x/sort-by bug in CLJS

This only happens in **CLJS**

``` clojure
(= (sort-by identity > (shuffle (range 100)))
   (into [] (x/sort-by identity >) (shuffle (range 100))))

;; => false
```

Input is returned unchanged:

```clojure
(into [] (x/sort-by identity >) [3 2 0 4 8 5 6 7 1 9])
;; => [3 2 0 4 8 5 6 7 1 9]
```