Remove toplevel inference restriction hints, and restore as much

pkg/analyzer/lib/src/error/codes.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 analyzer.src.error.codes;
 
 import 'package:analyzer/error/error.dart';
 
 export 'package:analyzer/src/analysis_options/error/option_codes.dart';
 export 'package:analyzer/src/dart/error/hint_codes.dart';
@@ skipping 4984 matching lines @@
       ErrorType.COMPILE_TIME_ERROR,
       'NOT_INSTANTIATED_BOUND',
       "Type parameter bound types must be instantiated.",
       "Try adding type arguments.");
 
   /*
    * TODO(brianwilkerson) Make the TOP_LEVEL_ error codes be errors rather than
    * hints and then clean up the function _errorSeverity in
    * test/src/task/strong/strong_test_helper.dart.
    */
+  /* TODO(leafp) Delete most of these.  
+   */
   static const StrongModeCode TOP_LEVEL_CYCLE = const StrongModeCode(
       ErrorType.HINT,
       'TOP_LEVEL_CYCLE',
       "The type of '{0}' can't be inferred because it depends on itself through the cycle: {1}.",
       "Try adding an explicit type to one or more of the variables in the cycle in order to break the cycle.");
 
   static const StrongModeCode TOP_LEVEL_FUNCTION_LITERAL_BLOCK =
       const StrongModeCode(
           ErrorType.HINT,
           'TOP_LEVEL_FUNCTION_LITERAL_BLOCK',
@@ skipping 48 matching lines @@
    * created from the optional [correction] template.
    */
   const StrongModeCode(ErrorType type, String name, String message,
       [String correction])
       : type = type,
         super('STRONG_MODE_$name', message, correction);
 
   @override
   ErrorSeverity get errorSeverity => type.severity;
 }