Revert "third_party/protobuf: Update to HEAD (83d681ee2c)"

third_party/protobuf/csharp/src/Google.Protobuf/Compatibility/PropertyInfoExtensions.cs

 #region Copyright notice and license
 // Protocol Buffers - Google's data interchange format
 // Copyright 2015 Google Inc.  All rights reserved.
 // https://developers.google.com/protocol-buffers/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
@@ skipping 29 matching lines @@
     /// targeting the newer releases, .NET Core etc.
     /// </summary>
     internal static class PropertyInfoExtensions
     {
         /// <summary>
         /// Returns the public getter of a property, or null if there is no such getter
         /// (either because it's read-only, or the getter isn't public).
         /// </summary>
         internal static MethodInfo GetGetMethod(this PropertyInfo target)
         {
-#if DOTNET35
-            var method = target.GetGetMethod();
-#else
             var method = target.GetMethod;
-#endif
             return method != null && method.IsPublic ? method : null;
         }
 
         /// <summary>
         /// Returns the public setter of a property, or null if there is no such setter
         /// (either because it's write-only, or the setter isn't public).
         /// </summary>
         internal static MethodInfo GetSetMethod(this PropertyInfo target)
         {
-#if DOTNET35
-            var method = target.GetSetMethod();
-#else
             var method = target.SetMethod;
-#endif
             return method != null && method.IsPublic ? method : null;
         }
     }
 }