<!DOCTYPE html>
<html>
<head>
    <script>
        if (window.testRunner)
            testRunner.waitUntilDone();

        function doTest()
        {
            requestAnimationFrame(() => {
                if (window.internals)
                    internals.setTopContentInset(50);

                requestAnimationFrame(() => {
                    if (window.internals)
                        internals.setTopContentInset(0);

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

        window.addEventListener('load', doTest, false);
    </script>
    <style>
        .box {
            width: 100px;
            height: 100px;
            background-color: blue;
        }
        
        .fixed {
            position: fixed;
            top: 0;
            left: 0;
        }
    </style>
</head>
<body>
    <div class="fixed box"></div>
</body>
</html>