anchor.diff:  
     @override
     DecoratedType visitConditionalExpression(ConditionalExpression node) {
  -    _handleAssignment(node.condition, destinationType: _notNullType);
  +    _handleAssignment(node.condition, destinationType: _nonNullableBoolType);
   
       DecoratedType thenType;
       DecoratedType elseType;
  
positive.code: 
    @override
    DecoratedType visitIfElement(IfElement node) {
      _handleAssignment(node.condition, destinationType: _notNullType);
      NullabilityNode trueGuard;
      NullabilityNode falseGuard;
      if (identical(_conditionInfo?.condition, node.condition)) {
  
negative.code:   @override
    DecoratedType visitDoStatement(DoStatement node) {
      node.body.accept(this);
      _handleAssignment(node.condition, destinationType: _nonNullableBoolType);
      return null;
    }
  
  