Annotate native methods.

pkg/front_end/lib/src/fasta/loader.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.loader;
 
 import 'dart:async' show
     Future;
 
 import 'dart:collection' show
@@ skipping 132 matching lines @@
     List<InputError> errors = <InputError>[];
     for (LibraryBuilder library in builders.values) {
       if (library.loader == this) {
         errors.addAll(library.compileTimeErrors);
       }
     }
     return errors;
   }
 
   Builder getCompileTimeError() => target.getCompileTimeError(this);
+
+  Builder getNativeAnnotation() => target.getNativeAnnotation(this);
 }
 
 String format(double d, int fractionDigits, int width) {
   return d.toStringAsFixed(fractionDigits).padLeft(width);
 }