Eldoc is missing for special forms

[bbatsov]

There's no eldoc for special forms like if, def and throw. Seems like some regression to me (or a glaring oversight if we never had it).

[bbatsov]

@jeffvalk do you recall if this ever worked? It might be just a figment of my imagination. Maybe we just never implemented it to begin with...

[jeffvalk]

@bbatsov I could be wrong, but I'm not sure this was ever there.