Tweak message.

pkg/front_end/lib/src/fasta/kernel/kernel_class_builder.dart

 // Copyright (c) 2016, 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 fasta.kernel_class_builder;
 
 import 'package:kernel/ast.dart'
     show
         Class,
         Constructor,
@@ skipping 212 matching lines @@
           "The method '$name::${declaredMember.name.name}' has fewer "
           "positional arguments than those of overridden method "
           "'${interfaceMember.enclosingClass.name}::"
           "${interfaceMember.name.name}'.");
     }
     if (interfaceFunction.requiredParameterCount <
         declaredFunction.requiredParameterCount) {
       addWarning(
           declaredMember.fileOffset,
           "The method '$name::${declaredMember.name.name}' has more "
-          "positional arguments than those of overridden method "
+          "required arguments than those of overridden method "
           "'${interfaceMember.enclosingClass.name}::"
           "${interfaceMember.name.name}'.");
     }
     if (declaredFunction.namedParameters.isEmpty &&
         interfaceFunction.namedParameters.isEmpty) {
       return;
     }
     if (declaredFunction.namedParameters.length <
         interfaceFunction.namedParameters.length) {
       addWarning(
@@ skipping 30 matching lines @@
   }
 
   void addWarning(int charOffset, String message) {
     library.addWarning(charOffset, message, fileUri: fileUri);
   }
 
   void addNit(int charOffset, String message) {
     library.addNit(charOffset, message, fileUri: fileUri);
   }
 }