Como faço para converter .net 4.5 Async / Await example volta para 4.0

Como seria o código equivallent do asp.net mvc 4.0?

using System.Net;
using System.Net.Http;
using System.Web.Mvc;
using System.Threading.Tasks;
using Newtonsoft.Json;
namespace Web.Controllers
{
    public class HomeController : Controller
    {
        private HttpClient httpClient = new HttpClient();
        private static dynamic shots;

        public async Task<ActionResult> Index()
        {
            if (shots == null)
            {
                try
                {
                    var responseMessage = 
                       await httpClient.GetAsync
                            ("http://api.dribbble.com/shots/everyone?per_page=30");
                    responseMessage.EnsureSuccessStatusCode();

                    var value = await responseMessage.Content.ReadAsStringAsync();
                    shots = await JsonConvert.DeserializeObjectAsync<dynamic>(value);
                }
                catch (WebException)
                {
                }
            }
            return View(shots);
        }
    }
}

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