polyfill-service/polyfills/Element/prototype/before/polyfill.js

A polyfill combinator

Document.prototype.before = Element.prototype.before = function before() {
	if (this.parentNode) {
		this.parentNode.insertBefore(_mutation(arguments), this);
	}
};

// Not all UAs support the Text constructor.  Polyfill on the Text constructor only where it exists
// TODO: Add a polyfill for the Text constructor, and make it a dependency of this polyfill.
if ("Text" in this) {
	Text.prototype.before = Element.prototype.before;
}