Merge pull request #2728 from jchavarri/console-utils

Add console.error and console.trace

Author: bobzhang

jscomp/others/js_console.ml

@@ -1,6 +1,6 @@
-
-
+external error : 'a -> unit = "" [@@bs.val] [@@bs.scope "console"]
 external log : 'a -> unit = ""  [@@bs.val] [@@bs.scope "console"]
+external trace : unit -> unit = "" [@@bs.val] [@@bs.scope "console"]
 external warn : 'a -> unit = "" [@@bs.val] [@@bs.scope "console"]
 
 external timeStart : string -> unit =