Replace unowned modifier with weak for LikesListController parent pro…

…perty

WordPress/Classes/ViewRelated/Likes/LikesListController.swift

@@ -30,7 +30,7 @@ class LikesListController: NSObject {
     private let tableView: UITableView
     private var loadingIndicator = UIActivityIndicatorView()
     private weak var delegate: LikesListControllerDelegate?
-    private unowned var parent: UIViewController
+    private weak var parent: UIViewController
 
     // Used to control pagination.
     private var isFirstLoad = true