LayoutTests/fast/animation/request-animation-frame-callback-id.html

<script>
if (window.testRunner) {
    window.testRunner.dumpAsText();
    window.testRunner.waitUntilDone();
}

function runTest() {
    var id = window.requestAnimationFrame(function () {});
    var results = document.getElementById("results");

    if (id > 0)
        results.innerText = "PASSED: Callback id was > 0";
    else
        results.innerText = "FAILED: Callback id was <= 0";

    if (window.testRunner)
        window.testRunner.notifyDone();
}

window.addEventListener("load", runTest, false);
</script>
<div id="results"></div>