Refactor handling of library prefixes.

pkg/compiler/lib/src/warnings.dart

 // 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.
 
 part of dart2js;
 
 const DONT_KNOW_HOW_TO_FIX = "Computer says no!";
 
 /**
  * The messages in this file should meet the following guide lines:
@@ skipping 383 matching lines @@
 
   static const MessageKind DUPLICATE_EXPORT_DECL = const MessageKind(
       "The exported '#{name}' from export #{uriString} is defined here.");
 
   static const MessageKind NOT_A_TYPE = const MessageKind(
       "'#{node}' is not a type.");
 
   static const MessageKind NOT_A_PREFIX = const MessageKind(
       "'#{node}' is not a prefix.");
 
+  static const MessageKind PREFIX_AS_EXPRESSION = const MessageKind(
+      "Library prefix '#{prefix}' is not a valid expression.");
+
   static const MessageKind CANNOT_FIND_CONSTRUCTOR = const MessageKind(
       "Cannot find constructor '#{constructorName}'.");
 
   static const MessageKind CYCLIC_CLASS_HIERARCHY = const MessageKind(
       "'#{className}' creates a cycle in the class hierarchy.");
 
   static const MessageKind CYCLIC_REDIRECTING_FACTORY = const MessageKind(
       'Redirecting factory leads to a cyclic redirection.');
 
   static const MessageKind INVALID_RECEIVER_IN_INITIALIZER = const MessageKind(
@@ skipping 2199 matching lines @@
   static String convertToString(value) {
     if (value is ErrorToken) {
       // Shouldn't happen.
       return value.assertionMessage;
     } else if (value is Token) {
       value = value.value;
     }
     return '$value';
   }
 }