SWServerWorker::didFinishActivation is sometimes called on workers that are not in activating state
<rdar://110529723>
Pull request: https://github.com/WebKit/WebKit/pull/14920
Committed 265121@main (fb46eb89ed57): <https://commits.webkit.org/265121@main> Reviewed commits have been landed. Closing PR #14920 and removing active labels.