Update Tree.php
Update Tree.php

$deleteSucceeded is unused before.
```
toastr.success('{$deleteSucceeded}');
```
never615/laravel-admin,never615/laravel-admin,z-song/laravel-admin,z-song/laravel-admin,qq447665722/laravel-admin,qq447665722/laravel-admin,qq447665722/laravel-admin