Returns HTML for a marker for required form elements.
$variables: An associative array containing:
function theme_form_required_marker($variables) {
// This is also used in the installer, pre-database setup.
$t = get_t();
$attributes = array(
'class' => 'form-required',
'title' => $t('This field is required.'),
);
return '<abbr' . new Attribute($attributes) . '>*</abbr>';
}