Fix tests: window.onload = setTimeout.

This is similar to a previous CL:
https://chromium-review.googlesource.com/c/chromium/src/+/1051908

All of these tests are using:
window.onload = setTimeout([...], 0);
The issue is that setTimeout is executed immediately instead of on load.

Bug: 831155
Change-Id: I913b8c04de5d583ef87c91dfc23d4ba8be8ba642
Reviewed-on: https://chromium-review.googlesource.com/1055391
Reviewed-by: Nate Chapin <japhet@chromium.org>
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558229}
5 files changed