Fix a bug in test_driver.bless()

[chromium-wpt-export-bot]

This code was previously doing this:

let wait_click = new Promise(resolve => {
button.addEventListener("click", resolve));
};
return test_driver.click(button)
.then(wait_click)
.then(...

but the argument to .then(wait_click) isn't a function, it's the
promise to return. Therefore .then() creates an already-resolved
promise containing wait_click as its resolved value. Which the next
.then() block ignores. So this wasn't actually waiting for the click
to occur.

This triggered a number of test bugs (caused by erroneous assumptions
accidentally baked into the tests. I fixed a few, and filed a few
bugs for the rest (after failing to figure out how to fix them).

Note that the WPT version of testdriver.js is rolled into Chromium,
so that change is being made here:
#49691

Bug: 384009734,384050894
Change-Id: Ibdb8a97d23998ad89c5a48c23a7e780dc605283b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6094526
Reviewed-by: Jonathan Lee <jonathanjlee@google.com>
Auto-Submit: Mason Freed <masonf@chromium.org>
Commit-Queue: Mason Freed <masonf@chromium.org>
Commit-Queue: Jonathan Lee <jonathanjlee@google.com>
Cr-Commit-Position: refs/heads/main@{#1397010}

[wpt-pr-bot]

The review process for this patch is being conducted in the Chromium project.

[past]

@mfreed7 are the Safari test failures expected?

[mfreed7]

@mfreed7 are the Safari test failures expected?

Interesting. So two things changed in this PR, one is the change to test_driver and the other was a cleanup of the one failing Safari test. The failure there doesn't appear related to the test_driver change. It would seem that perhaps there's a bug in Safari with user activation and showPicker()? The only real change for all of the newly-failing tests is that the test now (correctly) adds the element to the document before calling showPicker(). I'm up for comments on what I changed in the test, but it looks "ok" to me.

[past]

Looks good to me too.

[past]

The new failures seem like legitimate bugs, so I will merge this.