Automatic update from web-platform-testsAdd tests for customElements.upgrade() (#9869) * Add tests for customElements.upgrade() Follows https://github.com/whatwg/html/pull/3535. * Fix one test; test that it's shadow-including descendants wpt-commits: e3b651475426769bba0f043fd53e11a9c4ef93d5 wpt-pr: 9869 wpt-commits: e3b651475426769bba0f043fd53e11a9c4ef93d5 wpt-pr: 9869