[JS] invalid JS syntax emitted when negating negative literals in computational expression

[goswinr]

It took me a while to track this down.
I got an Invalid left-hand side expression in prefix operation exception from my JS entry file, not the actual location of the problem.

It comes down to this:
In computational expressions, the float literal gets inlined and the negate sign is added twice

let f x  = x

[
  let x = -5.0  
  f (-x) 
]
|> ignore

This emits --5 , which is invalid JS.

see REPL