Resync html/semantics/forms/form-submission-0/implicit-submission.optional.html from upstream WPT.
Pull request: https://github.com/WebKit/WebKit/pull/3198
Committed 253309@main (37fdb87d9457): <https://commits.webkit.org/253309@main> Reviewed commits have been landed. Closing PR #3198 and removing active labels.
<rdar://problem/98476456>