Introduce constraints of deferred constants.

sdk/lib/_internal/compiler/implementation/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 = "";
 
 /**
  * The messages in this file should meet the following guide lines:
@@ skipping 535 matching lines @@
   static const MessageKind SWITCH_CASE_VALUE_OVERRIDES_EQUALS =
       const MessageKind(
           "'case' expression type '#{type}' overrides 'operator =='.");
 
   static const MessageKind INVALID_ARGUMENT_AFTER_NAMED = const MessageKind(
       "Unnamed argument after named argument.");
 
   static const MessageKind NOT_A_COMPILE_TIME_CONSTANT = const MessageKind(
       "Not a compile-time constant.");
 
+  static const MessageKind DEFERRED_COMPILE_TIME_CONSTANT = const MessageKind(
+      "Deferred classes cannot be used to create compile-time constants.");
+
   static const MessageKind CYCLIC_COMPILE_TIME_CONSTANTS = const MessageKind(
       "Cycle in the compile-time constant computation.");
 
   static const MessageKind CONSTRUCTOR_IS_NOT_CONST = const MessageKind(
       "Constructor is not a 'const' constructor.");
 
   static const MessageKind CONST_MAP_KEY_OVERRIDES_EQUALS =
       const MessageKind(
           "Const-map key type '#{type}' overrides 'operator =='.");
 
@@ skipping 1349 matching lines @@
     return computeMessage();
   }
 
   bool operator==(other) {
     if (other is !Message) return false;
     return (kind == other.kind) && (toString() == other.toString());
   }
 
   int get hashCode => throw new UnsupportedError('Message.hashCode');
 }