Add 'meaning' to Intl.messages

pkg/intl/lib/extract_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.
 
 /**
  * This is for use in extracting messages from a Dart program
  * using the Intl.message() mechanism and writing them to a file for
  * translation. This provides only the stub of a mechanism, because it
  * doesn't define how the file should be written. It provides an
  * [IntlMessage] class that holds the extracted data and [parseString]
@@ skipping 262 matching lines @@
   MainMessage messageFromDirectPluralOrGenderCall(MethodInvocation node) {
     var pluralOrGender;
 
     void extractFromPluralOrGender(MainMessage message, _) {
       var visitor = new PluralAndGenderVisitor(message.messagePieces, message);
       node.accept(visitor);
       pluralOrGender = message.messagePieces.last;
     }
 
     void setAttribute(MainMessage msg, String fieldName, String fieldValue) {
-      if (["name", "desc", "examples", "args"].contains(fieldName)) {
+      if (msg.attributeNames.contains(fieldName)) {
         msg[fieldName] = fieldValue;
       }
     }
     return _messageFromNode(node, extractFromPluralOrGender, setAttribute);
   }
 }
 
 /**
  * Given an interpolation, find all of its chunks, validate that they are only
  * simple variable substitutions or else Intl.plural/gender calls,
@@ skipping 112 matching lines @@
     SimpleIdentifier target = node.target;
     return target.token.toString() == "Intl";
   }
 
   /**
    * Returns a String describing why the node is invalid, or null if no
    * reason is found, so it's presumed valid.
    */
   String checkValidity(MethodInvocation node) {
     // TODO(alanknight): Add reasonable validity checks.
+    return null;
   }
 
   /**
    * Create a MainMessage from [node] using the name and
    * parameters of the last function/method declaration we encountered            e
    * and the parameters to the Intl.message call.
    */
   Message messageFromMethodInvocation(MethodInvocation node) {
     var message;
     switch(node.methodName.name) {
@@ skipping 40 matching lines @@
    */
   final String message;
 
   /**
    * Creates a new exception with an optional error [message].
    */
   const IntlMessageExtractionException([this.message = ""]);
 
   String toString() => "IntlMessageExtractionException: $message";
 }