Reject deprecated language features.

dart/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;
 
 class MessageKind {
   final String template;
   const MessageKind(this.template);
 
@@ skipping 225 matching lines @@
   static const BAD_ARITY_OVERRIDE = const MessageKind(
       "Error: cannot override method '#{1}' in '#{2}'; "
       "the parameters do not match.");
 
   static const BAD_ARITY_OVERRIDE_CONT = const MessageKind(
       "Info: this is the method whose parameters do not match.");
 
   static const MISSING_FORMALS = const MessageKind(
       "Error: Formal parameters are missing.");
 
-  // TODO(ahe): Change the message below when it becomes an error.
   static const EXTRA_FORMALS = const MessageKind(
-      "Warning: Formal parameters will not be allowed here in M1.");
+      "Error: Formal parameters are not allowed here.");
+
+  // TODO(ahe): This message is hard to localize.  This is acceptable,
+  // as it will be removed when we ship Dart version 1.0.
+  static const DEPRECATED_FEATURE_WARNING = const MessageKind(
+      "Warning: deprecated language feature, #{1}, "
+      "will be removed in a future Dart milestone.");
+
+  // TODO(ahe): This message is hard to localize.  This is acceptable,
+  // as it will be removed when we ship Dart version 1.0.
+  static const DEPRECATED_FEATURE_ERROR = const MessageKind(
+      "Error: #{1} are not legal "
+      "due to option --reject-deprecated-language-features.");
 
   static const CONSTRUCTOR_WITH_RETURN_TYPE = const MessageKind(
       "Error: cannot have return type for constructor.");
 
   static const ILLEGAL_FINAL_METHOD_MODIFIER = const MessageKind(
       "Error: cannot have final modifier on method.");
 
   static const ILLEGAL_CONSTRUCTOR_MODIFIERS = const MessageKind(
       "Error: illegal constructor modifiers: #{1}.");
 
@@ skipping 149 matching lines @@
 
 class CompileTimeConstantError extends Diagnostic {
   CompileTimeConstantError(MessageKind kind, List arguments)
     : super(kind, arguments);
 }
 
 class CompilationError extends Diagnostic {
   CompilationError(MessageKind kind, List arguments)
     : super(kind, arguments);
 }