Migrating block 50, first commit, after tool has run

tests/language_2/compile_time_constant_b_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.
 
 import "package:expect/expect.dart";
 
 const m1 = const {'__proto__': 400 + 99};
 const m2 = const {'a': 499, 'b': 42};
 const m3 = const {'__proto__': 499};
 
@@ skipping 57 matching lines @@
   Expect.throws(() => m2['a'] = 499, isUnsupportedError);
   Expect.throws(() => m2['b'] = 42, isUnsupportedError);
   Expect.throws(() => m2['__proto__'] = 499, isUnsupportedError);
   Expect.throws(() => m2.putIfAbsent('a', () => 499), isUnsupportedError);
   Expect.throws(
       () => m2.putIfAbsent('__proto__', () => 499), isUnsupportedError);
   Expect.throws(() => m2['a'] = 499, isUnsupportedError);
 
   Expect.isTrue(identical(m1, m3));
 }