Make "error" the default severity for checked mode compile time errors.

pkg/analyzer/lib/src/generated/error.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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.error;
 
 import 'dart:collection';
@@ skipping 2375 matching lines @@
 
   /**
    * Compile-time errors are errors that preclude execution. A compile time error must be reported
    * by a Dart compiler before the erroneous code is executed.
    */
   static const ErrorType COMPILE_TIME_ERROR = const ErrorType('COMPILE_TIME_ERROR', 2, ErrorSeverity.ERROR);
 
   /**
    * Checked mode compile-time errors are errors that preclude execution in checked mode.
    */
-  static const ErrorType CHECKED_MODE_COMPILE_TIME_ERROR = const ErrorType('CHECKED_MODE_COMPILE_TIME_ERROR', 3, ErrorSeverity.INFO);
+  static const ErrorType CHECKED_MODE_COMPILE_TIME_ERROR = const ErrorType('CHECKED_MODE_COMPILE_TIME_ERROR', 3, ErrorSeverity.ERROR);
 
   /**
    * Static warnings are those warnings reported by the static checker. They have no effect on
    * execution. Static warnings must be provided by Dart compilers used during development.
    */
   static const ErrorType STATIC_WARNING = const ErrorType('STATIC_WARNING', 4, ErrorSeverity.WARNING);
 
   /**
    * Many, but not all, static warnings relate to types, in which case they are known as static type
    * warnings.
@@ skipping 1776 matching lines @@
 
   @override
   String get message => "{0}";
 
   @override
   ErrorType get type => ErrorType.TODO;
 
   @override
   String get uniqueName => "${runtimeType.toString()}.${name}";
 }