anchor.diff:  
     void resolve() {
       for (var unit in _libraryElement.units) {
  +      _unitElement = unit;
         for (var classElement in unit.types) {
           _classElement = classElement;
           for (var constructorElement in classElement.constructors) {
  
positive.code:       return;
      }
  
      for (var initializer in initializers) {
        _astResolver.resolve(
          initializer,
  
negative.code: 
  import 'package:analyzer/dart/element/element.dart';
  import 'package:analyzer/src/dart/ast/ast.dart';
  import 'package:analyzer/src/dart/element/builder.dart';
  import 'package:analyzer/src/dart/element/element.dart';
  import 'package:analyzer/src/dart/resolver/scope.dart';
  import 'package:analyzer/src/generated/resolver.dart';
  import 'package:analyzer/src/summary2/ast_resolver.dart';
  import 'package:analyzer/src/summary2/link.dart';
  import 'package:analyzer/src/summary2/linking_node_scope.dart';
  