chromium/third_party/blink/web_tests/fast/css/nth-child-no-mutations.html

<!DOCTYPE html>
<script src="../../resources/js-test.js"></script>
<style>
    #test :nth-child(odd) { color: green; }
    #test :not(.a) { color: rgb(200, 200, 200); }
</style>
<div id="test">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
</div>
<script>
description("Not necessary to recalc sibling styles for :nth-child when no mutations have happened.");

document.body.offsetTop;

var testElm = document.querySelector("#test div");
testElm.className = "a";

if (window.internals)
    shouldBe("internals.updateStyleAndReturnAffectedElementCount()", "1");

var green = "rgb(0, 128, 0)";
shouldBe("getComputedStyle(testElm, null).color", "green");
</script>