DEV: Convert to native class syntax (#110)

assets/javascripts/discourse/adapters/user-note.js

@@ -1,9 +1,9 @@
 import RestAdapter from "discourse/adapters/rest";
 import { ajax } from "discourse/lib/ajax";
 
-export default RestAdapter.extend({
+export default class UserNote extends RestAdapter {
   destroyRecord(store, type, record) {
     const path = this.pathFor(store, type, record.id);
     return ajax(`${path}?user_id=${record.user_id}`, { method: "DELETE" });
-  },
-});
+  }
+}