Sync web-platform-tests PR 34548 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/34548
Details from upstream follow.

Pâris Meuleman <pmeuleman@chromium.org> wrote:

Fix Sandbox WPT using a non-existing file

Another file that was using ./common/blank.html instead of an existing
file. I also propose a fix for firefox behavior where it might not throw
if the origin is checked synchronously, this by adding a timeout and
trying again.

Change-Id: I2ce8277d09d03b4be575315b0828a4a279dd7337
Reviewed-on: https://chromium-review.googlesource.com/3720219
WPT-Export-Revision: ab7ef45395089d308b5c986e556563b00b06db38

CI Results

Ran 9 Firefox configurations based on mozilla-central, and Firefox, Chrome, and Safari on GitHub CI

Total 1 tests and 1 subtests

Status Summary

Firefox

OK : 1
PASS: 1

Chrome

OK : 1
PASS: 1

Safari

OK : 1
PASS: 1

Links

Gecko CI (Treeherder)
GitHub PR Head
GitHub PR Base

https://hg.mozilla.org/mozilla-central/rev/ed1feaf27ec1