Updated the test so that it uses assertPromiseResult, which makes sure that
a promise rejection is not swallowed. The change is reflected in the actual
async ids, checked in the test.

Bug: v8:8300
Change-Id: Ie227ca74a8cf4e0e079809b21c3abc5a5f87c11a
Reviewed-on: https://chromium-review.googlesource.com/c/1278388
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56608}