1861778 - Remove waitForMultiple test helper in dom/workers/test/dom_worker_helper.js in favor of Promise.all or sequential awaits

Status: NEW

(Core :: DOM: Workers, task, P3)

Description

[Andrew Sutherland [:asuth] (he/him)]

Assuming my test changes in https://phabricator.services.mozilla.com/D191822 for bug 1828084 land and stick, we should remove the waitForMultiple helper in https://searchfox.org/mozilla-central/source/dom/workers/test/dom_worker_helper.js entirely in favor of some combination of

• using Promise.all() for multiple promises where we don't really care about their ordering
• using a more explicit idiom for waiting in sequence that's explicit with actual comments explaining why an ordering invariant is guaranteed/required.

See the PR for more context.