Migrating another batch of tests to dart 2.

tests/language_2/compile_time_constant11_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 conditional expression can be a compile-time constant.
 
 import "package:expect/expect.dart";
 
 const C1 = true;
 const C2 = false;
 
 const nephew = C1 ? C2 ? "Tick" : "Trick" : "Track";
 
 main() {
   const a = true ? 5 : 10;
   const b = C2 ? "Track" : C1 ? "Trick" : "Tick";
 
   Expect.equals(5, a);
   Expect.equals("Trick", nephew);
   Expect.equals(nephew, b);
   Expect.identical(nephew, b);
   var s = const Symbol(nephew);
   var msg = "Donald is $nephew's uncle.";
   Expect.equals("Donald is Trick's uncle.", msg);
 }