Add Claims dependency.

src/Microsoft.AspNet.HttpFeature/Security/IAuthenticationResult.cs

@@ -1,7 +1,5 @@
 using System.Collections.Generic;
-#if NET45
 using System.Security.Claims;
-#endif
 using Microsoft.AspNet.HttpFeature.Security;
 
 // ReSharper disable once CheckNamespace
@@ -9,11 +7,7 @@ namespace Microsoft.AspNet.Interfaces.Security
 {
     public interface IAuthenticationResult
     {
-#if NET45
         ClaimsIdentity Identity { get; }
-#else
-        
-#endif
         IDictionary<string, object> Properties { get; }
         IAuthenticationDescription Description { get; }
     }

src/Microsoft.AspNet.HttpFeature/Security/IAuthenticationSignIn.cs

@@ -1,15 +1,11 @@
 using System.Collections.Generic;
-#if NET45
 using System.Security.Claims;
-#endif
 
 namespace Microsoft.AspNet.HttpFeature.Security
 {
     public interface IAuthenticationSignIn
     {
-#if NET45
         ClaimsPrincipal User { get; }
-#endif
         IDictionary<string, string> Properties { get; }
     }
 }

src/Microsoft.AspNet.HttpFeature/project.json

@@ -7,6 +7,7 @@
         "System.IO": "4.0.0.0",
         "System.Runtime": "4.0.20.0",
         "System.Runtime.InteropServices": "4.0.10.0",
+        "System.Security.Claims": "0.1-alpha-*",
         "System.Security.Principal": "4.0.0.0",
         "System.Threading.Tasks": "4.0.0.0"
       }