Help to compile a wasm package

[Yadd <yadd@debian.org>]

Hi all,

to update a nodejs package, I need to build a wasm file using cargo. I 
succeed to do it but it downloads some package during build process:
 * libc-0.2.116
 * rand-0.4.6
 * vlq-0.5.1

Which package do I have to install as dependency to avoid this ?

Cheers,
Yadd

PS: sorry, I don't know anything about rust packaging, neither 
rust/cargo themselves...