Eliminate a superfluous List.reverse call in Random.list

[jvoigtlaender]

Replaces https://github.com/elm-lang/core/pull/522, which became collateral damage in the branch killing spree.

Why remove that List.reverse call? Without it, generation is more efficient. And its presence or absence doesn't carry meaning for the semantics of randomness.

An argument has been made in the other discussion that with that call one has some sort of stability. But I have pointed out that it's a very fragile stability, and might even be harmful in terms of raising expectations, and in any case isn't compositional.

In this:

import Random
import Html

seed =
  Random.initialSeed 314159

triple n =
  let list = Random.list n (Random.int 0 100)
      gen = Random.map3 (,,) list Random.bool list
  in Random.step gen seed |> fst

main =
  Html.text <| toString (triple 2) ++ " " ++ toString (triple 5)

the outputs are ([2,22],True,[50,42]) vs. ([2,22,89,50,42],False,[47,79,82,79,6]). So only an appearance of stability.

[evancz]

Added to #724

[evancz]

Added to #724