We had to do a similar polyfill for i18n/wp code is like
if ( ! wp_script_is( 'wp-i18n', 'registered' ) ) {
wp_enqueue_script( 'fl-wp-i18n', "{$js_vendors}i18n-polyfill.js" );
}
and the js file is simply
window.wp = window.wp || {};
window.wp.i18n = {};