GitLab

This CL does the following fixes to crossiframe.html test:
* Remove slow-image and onload, which are obsolete assumptions.
Instead, rely solely on PerformanceObserver.
* Use awaits where needed to make the test logic more sequential.
* Use coordinates and test_driver.Actions() to target the iframe. Using
the test_driver.click directly won't work for elements in iframes.
* Updates the test to check reasonable values for the frame and iframe
entries and check that they don't receive each other's entries.

This CL also:
* Removes unneeded variables from the clickAndBlockMain().
* Removes manual test, which is no longer needed.

Bug: 831729
Change-Id: Iff50035a216b21f67cd71796023af4f934573086
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1972249
Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
Reviewed-by: Annie Sullivan <sullivan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726422}