[whatwg] classList should perhaps move from HTMLElement to Element

[Cameron McCormack]

Rik Cabanier:
> There was a discussion in the SVG WG about dropping the
> SVGAnimatedxxx objects and have replace them with regular values. We
> would need some tricks so we can change the DOM, but make it
> backward compatible at the same time.

We have discussed this a few times, and I would desparately love for it
to work, but I am unconvinced it will.  I can an imagine an author
writing code like:

   if (!elt.className) ...

to test if a class has been set.  Even if we made the
SVGElement.className SVGAnimatedString object one that stringifies to
the class, add a [PutForwards] on to it so that assigning a string
works, it would still break the above code, since the ! operator always
returns false for an object.