Simplify ActionCable.createConsumer by using default argument

actioncable/app/assets/javascripts/action_cable.js

@@ -452,11 +452,8 @@
     };
     return Consumer;
   }();
-  function createConsumer(url) {
-    if (url == null) {
-      var urlConfig = getConfig("url");
-      url = urlConfig ? urlConfig : INTERNAL.default_mount_path;
-    }
+  function createConsumer() {
+    var url = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : getConfig("url") || INTERNAL.default_mount_path;
     return new Consumer(createWebSocketURL(url));
   }
   function getConfig(name) {

actioncable/app/javascript/action_cable/index.js

@@ -18,11 +18,7 @@ export {
   logger,
 }
 
-export function createConsumer(url) {
-  if (url == null) {
-    const urlConfig = getConfig("url")
-    url = (urlConfig ? urlConfig : INTERNAL.default_mount_path)
-  }
+export function createConsumer(url = getConfig("url") || INTERNAL.default_mount_path) {
   return new Consumer(createWebSocketURL(url))
 }