Web REPL cleanups

[brian-carroll]

• Change the height of the loading message to match the loaded state (screenshots below)
• Make JS code clearer
• Remove wasi.js since we never use it
  • There is no way for the user's Roc program to make system calls. The platform we use for the REPL has no effects.
  • When I wrote this originally I don't think I fully understood platforms and effects and stuff. (And gen_wasm was actually generating with WASI imports because I hadn't figured out how to eliminate them.)
  • If we ever support dbg we might need to bring back WASI? There are other ways of implementing it.

Previous loading state

Darker than normal because I paused JS at a breakpoint to take the screenshot

New loading state

Darker than normal because I paused JS at a breakpoint to take the screenshot

Loaded state

[rtfeldman]

If we ever support dbg we might need to bring back WASI? There are other ways of implementing it.

I think we should be able to do this using the same way we do roc_alloc, except have it call console.log - so, still shouldn't require wasi!

[rtfeldman]

Lovely, thanks @brian-carroll! 🎉

[brian-carroll]

Oh wow, this is wrong. This field was changed to a number everywhere else.
The initial value always get overwritten, so everything works. But it's confusing.
I'll make another PR.