lib_2/html/websql_test failure on Safari Mac

[jmesserly]

Two tests started failing in dart2js on Safari after this CL:
https://dart.googlesource.com/sdk/+/627e96c9c1d51f5762bed770e69ac694fce564ae

EDIT: looking now, I only see co19_2/LayoutTests/fast/mediastream/RTCPeerConnection-AddRemoveStream_t01 failure. The other one did not need to be approved. Perhaps it is flaky?

co19_2/LayoutTests/fast/mediastream/RTCPeerConnection-AddRemoveStream_t01: Timeout -> RuntimeError
lib_2/html/websql_test: Pass -> RuntimeError

The CL changed WebSQL test to use "package:expect/async_minitest.dart", which uses async_helper to ensure that the test does not report "pass" until all async tests are finished. So there was likely an issue that existed previously, but was not detected. I was not able to reproduce this when debugging, though--it seems to pass. It only fails when the full test is run with test.py. (Rerunning the repro steps described test.py does not show a failure.)

I tried changing the test to a more robust pattern for dart2js (which is not waiting for the Future returned by main(), unlike DDC browser tests that are waiting):

main() {
  asyncStart();
  setup().then((_) {
    runTests();
    asyncEnd();
  });
}

Unfortunately that didn't seem to make any difference.

It is worth noting that WebSQL is deprecated in favor of IndexedDB, and was not supported except for Chrome/Safari, so we may not want to invest much in this test.

[sigmundch]

Note: #46316