[css-lists] Opt-in to single-page test feature (#20167)
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 a test 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
diff --git a/css/css-lists/list-inside-contain.html b/css/css-lists/list-inside-contain.html
index dc06eab..70e25b8 100644
--- a/css/css-lists/list-inside-contain.html
+++ b/css/css-lists/list-inside-contain.html
@@ -14,6 +14,8 @@
</head>
<script>
+setup({ single_test: true });
+
function changeBackground() {
document.getElementById("target").style.setProperty("background", "url(data:image/gif;base64,R0lGODlhEAAQAMQAAORHHOVSKudfOulrSOp3WOyDZu6QdvCchPGolfO0o/XBs/fNwfjZ0frl3/zy7////wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACH5BAkAABAALAAAAAAQABAAAAVVICSOZGlCQAosJ6mu7fiyZeKqNKToQGDsM8hBADgUXoGAiqhSvp5QAnQKGIgUhwFUYLCVDFCrKUE1lBavAViFIDlTImbKC5Gm2hB0SlBCBMQiB0UjIQA7) no-repeat scroll top right");
