fix always refresh webview after change tab

AppBuilder/AppBuilder/FirstTabViewController.swift

@@ -192,7 +192,6 @@ class FirstTabViewController: UIViewController, UIScrollViewDelegate, UIGestureR
     }
     
     override func viewWillAppear(_ animated: Bool) {
-        FirstTabViewController.forceRefresh = true
         if FirstTabViewController.canLoadURL {
             processURL()
         }