title: Mat-Select select currently selected option
body: <p>I need to react on option selection. My problem is that this component is not emitting event (<code>selectionChange</code> output is not emitting new events) when I have selected option A, and I open select pane and select option A again. The event is not fired because selection is not changed but I need in my use case to fire an selection change event in this case. Does somebody know how to do this? Is there any way to override <code>selectionModel</code> in this <code>mat-select</code> component? I have a list of links and after selecting any of them I need to react even when user select the same link again. I'm using <code>@angular/core@5.2.5</code> and <code>@angular/material@5.2.1</code>.</p>
  
  <p>Here is the template with this component that I want to use:</p>
  
  <pre><code>&lt;mat-form-field&gt;
      &lt;mat-select placeholder="Search history"
          [disabled]="(links | async).length === 0"
          [value]="(links | async).length &gt; 0 ? (links | async)[0] : null"
          (selectionChange)="onSearchHistorySelect($event.value)"&gt;
          &lt;mat-option *ngFor="let l of links | async" [value]="l"&gt;{{l.title}}&lt;/mat-option&gt;
      &lt;/mat-select&gt;
  &lt;/mat-form-field&gt;
  </code></pre>