Migrate language block 46 - canonical_const ... char_escape.

tests/language_2/cascade_in_initializer_list_test.dart

 // Copyright (c) 2013, 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";
 
 class A {
   foo() {}
   bar() {}
 }
 
 class B {
   var x;
   final y;
 
   B(a)
       : x = a
           ..foo()
           ..bar(),
         y = a
           ..foo()
           ..bar() {}
 }
 
 main() {
   var a = new A(), b = new B(a);
   Expect.equals(a, b.x);
   Expect.equals(a, b.y);
 }