`inherit gradientElement`
`method cx : animatedLength Js_of_ocaml__.Js.t Js_of_ocaml__.Js.readonly_prop`
`method cy : animatedLength Js_of_ocaml__.Js.t Js_of_ocaml__.Js.readonly_prop`
`method r : animatedLength Js_of_ocaml__.Js.t Js_of_ocaml__.Js.readonly_prop`
`method fx : animatedLength Js_of_ocaml__.Js.t Js_of_ocaml__.Js.readonly_prop`
`method fy : animatedLength Js_of_ocaml__.Js.t Js_of_ocaml__.Js.readonly_prop`
`method fr : animatedLength Js_of_ocaml__.Js.t Js_of_ocaml__.Js.readonly_prop`

SVG 2 addition (focal radius).