DEV: Have app/app export a class not an instance.

The app boot should call `create()`

app/assets/javascripts/app-boot.js

@@ -4,7 +4,7 @@
   if (window.unsupportedBrowser) {
     throw "Unsupported browser detected";
   }
-  let Discourse = requirejs("discourse/app").default;
+  let Discourse = requirejs("discourse/app").default.create();
 
   // required for our template compiler
   window.__DISCOURSE_RAW_TEMPLATES = requirejs(

app/assets/javascripts/discourse/app/app.js

@@ -179,6 +179,6 @@ const Discourse = Application.extend(FocusEvent, {
       return this.currentAssetVersion;
     }
   })
-}).create();
+});
 
 export default Discourse;