src/vs/css.ts/createLinkTag
function createLinkTag(name: string, cssUrl: string, callback: () => void, errorback: (err: any) => void): void {
	const linkNode = document.createElement('link');
	linkNode.setAttribute('rel', 'stylesheet');
	linkNode.setAttribute('type', 'text/css');
	linkNode.setAttribute('data-name', name);

	attachListeners(name, linkNode, callback, errorback);
	linkNode.setAttribute('href', cssUrl);

	const head = document.head || document.getElementsByTagName('head')[0];
	head.appendChild(linkNode);
}