wait_200_milliseconds sometimes fails.

[jrmuizel]

wait_200_milliseconds, elapsed: 0.3790910243988037
thread 'runloop::test::wait_200_milliseconds' panicked at 'assertion failed: elapsed > 0.19 && elapsed < 0.30', core-foundation/src/runloop.rs:184:9
note: Run with `RUST_BACKTRACE=1` for a backtrace.
test runloop::test::wait_200_milliseconds ... FAILED
failures:
failures:
    runloop::test::wait_200_milliseconds

We should make it more reliable.