Add an examples getter for all Message objects in Intl

pkg/intl/lib/src/intl_message.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.
 
 /**
  * This provides classes to represent the internal structure of the
  * arguments to `Intl.message`. It is used when parsing sources to extract
  * messages or to generate code for message substitution. Normal programs
  * using Intl would not import this library.
  *
@@ skipping 39 matching lines @@
    * All [Message]s except a [MainMessage] are contained inside some parent,
    * terminating at an Intl.message call which supplies the arguments we
    * use for variable substitutions.
    */
   Message parent;
 
   Message(this.parent);
 
   /**
    * We find the arguments from the top-level [MainMessage] and use those to
-   * do variable substitutions.
+   * do variable substitutions. [MainMessage] overrides this to return
+   * the actual arguments.
    */
   get arguments => parent == null ? const [] : parent.arguments;
 
+  /**
+   * We find the examples from the top-level [MainMessage] and use those
+   * when writing out variables. [MainMessage] overrides this to return
+   * the actual examples.
+   */
+  get examples => parent == null ? const [] : parent.examples;
+
   String checkValidity(MethodInvocation node, List arguments,
                        String outerName, FormalParameterList outerArgs) {
     var hasArgs = arguments.any(
         (each) => each is NamedExpression && each.name.label.name == 'args');
     var hasParameters = !outerArgs.parameters.isEmpty;
     if (!hasArgs && hasParameters) {
       return "The 'args' argument for Intl.message must be specified";
     }
 
     var messageName = arguments.firstWhere(
@@ skipping 587 matching lines @@
     out.write('(');
     out.write(mainArgument);
     var args = codeAttributeNames;
     out.write(", {");
     args.fold(out, (buffer, arg) => buffer..write(
         "'$arg': '${this[arg].toCode()}', "));
     out.write("})}");
     return out.toString();
   }
 }