[whatwg] Why are we merging Document and HTMLDocument again?

[Cameron McCormack]

Dirk Schulze wrote:
> We can not eliminate SVGDocument until you want to have SVG specific
> attributes on Document ;). This was  not the discussion on the SVG
> WG. But we do want to share all methods with HTMLDocument where is
> makes sense, which are most of them. HTMLDocument, as noted by Boris,
> have specific methods as well that we do not necessarily want in a
> general scoped Document object.

We did discuss and agree to this last year:

   http://www.w3.org/2012/09/19-svg-minutes.html#item04

and Erik made the change shortly afterwards.

   https://svgwg.org/svg2-draft/struct.html#InterfaceSVGDocument

The only "interesting" attribute there is rootElement.  And that isn't 
particularly interesting, though people do use it, so we can't get rid 
of it.

I don't think there's any real downside to having rootElement exist on 
all Document objects.