Split MessageKind into a MessageKind key and a MessageTemplate.

tests/compiler/dart2js/mock_compiler.dart

 // Copyright (c) 2012, 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.
 
 library mock_compiler;
 
 import "package:expect/expect.dart";
 import 'dart:async';
 import 'dart:collection';
 
@@ skipping 148 matching lines @@
    * library.
    */
   void registerSource(Uri uri, String source) {
     sourceFiles[uri.toString()] = new MockFile(source);
   }
 
   // TODO(johnniwinther): Remove this when we don't filter certain type checker
   // warnings.
   void reportWarning(Spannable node, MessageKind messageKind,
                      [Map arguments = const {}]) {
+    MessageTemplate template = MessageTemplate.TEMPLATES[messageKind];
     reportDiagnostic(node,
-                     messageKind.message(arguments, terseDiagnostics),
+                     template.message(arguments, terseDiagnostics),
                      api.Diagnostic.WARNING);
   }
 
   void reportDiagnostic(Spannable node,
                         Message message,
                         api.Diagnostic kind) {
     var diagnostic = new WarningMessage(node, message);
     if (kind == api.Diagnostic.CRASH) {
       crashes.add(diagnostic);
     } else if (kind == api.Diagnostic.ERROR) {
@@ skipping 220 matching lines @@
   MockElement(Element enclosingElement)
       : super('', ElementKind.FUNCTION, Modifiers.EMPTY,
               enclosingElement);
 
   get node => null;
 
   parseNode(_) => null;
 
   bool get hasNode => false;
 }