If on the root SVG element requiredFeatures or any of the other test attributes is set, they are not taken into account. I checked in FF and Opera and there they are taken into account.
Created attachment 31266 [details] First attempt
Comment on attachment 31266 [details] First attempt Ouch, good catch! r=me.
Thanks! Landed in r44808.
This kind of virtual function override in a leaf class should normally be private rather than public.