<!DOCTYPE html>
<style>
    ruby::after {
        display: block;
        content: "";
    }
    ruby {
        display: block;
    }
</style>

<script>
if (window.testRunner)
    testRunner.dumpAsText();

onload = function() {
    var ruby = document.createElement('ruby');
    document.body.appendChild(ruby);
    document.body.offsetTop;
    ruby.appendChild(document.createTextNode('Passed if this test did not crash or assert.'));
}
</script>