anchor.diff:  )
   class TemplateUrlComponent {
   }
  +
  +@Component(
  +    selector: 'log-bind',
  +    map: const {
  +      'optional-one': '=>optional',
  +      'optional-two': '<=>optional',
  +      'optional-once': '=>!optional',
  +    }
  +)
  +class LoggedBinding {
  +  Logger logger;
  +  LoggedBinding(this.logger);
  +  set optional(input) => logger(input);
  +}
  
positive.code:           ..bind(ConditionalContentComponent)
            ..bind(ExprAttrComponent)
            ..bind(LogElementComponent)
            ..bind(SayHelloFormatter)
            ..bind(OuterComponent)
            ..bind(InnerComponent)
  
negative.code:           ..bind(Parent, toValue: null)
            ..bind(Child)
            ..bind(ChildTemplateComponent)
            ..bind(TranscludeChildrenWithAttributeDirective)
            ..bind(LoggedBinding)
            ..bind(InjectorDependentComponent);
      });
  
      beforeEach((TestBed tb) => _ = tb);
  