anchor.diff:  import 'package:analyzer/dart/element/element.dart';
   import 'package:analyzer/dart/element/type.dart';
   import 'package:analyzer/src/dart/element/handle.dart';
  -import 'package:analyzer/src/dart/element/inheritance_manager2.dart';
  +import 'package:analyzer/src/dart/element/inheritance_manager3.dart';
   import 'package:analyzer/src/dart/element/member.dart';
   import 'package:analyzer/src/dart/element/type.dart';
   import 'package:analyzer/src/generated/resolver.dart';
  
positive.code:   EdgeBuilder(TypeProvider typeProvider, TypeSystem typeSystem, this._variables,
        this._graph, this._source, this.listener)
        : _decoratedClassHierarchy = DecoratedClassHierarchy(_variables, _graph),
          _inheritanceManager = InheritanceManager2(typeSystem),
          _notNullType = DecoratedType(typeProvider.objectType, _graph.never),
          _nonNullableBoolType =
              DecoratedType(typeProvider.boolType, _graph.never),
  
negative.code: /// variables that will determine its nullability.  For `visit...` methods that
  /// don't visit expressions, `null` will be returned.
  class EdgeBuilder extends GeneralizingAstVisitor<DecoratedType> {
    final InheritanceManager3 _inheritanceManager;
  
    /// The repository of constraint variables and decorated types (from a
    /// previous pass over the source code).
  