We don't implement :host-context.
<rdar://problem/114918695>
Pull request: https://github.com/WebKit/WebKit/pull/17399
Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/41790
Committed 267603@main (68e96f24aae9): <https://commits.webkit.org/267603@main> Reviewed commits have been landed. Closing PR #17399 and removing active labels.