frontend tests: retry should retry with the same padName, which was not true in case there was no padName supplied (#4206)

tests/frontend/helper.js

@@ -112,13 +112,13 @@ var helper = {};
       helper.clearSessionCookies();
     }
 
-    // needed for retry
-    let origPadName = padName;
-
     if(!padName)
       padName = "FRONTEND_TEST_" + helper.randomString(20);
     $iframe = $("<iframe src='/p/" + padName + (encodedParams || '') + "'></iframe>");
 
+    // needed for retry
+    let origPadName = padName;
+
     //clean up inner iframe references
     helper.padChrome$ = helper.padOuter$ = helper.padInner$ = null;