React to string[] -> StringValue changes.

src/Microsoft.AspNet.Diagnostics.Elm/ElmPageMiddleware.cs

@@ -118,7 +118,7 @@ namespace Microsoft.AspNet.Diagnostics.Elm
                 }
                 if (context.Request.Query.ContainsKey("name"))
                 {
-                    var namePrefix = context.Request.Query.GetValues("name")[0];
+                    var namePrefix = context.Request.Query["name"];
                     options.NamePrefix = namePrefix;
                 }
             }

src/Microsoft.AspNet.Diagnostics/ErrorHandlerMiddleware.cs

@@ -7,6 +7,7 @@ using Microsoft.AspNet.Builder;
 using Microsoft.AspNet.Http;
 using Microsoft.AspNet.Http.Features;
 using Microsoft.Framework.Logging;
+using Microsoft.Net.Http.Headers;
 
 namespace Microsoft.AspNet.Diagnostics
 {
@@ -87,10 +88,10 @@ namespace Microsoft.AspNet.Diagnostics
         private Task ClearCacheHeaders(object state)
         {
             var response = (HttpResponse)state;
-            response.Headers.Set("Cache-Control", "no-cache");
-            response.Headers.Set("Pragma", "no-cache");
-            response.Headers.Set("Expires", "-1");
-            response.Headers.Remove("ETag");
+            response.Headers[HeaderNames.CacheControl] = "no-cache";
+            response.Headers[HeaderNames.Pragma] = "no-cache";
+            response.Headers[HeaderNames.Expires] = "-1";
+            response.Headers.Remove(HeaderNames.ETag);
             return Task.FromResult(0);
         }
     }

src/Microsoft.AspNet.Diagnostics/Views/DiagnosticsPage.cs

@@ -27,7 +27,7 @@ using System.Globalization
 #line 3 "DiagnosticsPage.cshtml"
   
     Response.ContentType = "text/html";
-    string error = Request.Query.Get("error");
+    string error = Request.Query["error"];
     if (!string.IsNullOrWhiteSpace(error))
     {
         throw new InvalidOperationException(string.Format(CultureInfo.InvariantCulture, "User requested error '{0}'", error));

src/Microsoft.AspNet.Diagnostics/Views/ErrorPageModel.cs

@@ -4,6 +4,7 @@
 
 using System.Collections.Generic;
 using Microsoft.AspNet.Http;
+using Microsoft.Framework.Primitives;
 
 namespace Microsoft.AspNet.Diagnostics.Views
 {
@@ -38,14 +39,6 @@ namespace Microsoft.AspNet.Diagnostics.Views
         /// Request headers.
         /// </summary>
         [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly", Justification = "Model class contains collection")]
-        public IDictionary<string, string[]> Headers { get; set; }
-
-        /* TODO:
-        /// <summary>
-        /// The request environment
-        /// </summary>
-        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly", Justification = "Model class contains collection")]
-        public HttpContext Environment { get; set; }
-        */
+        public IDictionary<string, StringValues> Headers { get; set; }
     }
 }