Re: "var" declarations shadowing properties from Window.prototype

Brendan Eich:
> As noted, they started out that way 17 years ago. I think WebIDL and
> interface-based method definition made onload, e.g., predefined on
> window objects, or more recently on Window.prototype. Was this useful?
> Was it intended specifically (for window, not just intended generally
> due to WebIDL's uniform rules for binding its definitions in JS)?

I don't think it provides any benefit.  Uniformity is the only reason 
the spec says they should be there, currently.