Migrate language block 46 - canonical_const ... char_escape.

tests/language_2/cascade_2_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";
 
 // Test cascades, issues 7494 (vm), 7689 (dart2js).
 
 main() {
   var a = new Element(null);
@@ skipping 35 matching lines @@
 
   List<Element> get path1 {
     return (parent == null) ? <Element>[this] : parent.path1
       ..add(this);
   }
 
   List<Element> get path2 {
     return (parent == null) ? <Element>[this] : (parent.path2..add(this));
   }
 }