chromium/third_party/blink/web_tests/fast/css/last-child-style-sharing.html

<html>
    <head>
        <style type="text/css">
            div {
                background-color: red;
                width: 100px;
                height: 100px;
            }

            div:last-child {
                position: relative;
                top: -100px;
                background-color: green;
            }
        </style>
    </head>
    <body>
        <div></div>
        <div></div>
    </body>
</html>