Fix an issue with restoring certain lint issues from summary files.

pkg/analyzer/lib/src/dart/error/lint_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.dart.error.lint_codes;
 
 import 'package:analyzer/error/error.dart';
 
 /**
  * Defines style and best practice recommendations.
  *
  * Unlike [HintCode]s, which are akin to traditional static warnings from a
  * compiler, lint recommendations focus on matters of style and practices that
  * might aggregated to define a project's style guide.
  */
 class LintCode extends ErrorCode {
   const LintCode(String name, String message, [String correction])
       : super(name, message, correction);
 
   @override
   ErrorSeverity get errorSeverity => ErrorSeverity.INFO;
 
   @override
   ErrorType get type => ErrorType.LINT;
+
+  /**
+   * Overridden so that [LintCode] and its subclasses share the same uniqueName
+   * pattern (we know how to identify a lint even if we don't know the specific
+   * subclass the lint's code is defined in.
+   */
+  String get uniqueName => "LintCode.$name";
 }