lib/lib.status b/tests/lib/lib.status
index 0f21a8c..2a84f7b 100644
--- a/tests/lib/lib.status
+++ b/tests/lib/lib.status
@@ -269,6 +269,7 @@
 mirrors/mirrors_used*: SkipByDesign # Invalid tests. MirrorsUsed does not have a specification, and dart:mirrors is not required to hide declarations that are not covered by any MirrorsUsed annotation.
 
 [ $compiler == none && ($runtime == drt || $runtime == dartium) ]
+mirrors/initializing_formals_test/01: Fail # initializing formals are implicitly final as of Dart 1.21
 async/schedule_microtask6_test: Fail # Issue 10910
 async/timer_test: Fail, Pass # Issue 15487
 async/multiple_timer_test: Fail, Pass # Issue 15487