Fix appearance-cssom-001.html.

* Remove some legacy appearance aliases that other engines don't
   implement.

 * Allow to pass with unimplemented <compat-auto> values, since per the
   spec the idea of these is to get them removed, see
   w3c/csswg-drafts#8506 for the ones we don't
   implement.

 * Also allow the `-moz-` prefix to be implemented, because we can't
   quite get rid of it (people use it to remove the <input type=number>
   buttons with -moz-appearance: textfield and so on), and the
   alternative is to implement a bunch of non-standard ::-webkit-
   pseudo-elements.

Differential Revision: https://phabricator.services.mozilla.com/D171243

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1695565
gecko-commit: e3553560e147b892fedd78a1e722a84f17f08b65
gecko-reviewers: boris