`npm run build --prod` strip decorators meta

[kingfolk]

The following code reproduce SomeComponent is not injectable. Because design:paramtypes metadata is stripped by Angular during production build.

import {Dilight, Injectable, Module, Injector} from 'dilight';

@Injectable()
class ServiceA {}

@Injectable()
class ServiceB {
  constructor(private a: ServiceA) {}
}

@Module({
  providers: [ServiceB],
})
class SomeComponent {
  constructor(public childInjector: Injector) {}
}

const parentInjector = Dilight.new();
const comp = parentInjector.get(SomeComponent);

// will log false
console.log(comp.childInjector.get(ServiceB) === parentInjector.get(ServiceB));

// will log true
console.log(comp.childInjector.get(ServiceA) === parentInjector.get(ServiceA));