title: Angular 5 FormGroup reset doesn't reset validators
body: <p>I have a form on my page and when I call <code>FormGroup.reset()</code> it sets the forms class to <code>ng-pristine ng-untouched</code> but <code>FormControl.hasError(...)</code> still returns truthy. What am I doing wrong here?</p>
  <p><strong>Template</strong></p>
  <pre><code>&lt;form [formGroup]=&quot;myForm&quot; (ngSubmit)=&quot;submitForm(myForm)&quot;&gt;
    &lt;mat-form-field&gt;
      &lt;input matInput formControlName=&quot;email&quot; /&gt;
      &lt;mat-error *ngIf=&quot;email.hasError('required')&quot;&gt;
        Email is a required feild
      &lt;/mat-error&gt;
    &lt;/mat-form-field&gt;
    &lt;mat-form-field&gt;
      &lt;input matInput type=&quot;password&quot; formControlName=&quot;password&quot; /&gt;
      &lt;mat-error *ngIf=&quot;password.hasError('required')&quot;&gt;
        Password is a required feild
      &lt;/mat-error&gt;
    &lt;/mat-form-field&gt;
    &lt;button type=&quot;submit&quot;&gt;Login&lt;/button&gt;
  &lt;/form&gt;
  </code></pre>
  <p><strong>Component</strong></p>
  <pre><code>export class MyComponent {
    private myForm: FormGroup;
    private email: FormControl = new FormContorl('', Validators.required);
    private password: FormControl = new FormControl('', Validators.required);
  
    constructor(
      private formBuilder: FormBuilder
    ) {
      this.myForm = formBuilder.group({
        email: this.email,
        password: this.password
      });
    }
  
    private submitForm(formData: any): void {
      this.myForm.reset();
    }
  }
  </code></pre>
  <p><strong>Plunker</strong></p>
  <p><a href="https://embed.plnkr.co/Hlivn4/" rel="noreferrer">https://embed.plnkr.co/Hlivn4/</a></p>