Remove tool command.
Remove tool command.

It was initially added to support Go language tests. See
https://github.com/gopherjs/gopherjs/commit/da075debc443510928caee184375aa76898c6d38#commitcomment-17247656.

Remove it since it's no longer needed, and it's unlikely to be used.

Helps #388.

gopherjs/gopherjs,albrow/gopherjs,gopherjs/gopherjs,albrow/gopherjs,gopherjs/gopherjs,gopherjs/gopherjs,albrow/gopherjs,gopherjs/gopherjs