Use `drain` to reach end of stream in tests (dart-lang/web_socket_channel#75)

Replace `.toList()` for cases where we don't care about the collected
values.

Replace `.listen(null).asFuture()` since that is exactly the
implementation of `drain`.
1 file changed
tree: 90bc7783dd378b537dfc98873de38844afca9539
  1. pkgs/