The module/nomodule tests are the most flaky ones, contributing significantly
to increase number of test failures (somewhat mitigated by auto-retries).

Fix flakiness of module/nomodule tests:
1. For module tests, increase the timeout to 5 seconds. In order for most tests
   to not wait that long, change callbacks called by module scripts to verify
   the results as soon as all scripts have run.
2. For nomodule tests, run the check in 1 second. All modern browsers will
   need to wait that long, hence a smaller timeout, and if occasionally the
   check runs too quickly, the test will still pass.

Closes gh-5699

(cherry picked from commit 5964acf)

In IE, these tests are expected to be executed, so the timeout can be higher,
similar to how we set a high timeout for module tests.

Ref gh-5699