title: wrong icon in material angular stepper
body: <p>I'm trying to put a edit icon when a state is "address", but the icon is the must of the first state (home).</p>
  
  <p>I try:</p>
  
  <p><strong>First step:</strong></p>
  
  <pre><code>&lt;ng-template matStepperIcon="edit"&gt;
              &lt;mat-icon&gt;home&lt;/mat-icon&gt;
            &lt;/ng-template&gt;
  
            &lt;mat-step label="Antes de começar..." state="home"&gt;
  ..........
  </code></pre>
  
  <p><strong>Second step:</strong></p>
  
  <pre><code>&lt;ng-template matStepperIcon="address"&gt;
      &lt;mat-icon&gt;edit&lt;/mat-icon&gt;
  &lt;/ng-template&gt;
  
  &lt;mat-step label="Dados do seu pet..." [stepControl]="secondFormGroup" state="address"&gt;    
          &lt;div&gt;
              &lt;button mat-button matStepperPrevious&gt;Back&lt;/button&gt;
              &lt;button mat-button matStepperNext&gt;Next&lt;/button&gt;
          &lt;/div&gt;
  </code></pre>
  
  <p>This is showing:</p>
  
  <p><a href="https://i.stack.imgur.com/gsOHl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gsOHl.png" alt="enter image description here"></a></p>
  
  <p>The second step must be a edit icon but have the icon of the first step why?</p>