The portals repo was written with ancient browsers like IE6 in mind, and therefore still ships with ancient polyfills for ES5 features. Since browsers lower than IE9 cannot even access Wikimedia sites due to TSL 1.2 limitations, many polyfills from this file https://gerrit.wikimedia.org/r/plugins/gitiles/wikimedia/portals/+/refs/heads/master/dev/wikipedia.org/assets/js/polyfills.js should be removed.
Remove the following methods from the polyfills.js file.
This file currently has features a global /* eslint-disable */ at the top. This comment can also be removed so the file may be properly formatted.