anchor.diff:    /// The element for the library containing the compilation unit being visited.
     final LibraryElement _definingLibrary;
   
  +  /// The URI of [_definingLibrary].
  +  final Uri _definingLibraryUri;
  +
     /// The object keeping track of which elements have had their types promoted.
  -  TypePromotionManager _promoteManager;
  +  final TypePromotionManager _promoteManager;
  +
  +  /// The [Name] object of the invocation being resolved by [resolve].
  +  Name _currentName;
   
     MethodInvocationResolver(this._resolver)
         : _typeType = _resolver.typeProvider.typeType,
           _inheritance = _resolver.inheritance,
           _definingLibrary = _resolver.definingLibrary,
  +        _definingLibraryUri = _resolver.definingLibrary.source.uri,
           _promoteManager = _resolver.promoteManager;
   
     /// The scope used to resolve identifiers.
  
positive.code:   ExecutableElement _lookUpClassMember(ClassElement element, String name) {
      // TODO(scheglov) Use class hierarchy.
      return element.lookUpMethod(name, _definingLibrary);
    }
  
    /// Return a signature of a member of a superinterface of [type].
    /// It might be abstract.
    /// TODO(scheglov) Replace this with class hierarchy.
    FunctionType _lookUpInheritedMember(InterfaceType type, Name name) {
      for (var mixin in type.mixins.reversed) {
        var result = _inheritance.getMember(mixin, name);
        if (result != null) return result;
      }
      {
        var result = _inheritance.getMember(type.superclass, name);
        if (result != null) return result;
      }
      for (var interface in type.interfaces) {
        var result = _inheritance.getMember(interface, name);
        if (result != null) return result;
      }
      return null;
    }
  
    void _reportInvocationOfNonFunction(MethodInvocation node) {
  
negative.code:     var receiverType = _resolver.enclosingClass.type;
      var targetType = _inheritance.getMember(
        receiverType,
        _currentName,
        forSuper: true,
      );
  
  