修复限购商品跳转的bug

@@ -344,6 +344,7 @@ class CartModel
                 )
             ));
 
+            $result['skn'] = $skn;
             $result['isLimit'] = true;
         }
 

@@ -321,7 +321,7 @@ class IndexController extends AbstractAction
 
         // 限购商品时更换返回按钮地址
         if (isset($order['isLimit'])) {
-            $returnUrl = Helpers::url('/product/show_' . $skn . '.html');;
+            $returnUrl = Helpers::url('/product/show_' . $order['skn'] . '.html');;
         }
 
         $data = array(