Follow common pattern for implementing IHttpRequestLifetimeFeature

src/Microsoft.AspNet.Server.Kestrel/Http/Frame.FeatureCollection.cs

@@ -231,6 +231,18 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
             }
         }
 
+        CancellationToken IHttpRequestLifetimeFeature.RequestAborted
+        {
+            get
+            {
+                return RequestAborted;
+            }
+            set
+            {
+                RequestAborted = value;
+            }
+        }
+
         bool IHttpResponseFeature.HasStarted
         {
             get { return HasResponseStarted; }
@@ -263,8 +275,6 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
 
         bool IHttpConnectionFeature.IsLocal { get; set; }
 
-        CancellationToken IHttpRequestLifetimeFeature.RequestAborted { get; set; }
-
         object IFeatureCollection.this[Type key]
         {
             get { return FastFeatureGet(key); }

src/Microsoft.AspNet.Server.Kestrel/Http/Frame.cs

@@ -89,6 +89,8 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
 
         public Stream DuplexStream { get; set; }
 
+        public CancellationToken RequestAborted { get; set; }
+
         public bool HasResponseStarted
         {
             get { return _responseStarted; }
@@ -241,7 +243,7 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
                         DuplexStream = new FrameDuplexStream(RequestBody, ResponseBody);
 
                         _requestAbortCts = CancellationTokenSource.CreateLinkedTokenSource(_disconnectCts.Token);
-                        ((IHttpRequestLifetimeFeature)this).RequestAborted = _requestAbortCts.Token;
+                        RequestAborted = _requestAbortCts.Token;
 
                         var httpContext = HttpContextFactory.Create(this);
                         try