Bug 1880577 [wpt PR 44621] - Make dir=auto elements without strong characters ltr...

Bug 1880577 [wpt PR 44621] - Make dir=auto elements without strong characters ltr (rather than inheriting)., a=testonly

Automatic update from web-platform-tests
Make dir=auto elements without strong characters ltr (rather than inheriting).

This reverts (conditioned on a new DirAutoNoInheritance flag) a previous
change from https://crrev.com/c4557b863d101826932f33757e9398e7fca056c9
and makes it so that dir=auto elements never inherit directionality from
their parent.  Instead, when no strong characters are present, they have
LTR directionality, as we did before.

Reverting to our old behavior (and reverting the relevant test to its
old state) seems like the best option given the discussion in
https://github.com/whatwg/html/issues/10097 .

Once this ships to stable we can remove the mechanisms used to support
that inheritance.

The changes in html/dom/elements/global-attributes/dir_auto-N-EN.html
and its reference are a direct revert of the prior test change in the CL
above.

The changes in bdi-auto-dir-default.html and
bdi-dir-default-to-auto.html are reverting a newer test change from
https://crrev.com/4278cdb00ac4e727c1123e5eb4aba86509e87c0b .

The new dir-shadow-42 test is a version of dir-shadow-41 with the
directions swapped, to make sure things are tested more thoroughly.

Fixed: 41494751
Bug: 576815
Change-Id: I68b36a1fc19a0553f582fdf2fd02a94d6e633686
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5302287
Commit-Queue: David Baron <dbaron@chromium.org>
Commit-Queue: Di Zhang <dizhangg@chromium.org>
Auto-Submit: David Baron <dbaron@chromium.org>
Reviewed-by: Di Zhang <dizhangg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1261442}

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wpt-commits: 9630591d607ac18d6572602cf0f1ba5129fe9954
wpt-pr: 44621