<html class="reftest-wait">
    <head>
        <script>
            function showItem() {
                var el = document.getElementById("two");
                getComputedStyle(el).opacity; // flush styles
                el.style.opacity = 1;
                document.documentElement.removeAttribute("class");
            }
            window.addEventListener("MozReftestInvalidate", showItem, false);
        </script>
    </head>
    <body>
        <div id="one" style="width:50px; height:50px; background-color:blue; position:absolute"></div>
        <div id="two" style="width:500px; height:500px; background-color:red; opacity:0.99"></div>
    </body>
</html>