У вашего броузера проблема в совместимости с HTML5
Watch the webinar to see the latest technical demos of the Telerik UI suites, all of which are Visual Studio 2017 RC ready, newly introduced components, and the Getting Started experience improvements made across the whole portfolio of Telerik developer tools. For more information go to: http://www.telerik.com/campaigns/devcraft/february-2017-release