[gardening] Mark test as flaky in dartkb mode

Issue: https://github.com/dart-lang/sdk/issues/35590
Change-Id: I95721a0a62a1e6201ffd4f7833eed089f915c2e5
Reviewed-on: https://dart-review.googlesource.com/c/88660
Auto-Submit: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
diff --git a/tests/lib_2/lib_2_kernel.status b/tests/lib_2/lib_2_kernel.status
index ca19533..b5f6efc 100644
--- a/tests/lib_2/lib_2_kernel.status
+++ b/tests/lib_2/lib_2_kernel.status
@@ -81,6 +81,7 @@
 [ $compiler == dartkb && $strong ]
 convert/streamed_conversion_json_utf8_decode_test: Pass, Timeout # Please triage.
 isolate/isolate_complex_messages_test: Pass, Crash # runtime/vm/object.cc: 17395: error: expected: type_arguments.IsNull() || type_arguments.IsCanonical()
+isolate/kill_regexp_test: Pass, Crash # Issue 35590 - isolate.cc: 2863: error: expected: sticky_error_ == Error::null()
 isolate/mandel_isolate_test: Pass, Timeout # Please triage.
 isolate/spawn_uri_exported_main_test: Pass, RuntimeError # Please triage: Expect.fail('Isolate was not spawned successfully.')
 mirrors/invocation_fuzz_test/emptyarray: Skip # Times out, issue 32232