Update url-demo.js from https://github.com/upa-url/upa

From commit: upa-url/upa@a3b9e2c

Author: rmisev

demo/url-demo.js

@@ -44,7 +44,9 @@ function showResult(url) {
 }
 
 function onInpChange() {
-  showResult(getUrl());
+  const url = getUrl();
+  showResult(url);
+  url.delete();
 }
 
 function onSetterChange() {