Fix private_test to reflect new, better warning.

tests/compiler/dart2js/private_test.dart

 // Copyright (c) 2012, 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.
 
 import "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
 import 'mock_compiler.dart';
 
 import 'package:compiler/src/io/source_file.dart';
 import 'package:compiler/src/dart2jslib.dart';
@@ skipping 113 matching lines @@
   analyze('var value = publicClass.private.publicMethod;');
   // Call public method on private class.
   analyze('publicClass.private.publicMethod();');
 
   // Call unnamed (public) constructor on public class.
   analyze('publicClass = new PublicClass();');
   // Call public constructor on public class.
   analyze('publicClass = new PublicClass.publicConstructor();');
   // Call private constructor on public class.
   analyze('publicClass = new PublicClass._privateConstructor();',
-      MessageKind.CANNOT_FIND_CONSTRUCTOR);
+      MessageKind.PRIVATE_ACCESS);
   // Read from private field on public class.
   analyze('var value = publicClass._privateField;',
       MessageKind.PRIVATE_ACCESS);
   // Write to private field on public class.
   analyze('publicClass._privateField = 0;',
       MessageKind.PRIVATE_ACCESS);
   // Call private getter on public class.
   analyze('var value = publicClass._privateGetter;',
       MessageKind.PRIVATE_ACCESS);
   // Call private setter on public class.
@@ skipping 13 matching lines @@
   // Call public getter on public class.
   analyze('var value = publicClass.publicGetter;');
   // Call public setter on public class.
   analyze('publicClass.publicSetter = 0;');
   // Access public method on public class.
   analyze('var value = publicClass.publicMethod;');
   // Call public method on public class.
   analyze('publicClass.publicMethod();');
 }