Work towards https://github.com/dart-lang/sdk/issues/60635

Change-Id: Ieea525a3f7260ea50e766feff0a0647fc0c33b4d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/434526


Commit-Queue: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>