Form Validation Cookbook: reactive example component doesnt declare the active property.

[SafeEval]

In the (Form Validation)[https://angular.io/docs/ts/latest/cookbook/form-validation.html] cookbook, the reactive form component example code ("reactive/hero-form-reactive.component.ts (#3)") doesn't declare the active class property, but does reference it on lines 28 and 29.

active = true; is declared in the accompanying Plunker code on line 30.