Hide documentation of rand_wasm_bindgen_test crate

[vks]

Fixes #913.

[dhardy]

Hmm:

 Documenting rand_wasm_bindgen_test v0.1.0 (/home/travis/build/rust-random/rand/tests/wasm_bindgen)

error: couldn't generate documentation: No such file or directory (os error 2)

[dhardy]

I guess this is a side-effect of using --all in

cargo doc --no-deps --all --all-features

It is possible to list crates manually (-p rand -p rand_core ...) but I'm not keen on this. Perhaps we should just put up with the status quo?

[vks]

Some alternatives to try are #![doc(html_no_source)] and #[doc(masked)] (unstable).

[dhardy]

I tried both locally; in each case the documentation was still generated (no apparent effect). (Using #![doc(hidden)] locally also failed the bulid.)

[vks]

I guess that means the only remaining option is to list the crates individually.

[vks]

I'm closing this, since it seems like we cannot fix this by changing the source.