This ControlPart will handle drawing the checkbox and the radio buttons form controls.
<rdar://problem/103548470>
Pull request: https://github.com/WebKit/WebKit/pull/7903
Committed 258177@main (a5f12d1b9232): <https://commits.webkit.org/258177@main> Reviewed commits have been landed. Closing PR #7903 and removing active labels.