ToH Ch7:HTTP - missing instructions to edit method goBack() in hero-detail.component.ts

[jchatkinson]

At the end of Ch6, the goBack method in app/hero-detail.component.ts looks like:

goBack() {
      window.history.back();
}

Instructions should be added to modify this method to:

goBack(savedHero: Hero = null) {
    this.close.emit(savedHero);
    if (this.navigated) { window.history.back(); }
  }

so that it can be used as shown in the save method:
this.goBack(hero);

[wardbell]

Closed by #1478