ES6 spec-compliant RegExp.prototype.flags shim.
An ES2015 spec-compliant `Function.prototype.name` shim
An ES2019 spec-compliant `Array.prototype.flat` shim/polyfill/replacement that works as far down as ES3.
ES2019 spec-compliant String.prototype.trimEnd shim.
ES2019 spec-compliant String.prototype.trimStart shim.