The element was renamed to dav1ddec in 0.9.0.
Pull request: https://github.com/WebKit/WebKit/pull/6206
Committed 256443@main (fb50a1fd7f85): <https://commits.webkit.org/256443@main> Reviewed commits have been landed. Closing PR #6206 and removing active labels.
<rdar://problem/102085188>