title: ng-touched not resetting on .markAsUntouched for a Custom Control
body: <p>I have a simple custom control in an an Angular 2 form that when it you edit  the field then reset it via the <strong>.markAsUntouched</strong>, it doesn't remove the <strong>ng-touched</strong> class. </p>
  
  <p>The sample form looks like this:</p>
  
  <pre><code>&lt;form #editForm="ngForm"&gt;
      &lt;input [(ngModel)]="title" name="title2" type="text"/&gt;
      &lt;app-textbox label="Template Driven Model" [showLabel]="true" 
       [(ngModel)]="title" name="title"&gt; &lt;/app-textbox&gt;
       &lt;button (click)="resetTempalteDriven()"&gt;Reset Template Driven&lt;/button&gt;
   &lt;/form&gt;
  </code></pre>
  
  <p>In this example the standalone input control resets correctly. The app-textbox component's html looks like this:</p>
  
  <pre><code>&lt;div&gt;
  &lt;div class="fg-line"&gt;
      &lt;label *ngIf="label &amp;&amp; showLabel" [ngClass]="{ 'font-bold': required }"&gt;{{label}}&lt;/label&gt;
      &lt;input type="text"   style="cursor: text" 
          [(ngModel)]="value" [required]="required" [disabled]="disabled" [placeholder]="placeholder" [id]="identifier" /&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p></p>
  
  <p>And the reset for the form looks like this:</p>
  
  <pre><code>  resetTempalteDriven(){ 
  
        this.editForm.form.markAsPristine();
        this.editForm.form.markAsUntouched();
  
        this.editForm.controls["title"].markAsUntouched();
     }
  </code></pre>
  
  <p>I have put the entire app here <a href="https://github.com/jmarbutt/ng2-angular-issue" rel="nofollow noreferrer">https://github.com/jmarbutt/ng2-angular-issue</a></p>
  
  <p>The form looks like this after touching both input fields then hitting reset.
  <a href="https://i.stack.imgur.com/vfLtn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vfLtn.png" alt="enter image description here"></a></p>
  
  <p>They both should be white at this point.</p>
  
  <p>So my question is why does the ng-touched not remove correctly on the <strong>markAsUntouched</strong>?</p>