Timeout property at new HttpClient implementation was ignored (#700)

* Timeout property at new HttpClient implementation was not working well for .NET Framework

* Reuse conversion to milliseconds.

(cherry picked from commit 81a94df)

dotnet/src/dotnetframework/GxClasses/Domain/GxHttpClient.cs

@@ -646,9 +646,14 @@ HttpResponseMessage ExecuteRequest(string method, string requestUrl, CookieConta
 			if (proxy != null)
 				handler.Proxy = proxy;
 			HttpResponseMessage response;
+			TimeSpan milliseconds = TimeSpan.FromMilliseconds(_timeout);
+#if !NETCORE
+			handler.ReceiveDataTimeout = milliseconds;
+			handler.ReceiveHeadersTimeout = milliseconds;
+#endif
 			using (client = new HttpClient(handler))
 			{
-				client.Timeout = TimeSpan.FromMilliseconds(_timeout);
+				client.Timeout = milliseconds;
 				client.BaseAddress = request.RequestUri;
 
 				using (MemoryStream reqStream = new MemoryStream())