anchor.diff:      _match(partial.identifier, element);
       (partial as SimpleFormalParameterImpl).declaredElement = element;
       _metadata(partial.metadata, element);
  +  }
  +
  +  void _topLevelVariableDeclaration(
  +    TopLevelVariableDeclaration full,
  +    TopLevelVariableDeclaration partial,
  +  ) {
  +    _node(full.variables, partial.variables);
  +
  +    var first = partial.variables.variables[0];
  +    _metadata(partial.metadata, first.declaredElement);
     }
   
     void _typeName(TypeName full, TypeName partial) {
  
positive.code:       _enumDeclaration(full, partial);
        return partial;
      } else if (full is FieldDeclaration && partial is FieldDeclaration) {
        _node(full.fields, partial.fields);
        return partial;
      } else if (full is FieldFormalParameter &&
          partial is FieldFormalParameter) {
  
negative.code:       var elementBuilder = LocalElementBuilder(ElementHolder(), null);
        partial.initializer?.accept(elementBuilder);
      }
    }
  
    void _variableDeclarationList(
  