Migrate language block 46 - canonical_const ... char_escape.

tests/language_strong/cha_deopt1_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 field guards with deferred loading.
-
-import "package:expect/expect.dart";
-import "cha_deopt1_lib.dart";
-import "cha_deopt1_deferred_lib.dart" deferred as d;
-
-var loaded = false;
-
-main() {
-  for (var i = 0; i < 2000; i++) bla();
-  Expect.equals(42, bla());
-  d.loadLibrary().then((_) {
-    loaded = true;
-    Expect.equals("good horse", bla());
-  });
-}
-
-make_t() {
-  try {
-    if (loaded) {
-      return d.make_u();
-    } else {
-      return new T();
-    }
-  } catch (e) {}
-}
-
-bla() {
-  var x = new X();
-  x.test(make_t());
-  return x.fld.m();
-}
-
-class X {
-  T fld = new T();
-
-  test(T t) {
-    if (t != null) {
-      T tmp = t;
-      fld = tmp;
-    }
-  }
-}