0a2c58e51c
These were lost in 35b560e289 and could result in an unhandled error when there's a race during shutdown if a request had been trying to resume an isolate.
Fixes https://github.com/flutter/flutter/issues/139181
Change-Id: Ie683f5afa801e8d05e15d93a0e2008cd0f74fe5d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/344521
Reviewed-by: Helin Shiah <helinx@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>