Clean build warnings

src/Kestrel/ServerRequest.cs

@@ -221,7 +221,7 @@ namespace Kestrel
             }
         }
 
-        async Task<Stream> IHttpUpgradeFeature.UpgradeAsync()
+        Task<Stream> IHttpUpgradeFeature.UpgradeAsync()
         {
             _frame.StatusCode = 101;
             _frame.ReasonPhrase = "Switching Protocols";
@@ -235,7 +235,7 @@ namespace Kestrel
                 }
             }
             _frame.ProduceStart();
-            return _frame.DuplexStream;
+            return Task.FromResult(_frame.DuplexStream);
         }
     }
 }

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

@@ -1,7 +1,9 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+#if DNX451
 using System;
+#endif
 using System.IO;
 using System.Threading;
 using System.Threading.Tasks;

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

@@ -1,11 +1,11 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-using Microsoft.AspNet.Server.Kestrel.Networking;
 using System;
 using System.Collections.Generic;
-using System.Threading;
 using System.Diagnostics;
+using System.Threading;
+using Microsoft.AspNet.Server.Kestrel.Networking;
 
 namespace Microsoft.AspNet.Server.Kestrel.Http
 {

test/Microsoft.AspNet.Server.KestrelTests/EngineTests.cs

@@ -76,7 +76,7 @@ namespace Microsoft.AspNet.Server.KestrelTests
         }
 
         [Fact]
-        public async Task EngineCanStartAndStop()
+        public void EngineCanStartAndStop()
         {
             var engine = new KestrelEngine(LibraryManager, new ShutdownNotImplemented());
             engine.Start(1);
@@ -84,7 +84,7 @@ namespace Microsoft.AspNet.Server.KestrelTests
         }
 
         [Fact]
-        public async Task ListenerCanCreateAndDispose()
+        public void ListenerCanCreateAndDispose()
         {
             var engine = new KestrelEngine(LibraryManager, new ShutdownNotImplemented());
             engine.Start(1);
@@ -95,7 +95,7 @@ namespace Microsoft.AspNet.Server.KestrelTests
 
 
         [Fact]
-        public async Task ConnectionCanReadAndWrite()
+        public void ConnectionCanReadAndWrite()
         {
             var engine = new KestrelEngine(LibraryManager, new ShutdownNotImplemented());
             engine.Start(1);

test/Microsoft.AspNet.Server.KestrelTests/MessageBodyTests.cs

@@ -16,7 +16,7 @@ namespace Microsoft.AspNet.Server.KestrelTests
     public class MessageBodyTests
     {
         [Fact]
-        public async Task Http10ConnectionClose()
+        public void Http10ConnectionClose()
         {
             var input = new TestInput();
             var body = MessageBody.For("HTTP/1.0", new Dictionary<string, string[]>(), input.FrameContext);

test/Microsoft.AspNet.Server.KestrelTests/NetworkingTests.cs

@@ -45,7 +45,7 @@ namespace Microsoft.AspNet.Server.KestrelTests
         }
 
         [Fact]
-        public async Task LoopCanBeInitAndClose()
+        public void LoopCanBeInitAndClose()
         {
             var loop = new UvLoopHandle();
             loop.Init(_uv);
@@ -54,7 +54,7 @@ namespace Microsoft.AspNet.Server.KestrelTests
         }
 
         [Fact]
-        public async Task AsyncCanBeSent()
+        public void AsyncCanBeSent()
         {
             var loop = new UvLoopHandle();
             loop.Init(_uv);
@@ -72,7 +72,7 @@ namespace Microsoft.AspNet.Server.KestrelTests
         }
 
         [Fact]
-        public async Task SocketCanBeInitAndClose()
+        public void SocketCanBeInitAndClose()
         {
             var loop = new UvLoopHandle();
             loop.Init(_uv);