remove duplicated function

public/trivabble.js

@@ -57,11 +57,6 @@
             Object.prototype.hasOwnProperty.call(localStorage, key);
     }
 
-    function isSetting(key) {
-        return Object.prototype.hasOwnProperty.call(Conf, key) ||
-            Object.prototype.hasOwnProperty.call(localStorage, key);
-    }
-
     function getSetting(key) {
         let type = undefined;
         let value = undefined;