anchor.diff:    PowersetBitsDomain(this._closedWorld);
   
     CommonElements get commonElements => _closedWorld.commonElements;
  +
  +  DartTypes get dartTypes => _closedWorld.dartTypes;
   
     int get trueMask => 1 << _trueIndex;
     int get falseMask => 1 << _falseIndex;
  
positive.code: 
    int createFromStaticType(DartType type,
        {ClassRelation classRelation = ClassRelation.subtype, bool nullable}) {
      // TODO(coam): This only works for bool
      int bits = otherMask;
      if (type is InterfaceType && _isBoolSubtype(type.element)) {
        bits = boolMask;
      }
      if (nullable) {
        bits = bits | nullMask;
      }
      return bits;
    }
  
    int get asyncStarStreamType => powersetTop;
  
  
negative.code: import '../../constants/values.dart';
  import '../../elements/entities.dart';
  import '../../elements/names.dart';
  import '../../elements/types.dart';
  import '../../ir/static_type.dart';
  import '../../universe/selector.dart';
  import '../../world.dart';
  