Split MessageKind into a MessageKind key and a MessageTemplate.

pkg/compiler/lib/src/elements/modelx.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.
 
 library elements.modelx;
 
 import 'common.dart';
 import 'elements.dart';
 import '../constants/expressions.dart';
 import '../constants/constructors.dart';
 import '../helpers/helpers.dart';
 import '../tree/tree.dart';
 import '../util/util.dart';
 import '../resolution/resolution.dart';
 import '../resolution/class_members.dart' show ClassMemberMixin;
 
 import '../dart2jslib.dart' show
     Backend,
     Compiler,
     Constant,
     DartType,
     DiagnosticListener,
     DualKind,
     FunctionType,
     InterfaceType,
     MessageKind,
+    MessageTemplate,
     Script,
     Selector,
     SourceSpan,
     TypeVariableType,
     TypedefType,
     invariant,
     isPrivateName;
 
 import '../dart_types.dart';
 
@@ skipping 264 matching lines @@
   bool get hasFunctionSignature => false;
 
   get effectiveTarget => this;
 
   computeEffectiveTargetType(InterfaceType newType) => unsupported();
 
   get definingConstructor => null;
 
   FunctionElement asFunctionElement() => this;
 
-  String get message => '${messageKind.message(messageArguments)}';
+  String get message {
+    return MessageTemplate.TEMPLATES[messageKind]
+        .message(messageArguments).toString();
+  }
 
   String toString() => '<$name: $message>';
 
   accept(ElementVisitor visitor, arg) {
     return visitor.visitErroneousElement(this, arg);
   }
 
   @override
   bool get isFromEnvironmentConstructor => false;
 }
@@ skipping 2576 matching lines @@
   AstElement get definingElement;
 
   bool get hasResolvedAst => definingElement.hasTreeElements;
 
   ResolvedAst get resolvedAst {
     return new ResolvedAst(declaration,
         definingElement.node, definingElement.treeElements);
   }
 
 }