Don't assume that we always have a HowToFix and remove failing test.

tests/compiler/dart2js/message_kind_helper.dart

 // Copyright (c) 2013, 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 dart2js.test.message_kind_helper;
 
 import 'package:expect/expect.dart';
 import 'dart:async';
 
 import 'package:compiler/src/commandline_options.dart';
@@ skipping 39 matching lines @@
 
 /// Most messages can be tested without causing a fatal error. Add an exception
 /// here if a fatal error is unavoidable and leads to pending classes.
 /// Try to avoid adding exceptions here; a fatal error causes the compiler to
 /// stop before analyzing all input, and it isn't safe to reuse it.
 final Set<MessageKind> kindsWithPendingClasses = new Set<MessageKind>.from([
     // If you add something here, please file a *new* bug report.
 ]);
 
 Future<Compiler> check(MessageTemplate template, Compiler cachedCompiler) {
-  Expect.isNotNull(template.howToFix);
   Expect.isFalse(template.examples.isEmpty);
 
   return Future.forEach(template.examples, (example) {
     if (example is String) {
       example = {'main.dart': example};
     } else {
       Expect.isTrue(example is Map,
                     "Example must be either a String or a Map.");
       Expect.isTrue(example.containsKey('main.dart'),
                     "Example map must contain a 'main.dart' entry.");
@@ skipping 83 matching lines @@
                     kindsWithPendingClasses.contains(template));
 
       if (!pendingStuff) {
         // If there is pending stuff, or the compiler was cancelled, we
         // shouldn't reuse the compiler.
         cachedCompiler = compiler;
       }
     });
   }).then((_) => cachedCompiler);
 }