cleanup: Use rest parameters instead of arguments

Spotted by eslint.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/607

js/ui/environment.js

@@ -57,8 +57,8 @@ function _patchLayoutClass(layoutClass, styleProps) {
     };
 }
 
-function _loggingFunc() {
-    let fields = {'MESSAGE': [].join.call(arguments, ', ')};
+function _loggingFunc(...args) {
+    let fields = {'MESSAGE': args.join(', ')};
     let domain = "GNOME Shell";
 
     // If the caller is an extension, add it as metadata