Land Big Sur-specific baselines for some WebSocket tests after 259006@main.
Pull request: https://github.com/WebKit/WebKit/pull/8840
Committed 259090@main (eb3ab881eb8e): <https://commits.webkit.org/259090@main> Reviewed commits have been landed. Closing PR #8840 and removing active labels.
<rdar://problem/104432020>