See https://ci.chromium.org/p/flutter/builders/prod/Windows%20web_tool_tests

In particular:

https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8843718898922094865/+/u/run_test.dart_for_web_tool_tests_shard_and_subshard_web/stdout?format=raw

It looks like this started happening with an Engine roll containing only a Fuchsia SDK roll, so it is probably unrelated.

/cc @yjbanov @shihaohong