MDCTextField: textarea element no longer has outline

[RobJacobs]

What MDC Web Version are you using?

Latest from master branch

What browser(s) is this bug affecting?

Chrome, Edge

What are the steps to reproduce the bug?

1. Run the demo server
2. Go to localhost:8080/textfield.html
3. Click in the Textarea example
4. Observe the component's behavior

What is the expected behavior?

textarea element should have an outline

What is the actual behavior?

textarea element does not have an outline

Any other information you believe would be useful?

Textfield with a textarea markup example shows:

<div class="mdc-text-field mdc-text-field--textarea">
  <textarea id="textarea" class="mdc-text-field__input" rows="8" cols="40"></textarea>
  <label for="textarea" class="mdc-floating-label">Textarea Label</label>
</div>

Using the following markup restores outline:

<div class="mdc-text-field mdc-text-field--textarea">
  <textarea id="textarea" class="mdc-text-field__input" rows="8" cols="40"></textarea>
  <div class="mdc-notched-outline">
    <div class="mdc-notched-outline__leading"></div>
    <div class="mdc-notched-outline__notch">
      <label for="textarea" class="mdc-floating-label">Textarea Label</label>
    </div>
    <div class="mdc-notched-outline__trailing"></div>
  </div>
</div>