Automatic update from web-platform-tests [navigation-timing] Opt-in to single-page test feature (#19914) testharness.js was recently extended with an API to explicitly opt-in to the "single page test" feature [1]. As per WPT RFC 28 [2], tests which do not use this API and which do not declare any subtests will soon be reported as a harness error. Update the tests which previously opted in implicitly to use the new API. [1] https://github.com/web-platform-tests/wpt/pull/19449 [2] https://github.com/web-platform-tests/rfcs/blob/master/rfcs/single_test.md -- wpt-commits: a78dfab017b078a21b4a36520d92327d639a5c86 wpt-pr: 19914 Differential Revision: https://phabricator.services.mozilla.com/D53493
