Adds facilities for extracting Intl.message calls and generating code from translations

pkg/intl/test/message_extraction/part_of_sample_with_messages.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.part of sample;
+
+part of sample;
+
+class YouveGotMessages {
+
+  // A static message, rather than a standalone function.
+  static staticMessage() => Intl.message("This comes from a static method",
+      name: 'staticMessage');
+
+  // An instance method, rather than a standalone function.
+  method() => Intl.message("This comes from a method", name: 'method');
+
+  // A non-lambda, i.e. not using => syntax, and with an additional statement
+  // before the Intl.message call.
+  nonLambda() {
+    // TODO(alanknight): I'm really not sure that this shouldn't be disallowed.
+    var x = 'something';
+    return Intl.message("This method is not a lambda", name: 'nonLambda');
+  }
+
+// TODO(alanknight): Support plurals and named arguments.
+//  plurals(num) => Intl.message("""
+//One of the tricky things is ${Intl.plural(num,
+//      {
+//        '0' : 'the plural form',
+//        '1' : 'the plural form',
+//        'other' : 'plural forms'})}""",
+//    name: "plurals");
+//
+//namedArgs({thing}) => Intl.message("The thing is, $thing", name: "namedArgs");
+}