Migrate language block 46 - canonical_const ... char_escape.

tests/language_strong/cha_deopt3_test.dart

-// Copyright (c) 2014, 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.
-// VMOptions=--optimization-counter-threshold=100
-
-// Test lazy deoptimization at type checks with interface implementation.
-
-import "package:expect/expect.dart";
-import "cha_deopt3_lib.dart";
-import "cha_deopt3_deferred_lib.dart" deferred as d;
-
-var loaded = false;
-
-main() {
-  for (var i = 0; i < 2000; i++) bla();
-  Expect.equals(1, bla());
-  d.loadLibrary().then((_) {
-    loaded = true;
-    Expect.equals(1, bla());
-  });
-}
-
-make_array() {
-  try {
-    if (loaded) {
-      return [new A(), new B(), new C(), new D(), new E(), d.make_u()];
-    } else {
-      return [new A(), new B(), new C(), new D(), new E(), new T()];
-    }
-  } catch (e) {}
-}
-
-bla() {
-  var count = 0;
-  for (var x in make_array()) {
-    if (x is T) count++;
-  }
-  return count;
-}