In SVG2, hasFeature always return true. So requiredFeatures attribute not doing anything useful. It has been removed from the spec: https://github.com/w3c/svgwg/commit/9a30d01f6410dc516c5f874d71e957230a3448cd This was deprecated in Chrome 54/Opera 41.
Docs: https://developer.mozilla.org/en-US/docs/Web/API/SVGTests