Allowing style tag in TinyMCE editor

There are some things to try in this stackoverflow thread. The one I’m trying:

add_filter('tiny_mce_before_init', 'vsl2014_filter_tiny_mce_before_init');
function vsl2014_filter_tiny_mce_before_init( $options ) {

    if ( ! isset( $options['extended_valid_elements'] ) ) {
        $options['extended_valid_elements'] = 'style';
    } else {
        $options['extended_valid_elements'] .= ',style';
    }

    if ( ! isset( $options['valid_children'] ) ) {
        $options['valid_children'] = '+body[style]';
    } else {
        $options['valid_children'] .= ',+body[style]';
    }

    if ( ! isset( $options['custom_elements'] ) ) {
        $options['custom_elements'] = 'style';
    } else {
        $options['custom_elements'] .= ',style';
    }

    return $options;
}