The DOM specs now use Document instead of HTMLDocument. http://www.whatwg.org/specs/web-apps/current-work/multipage/browsers.html#the-window-object http://dom.spec.whatwg.org/#domimplementation
A tiny nitpick: "For historical reasons, Window objects must also have a writable, configurable, non-enumerable property named HTMLDocument whose value is the Document interface object."
IE11 reversed their implementation to match WebKit/Firefox. I think we should update the spec instead.
Could you maybe email whatwg@whatwg.org with some more details? Or alternatively file a bug on the HTML specification.
@Anne - applicable anymore?
Yeah, let's close this for now. Once https://github.com/whatwg/dom/issues/221 gets resolved new bugs will be filed.