The method nsCoreUtils::IsXLink seems to treat an element as an XLink link only if xlink:type="simple" is present. If this code is for the old generic XLink support, the code is obsolete, because generic XLink support is gone. If this code is for SVG, it is incorrect, because SVG doesn't require xlink:type.
It is about XLink only. We use accessible of generic type for SVG, though we should be more diverse.
let's make sure to address xlink stuff for svg in bug 809744 and remove nsCoreUtils::IsXLink for now.
Created attachment 679541 [details] [diff] [review] patch