title: angular mat-menu not showing using matMenuTriggerFor
body: <p>I'm trying to create a simple menu to show when clicking on a button, but I'm not able to get <code>matMenuTriggerFor</code> to work. You can see the whole project at <a href="https://github.com/yperess/risc16" rel="nofollow noreferrer">https://github.com/yperess/risc16</a> (it's basically just a stub).</p>
  <p>The main issue is the toolbar component:</p>
  <pre><code>&lt;button mat-button [matMenuTriggerFor]=&quot;fileMenu&quot;&gt;File&lt;/button&gt;
  &lt;mat-menu #fileMenu=&quot;matMenu&quot;&gt;
    &lt;button mat-menu-item&gt;Hello&lt;/button&gt;
  &lt;/mat-menu&gt;
  </code></pre>
  <p>Here, clicking on the File button doesn't open the menu.</p>