title: ngSwitch not working in ngFor
body: <p>I am trying to use ngSwitch within ngFor and it doesn't seem to be working.
  Below is the Test code I Have written (Note: i am using Devextreme UI, hence the dx-* tags)</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;dx-tab-panel
      #tabPanel
      [dataSource]="companies"
      [selectedIndex]="0"
      [loop]="false"
      [animationEnabled]="true"
      [swipeEnabled]="true"
  &gt;
  
   &lt;dxi-item [title]="item.Title" *ngFor="let item of currView"&gt;  
    &lt;ng-container [ngSwitch]="item.Title"&gt; 
     &lt;ng-container *ngSwitchCase="TARs"&gt; 
      &lt;p&gt;TEST&lt;/p&gt;
     &lt;/ng-container&gt;
     &lt;iframe *ngSwitchDefault [src]="item.Src | safeUrl"&gt;&lt;/iframe&gt;
    &lt;/ng-container&gt;  
   &lt;/dxi-item&gt;
  &lt;/dx-tab-panel&gt;</code></pre>
  </div>
  </div>
  </p>