Use `HashSet<CheckedRef<Range>>` instead of `WeakHashSet<Range>` for Document::m_ranges. The Range destructor takes care of removing itself from Document::m_ranges already so we don't need a WeakPtr. Using CheckedRef here is slightly more efficient.
Pull request: https://github.com/WebKit/WebKit/pull/18441
Committed 268680@main (cbb5cdba4811): <https://commits.webkit.org/268680@main> Reviewed commits have been landed. Closing PR #18441 and removing active labels.
<rdar://problem/116263456>