helper functions call undefined methods

[szepeviktor]

1. Plugin::the_performance_mark
2. Plugin::get_the_performance_mark

site-performance-tracker/php/helpers.php

Lines 16 to 18 in db1e669

	function the_site_performance_mark( $mark_slug ) {
	xwp_site_performance_tracker()->the_performance_mark( $mark_slug );
	}

Could helpers be deleted?