Bug 1771337 [wpt PR 34217] - Convert `popup=popup` to `popup=auto` or just `popup...

Bug 1771337 [wpt PR 34217] - Convert `popup=popup` to `popup=auto` or just `popup`, a=testonly

Automatic update from web-platform-tests
Convert `popup=popup` to `popup=auto` or just `popup`

Per the [1] resolution, `popup=popup` has been renamed to `popup=auto`.
Additionally, per the [2] resolution, "boolean-like" behavior is also
supported, such that `<div popup>` means the same thing as `<div popup=auto>`. This CL implements both of these changes.

Note that this CL has one case that still needs to be fixed:
  <div id=foo popup=invalid>
  <script>
    foo.popup === null; // false, should be true
  </script>

To fix the above, I need to figure out how to specify the ReflectMissing
and ReflectInvalid values so that they mean "null".

[1] https://github.com/openui/open-ui/issues/491#issuecomment-1132165724
[2] https://github.com/openui/open-ui/issues/533#issuecomment-1138874090

Bug: 1307772
Change-Id: I6037c5322f7408ebd2c91690f89ecbc513c66bdb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3668816
Auto-Submit: Mason Freed <masonf@chromium.org>
Commit-Queue: Mason Freed <masonf@chromium.org>
Reviewed-by: Joey Arhar <jarhar@chromium.org>
Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1009383}

--

wpt-commits: 71cf6a42d3335c0c55cfe5b18c3b250c21a0ffbc
wpt-pr: 34217