Portable Class Library Reflection

I am currently trying to convert a Xamarin.iOS app library to a PCL (Profile 78). I have this code that will not compile:

 public static void RegisterAllCommandHandlers(IEnumerable<Assembly> assemblies) {
            // Get all types that are concrete classes which implement ICommandHandler
            var commandHandlerOpenGenericType = typeof(ICommandHandler<>);
            var types = new List<Type>();
            foreach (var assembly in assemblies) {
                types.AddRange(assembly.GetTypes()
                      .Where(x => x.IsClass && !x.IsAbstract && x.GetInterfaces().Any(i => i.IsGenericType && i.GetGenericTypeDefinition() == commandHandlerOpenGenericType)));
            }
    }

Here is an image of the compiler errors:

How can I do the same thing with the new reflection API?