Implement the spec change in the commit at https://github.com/whatwg/html/pull/9400/commits/b945c9c, which https://github.com/openui/open-ui/issues/786#issuecomment-1710709737 explains in detail.
Pull request: https://github.com/WebKit/WebKit/pull/18281
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Committed 269127@main (672fe76f3677): <https://commits.webkit.org/269127@main> Reviewed commits have been landed. Closing PR #18281 and removing active labels.