Cleaned up some stuff in refreshless_turbo/js/progress_bar.js:

Mostly removed a commented out console.debug() and converted a handler
to arrow function.

modules/refreshless_turbo/js/progress_bar.js

@@ -20,9 +20,7 @@
   // Note that this intentionally listens to the fetch request event rather than
   // turbo:click so that the progress bar also kicks in during back/forward
   // history navigation.
-  html.addEventListener('turbo:before-fetch-request', function(event) {
-
-    // console.debug(event.target);
+  html.addEventListener('turbo:before-fetch-request', (event) => {
 
     if (
       // Ignore prefetch requests.