Returns HTML for a number form element.
$variables: An associative array containing:
function theme_number($variables) {
$element = $variables['element'];
$element['#attributes']['type'] = 'number';
element_set_attributes($element, array(
'id',
'name',
'value',
'step',
'min',
'max',
'placeholder',
));
_form_set_attributes($element, array(
'form-number',
));
$output = '<input' . new Attribute($element['#attributes']) . ' />';
return $output;
}