Remove the argument from main in a test

tests/kernel/unsorted/generic_function_test.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Tests of generic functions.
 
 import 'package:expect/expect.dart';
 
 typedef R Foo<R>();
 
 bar<R>(int body()) {
   var function = () {
     if (body is Foo<R>) {
       return body();
     }
     return 42;
   };
   return function();
 }
 
-main(args) {
+main() {
   Expect.isTrue(bar(() => 43) == 43);
 }