title: matTextareaAutosize does not work in Angular Material 6.4.2
body: <p>I am trying apply auto-sizing on textarea in angular material 6.4.2 like below -</p>
  
  <pre><code>&lt;mat-form-field&gt;
        &lt;textarea matInput [matTextareaAutosize]="true" placeholder="Task description" formControlName="description" [errorStateMatcher]="ErrorMatcher"&gt;
         &lt;/textarea&gt;
  &lt;/mat-form-field&gt;
  </code></pre>
  
  <p>But it is throwing following error: Can't bind to 'matTextareaAutosize' since it isn't a known property of 'textarea'</p>
  
  <p>What the wrong in my code?</p>