chromium/third_party/blink/web_tests/paint/invalidation/outline/focus-layers.html

<html>
<head>
<style type="text/css">
a {
    border: 2px solid red;
    position: relative;
}
a span.relative {
    border: 2px solid blue;
    white-space: nowrap;
    position: relative;
    top: 10em;
}
a span.absolute {
    border: 2px solid green;
    white-space: nowrap;
    position: absolute;
    top: 12em;
}
</style>

</head>
<body>
<div>

Both <a href="#" id="link">this and <span class="relative">this should have correctly placed focus rings</span> <span class = "absolute">but not this</span>.</a>
</div>

<script>
document.getElementById('link').focus();
</script>
</body>
</html>