Simpler Connection test

Author: benaadams

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

@@ -642,23 +642,11 @@ private Task CreateResponseHeader(
             var end = begin;
             if (_keepAlive && _responseHeaders.HasConnection)
             {
-                var count = _responseHeaders.HeaderConnection.Count;
-                if (count == 1)
+                var connection = _responseHeaders.HeaderConnection.ToString();
+
+                if (connection.IndexOf("close", StringComparison.OrdinalIgnoreCase) != -1)
                 {
-                    if (_responseHeaders.HeaderConnection[0].IndexOf("close", StringComparison.OrdinalIgnoreCase) != -1)
-                    {
-                        _keepAlive = false;
-                    }
-                }
-                else if (count > 1)
-                { 
-                    foreach (var connectionValue in _responseHeaders.HeaderConnection)
-                    {
-                        if (connectionValue.IndexOf("close", StringComparison.OrdinalIgnoreCase) != -1)
-                        {
-                            _keepAlive = false;
-                        }
-                    }
+                    _keepAlive = false;
                 }
             }