// https://drafts.fxtf.org/css-masking/#InterfaceSVGMaskElement
[Exposed=Window]
interface SVGMaskElement : SVGElement {
    [FIXME] readonly attribute SVGAnimatedEnumeration maskUnits;
    [FIXME] readonly attribute SVGAnimatedEnumeration maskContentUnits;
    [FIXME] readonly attribute SVGAnimatedLength x;
    [FIXME] readonly attribute SVGAnimatedLength y;
    [FIXME] readonly attribute SVGAnimatedLength width;
    [FIXME] readonly attribute SVGAnimatedLength height;
};