Directions provided by Paul (@stereotype441 )-- Found a repro, at least on my machine. I've uploaded the state of my code to https://dart-review.googlesource.com/c/sdk/+/111671 and included repro instructions in the CL description. You should be able to download the exact state of the code that I was using by clicking "download" and using the command line listed under "checkout". Let me know if you have any trouble reproducing it.

See the directions in https://dart-review.googlesource.com/c/sdk/+/111671

I was able to reproduce the issue on the bleeding edge of the master branch of the dart-sdk (a locally built 2.5.0), but not on 2.4.0, downloaded from https://dart.dev/tools/sdk/archive