Extract 'computeMissingOverrides' in ErrorVerifier.

pkg/analyzer/lib/error/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.
 
 library analyzer.error.error;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/listener.dart';
@@ skipping 854 matching lines @@
       const ErrorProperty<List<FieldElement>>('NOT_INITIALIZED_FIELDS', 0);
 
   /**
    * A property whose value is the name of the library that is used by all
    * of the "part of" directives, so should be used in the "library" directive.
    * Is `null` if there is no a single name used by all of the parts.
    */
   static const ErrorProperty<String> PARTS_LIBRARY_NAME =
       const ErrorProperty<String>('PARTS_LIBRARY_NAME', 1);
 
-  /**
-   * A property whose value is a list of [ExecutableElement] that should
-   * be but are not implemented by a concrete class.
-   */
-  static const ErrorProperty<List<ExecutableElement>> UNIMPLEMENTED_METHODS =
-      const ErrorProperty<List<ExecutableElement>>('UNIMPLEMENTED_METHODS', 2);
-
   static const List<ErrorProperty> values = const [
     NOT_INITIALIZED_FIELDS,
     PARTS_LIBRARY_NAME,
-    UNIMPLEMENTED_METHODS
   ];
 
   /**
    * The name of this property.
    */
   final String name;
 
   /**
    * The ordinal value of the property.
    */
   final int ordinal;
 
   const ErrorProperty(this.name, this.ordinal);
 
   @override
   int get hashCode => ordinal;
 
   @override
   int compareTo(ErrorProperty other) => ordinal - other.ordinal;
 
   @override
   String toString() => name;
 }