IOFactory protocol extension on String does not call its Coercions

The IOFactory protocol extension on [String|(https://github.com/clojure/clojure/blob/master/src/clj/clojure/java/io.clj#L251] doesn't call the respective as-file and as-url implemented in Coercions.

I found it odd and fixed it. If it had been done on purpose, I apologize.