title: change event not getting fired in angular 6
body: <p>Hi i am calling method onchange event but for calender input it is not getting applied.Below is the code.[(change)="makeDirty()"].It is working for description textbox but not working for date picker textbox.</p>
  
  <pre><code>    &lt;div class="form-group mb-10"&gt;
        &lt;label class="formLabel"&gt;Description&lt;/label&gt;
        &lt;input type="text" (change)="makeDirty()" class="form-control bg-grey" [(ngModel)]='description' [ngModelOptions]="{standalone:true}"&gt;
      &lt;/div&gt;
  
      &lt;div class="form-group mb-10"&gt;
          &lt;label class="formLabel"&gt;Period&lt;/label&gt;
          &lt;input type="text" (change)="makeDirty()" placeholder="select start date and end date" class="form-control bg-grey" #dp="bsDaterangepicker"
            bsDaterangepicker [(ngModel)]="bsRangeValue" [placement]="'top'" [outsideClick]="false" [bsConfig]="{  showWeekNumbers:false,containerClass: 'theme-dark-blue',rangeInputFormat: 'DD/MM/YYYY' }"
            formControlName="Period"&gt;
          &lt;span class="glyphicon glyphicon-calendar glyicon" (click)="dp.toggle()" [attr.aria-expanded]="dp.isOpen"
            value="Toggle" style="top:36px"&gt;&lt;/span&gt;
          &lt;div class="alert  alert-danger" *ngIf="formGroup.get('Period').dirty &amp;&amp; formGroup.get('Period').errors &amp;&amp; formGroup.get('Period').errors.ageRange "&gt;
            Date range selected is invalid
          &lt;/div&gt;
        &lt;/div&gt;
  </code></pre>