Throw when constructing a SharedWorker in a detached document, to match other browsers.
<rdar://110231627>
Pull request: https://github.com/WebKit/WebKit/pull/15260
Committed 265483@main (677b4473a8cb): <https://commits.webkit.org/265483@main> Reviewed commits have been landed. Closing PR #15260 and removing active labels.