chromium/third_party/blink/web_tests/shadow-dom/css-cascade-outer-scope2.html

<!DOCTYPE html>
<style>.t { color: green }</style>
<div id="host">
    <span id="t" class="t">This text should be green.</span>
</div>
<script>
if (window.testRunner)
    testRunner.dumpAsText();

var root = host.attachShadow({'mode': 'open'});
root.innerHTML = '<style>::slotted(*) { color: red }</style><slot></slot>';
document.write(getComputedStyle(t).color == 'rgb(0, 128, 0)' ? 'PASS' : 'FAIL');
</script>