Migrate language block 46 - canonical_const ... char_escape.

tests/language_2/cast2_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.
 // Dart test program for constructors and initializers.
 
 import "package:expect/expect.dart";
 
 // Test 'expression as Type' casts.
 
 class C {
   final int foo = 42;
 
   int val = 0;
   void inc() {
     ++val;
   }
 }
 
 class D extends C {
   final int bar = 37;
 }
 
 main() {
   C oc = new C();
   D od = new D();
 
-  (oc as dynamic).bar; // //# 01: runtime error
+  Expect.throwsNoSuchMethodError(() => (oc as dynamic).bar);
 
   // Casts should always evaluate the left-hand side, if only for its effects.
   oc.inc() as dynamic;
   Expect.equals(1, oc.val);
   oc.inc() as Object;
   Expect.equals(2, oc.val);
 }