Build speed improvement

[cecton]

When I see how fast is the WASM compiled I wonder if we could not bypass the wasm-bindgen build entirely.

The current process to build is as follow:

1. run pre-build
2. run cargo build --target wasm...
3. run wasm-bindgen to generate the JS and stuff that wraps the wasm
4. run post-build

I believe the really slow stuff is actually in the point 3 with wasm-bindgen. Maybe it is possible to run it once and then re-use the existing JS code and stuff.

This is an idea and it should be explored. It doesn't mean it is true or can be done.