GitLab

crostini: Use test_util.flushTasks instead of our own version

We currently wait for polymer updates by flushing then by continuing
after Polymer.async. This doesn't actually wait for everything, since
it's a Polymer microtask, so it preempts macrotasks and will run before
nested microtasks (e.g. a Polymer update triggers an attached event
which kicks off its own promise, we'd run between the attached event and
the promise). Instead use test_util.flushTasks which has macrotask
timing.

Test: browser tests
Bug: chromium:1082027
Change-Id: I5d35b0c61570913d7a36e89600dce597703c2aad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2263634Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: David Munro <davidmunro@google.com>
Cr-Commit-Position: refs/heads/master@{#782123}