Singleton providers leak non-singleton dependencies

[guyca]

In the following example, useCase is retained throwout the lifespan of all PushedScreenGraphinstances, while presenter is meant to be retained only for the lifespan of the PushedScreen component this graph instance is bound to.

@Graph()
class PushedScreenGraph {
  @Provides()
  presenter(): PushedScreenPresenter {
    return new PushedScreenPresenter();
  }

  @Provides() @Singleton()
  someUseCase(presenter: PushedScreenPresenter): SomeUseCase {
    return new SomeUseCase(presenter);
  }
}