title: defaultValue is not filled in textarea when used with react-final-form
body: <p>I unable set the defaultValue to the text area, I am using <a href="https://github.com/final-form/react-final-form/" rel="nofollow noreferrer">react-final-form</a> and wrapped the TextareaField inside the Field element of react-final-form</p>
  
  <p>Here is my code:</p>
  
  <pre><code>class App extends React.Component {
    submitForm(values) {
     .....
    }
  
   renderForm({ handleSubmit }) {
    return (
     &lt;form
      onSubmit={handleSubmit}
     &gt;
      &lt;Field
        name="description"
      &gt;
        {({ input, meta }) =&gt; (
          &lt;TextareaField
            label='Description'
            error={meta.error}
            isInvalid={meta.submitFailed &amp;&amp; !meta.valid}
            inputAttrs={{
              placeholder: 'Desc..',
            }}
            defaultValue='my text'
            onChange={(e) =&gt; { input.onChange(e.target.value); }}
            value={input.value}
            required
          /&gt;
        )}
      &lt;/Field&gt;
      &lt;Button text="Submit" type={Button.Opts.Types.SUBMIT} /&gt;
    &lt;/form&gt;
   );
  }
  render() {
    return (
      &lt;Form
        onSubmit={this.submitForm}
        render={this.renderForm}
        validate={(values) =&gt; {
          const errors = {};
          if (!values.description) {
            errors.description = 'Required';
          }
          return errors;
        }}
      /&gt;
     );
   }
  }
  </code></pre>
  
  <p>Terribly stuck, where am I missing??</p>