Fixes code_transformers after the latest analyzer changes

pkg/code_transformers/test/resolver_test.dart

 // Copyright (c) 2014, 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 code_transformers.test.resolver_test;
 
 import 'dart:async';
 import 'dart:io' show File, Platform;
 
 import 'package:barback/barback.dart';
@@ skipping 143 matching lines @@
       return validateResolver(
           inputs: {
             'a|web/main.dart': '''
               import 'package:b/b.dart';
 
               main() {
               } ''',
           },
           messages: [
             'error: Unable to find asset for "package:b/b.dart"',
-            'error: Unable to find asset for "package:b/b.dart"',
           ],
           validator: (resolver) {
             var lib = resolver.entryLibrary;
             expect(lib.importedLibraries.length, 1);
           });
     });
 
     test('should fail on absolute URIs', () {
       return validateResolver(
           inputs: {
@@ skipping 177 matching lines @@
     this.resolvers = resolvers;
   }
 
   Future<bool> isPrimary(Asset input) =>
       new Future.value(input.id == primary);
 
   applyResolver(Transform transform, Resolver resolver) {
     return validator(resolver);
   }
 }