rustdoc: Wrong page suggestion on search

[klutzy]

Searching insert on rustdoc leads here (broken link) rather than here.

Same for searching zip. (the suggested link)

[huonw]

gen does a similar thing: http://static.rust-lang.org/doc/master/std/rand/Rng/trait.Rng.html

It appears to be a problem with default methods.

[alexcrichton]

cc me