Create values for literal Strings.

frog/tests/leg_only/src/SimpleStringConstantTest.dart

Index: frog/tests/leg_only/src/SimpleStringConstantTest.dart
diff --git a/frog/tests/leg_only/src/SimpleStringConstantTest.dart b/frog/tests/leg_only/src/SimpleStringConstantTest.dart
new file mode 100644
index 0000000000000000000000000000000000000000..ceee2deabc77738fb2bd0a8497f5c4c44cb8461a
--- /dev/null
+++ b/frog/tests/leg_only/src/SimpleStringConstantTest.dart
@@ -0,0 +1,9 @@
+// Copyright (c) 2011, 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.
+
+final String m = "\u{21}";
+
+main() {
+  Expect.equals('!', m);
+}