<!DOCTYPE html>
<!-- form with one valid element which is made valid dynamically -->
<html>
<head>
<style>
form:invalid {display: none;}
</style>
</head>
<script>
function onloadHandler()
{
document.getElementById('i').value = 'foo';
document.documentElement.className = '';
}
</script>
<body onload="onloadHandler();">
<form>
<input id='i' required>
</form>
</body>
</html>