Fixed #3579 - Missing using in startup template on _layout.cshtm (ASP.NET MVC 5.x +Multi Page Web Application)

Author: alirizaadiyahsi

src/AbpCompanyName.AbpProjectName.WebMpa/Views/Shared/_Layout.cshtml

@@ -6,6 +6,7 @@
 @using AbpCompanyName.AbpProjectName.Configuration
 @using Abp.Dependency
 @using Abp.Web.Mvc.Alerts
+@using Abp.Web.Mvc.Extensions
 @{
     Layout = null;
     SetAntiForgeryCookie();