Allow translated messages that have no matching original message

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 183 matching lines @@
       message = null;
       print("Error $e");
       print("Processing <$node>");
       reportErrorLocation(node);
     }
     return message;
   }
 
   void reportErrorLocation(ASTNode node) {
     if (origin != null) print("    from $origin");
-    LineInfo info = root.lineInfo;
+    var info = root.lineInfo;
     if (info != null) {
-      LineInfo_Location line = info.getLocation(node.offset);
+      var line = info.getLocation(node.offset);
       print("    line: ${line.lineNumber}, column: ${line.columnNumber}");
     }
   }
 }
 
 /**
  * Given a node that looks like an invocation of Intl.message, extract out
  * the message and the parameters and store them in [target].
  */
 class MessageVisitor extends GeneralizingASTVisitor {
@@ skipping 79 matching lines @@
    */
   final String message;
 
   /**
    * Creates a new exception with an optional error [message].
    */
   const IntlMessageExtractionException([this.message = ""]);
 
   String toString() => "IntlMessageExtractionException: $message";
 }