#import 
// https://html.spec.whatwg.org/#htmlorsvgelement
interface mixin HTMLOrSVGElement {
    [SameObject] readonly attribute DOMStringMap dataset;
    attribute DOMString nonce; // intentionally no [CEReactions]
    [CEReactions, Reflect] attribute boolean autofocus;
    [CEReactions] attribute long tabIndex;
    // FIXME: Support the optional FocusOptions parameter.
    undefined focus();
    undefined blur();
};