<!DOCTYPE html>
<body>
<style>
    div {
        position: absolute;
        height: 100px;
        top: 0;
    }
</style>
<div id="target" style="left: 0; width: 1px; background-color: red;"></div>
<div style="left: 1px; width: 798px; background-color: black;"></div>
<script>

if (window.testRunner)
    testRunner.waitUntilDone();

const target = document.getElementById("target");
target.style.transform = "translateX(799px)";
setTimeout(() => {
    target.style.removeProperty("transform");
    target.style.transition = "transform 10s linear";
    setTimeout(() => {
        if (window.testRunner)
            testRunner.notifyDone();
    }, 100);
});

</script>
</body>