Migrate block 44.

tests/language/built_in_identifier_illegal_test.dart

-// Copyright (c) 2012, 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.
-// Check that we cannot use a pseudo keyword at the class level code.
-
-// Pseudo keywords are not allowed to be used as class names.
-class abstract { } //   //# 01: compile-time error
-class as { } //         //# 19: compile-time error
-class dynamic { } //    //# 04: compile-time error
-class export { } //     //# 17: compile-time error
-class external { } //   //# 20: compile-time error
-class factory { } //    //# 05: compile-time error
-class get { } //        //# 06: compile-time error
-class implements { } // //# 07: compile-time error
-class import { } //     //# 08: compile-time error
-class library { } //    //# 10: compile-time error
-class operator { } //   //# 12: compile-time error
-class part { } //       //# 18: compile-time error
-class set { } //        //# 13: compile-time error
-class static { } //     //# 15: compile-time error
-class typedef { } //    //# 16: compile-time error
-
-main() {}