message: Remove bits of Field that supported uncontrolled
  Field is no longer used as an uncontrolled component, so we can remove some
  supporting code that we no longer need.
diff: @@ -53,22 +53,9 @@ export default class Field extends React.PureComponent {
  };
  }
  - /* TODO: Remove me */
  - get value() {
  - if (!this.refs.fieldInput) return null;
  - return this.refs.fieldInput.value;
  - }
  -
  - set value(newValue) {
  - if (!this.refs.fieldInput) {
  - throw new Error("No field input reference");
  - }
  - this.refs.fieldInput.value = newValue;
  - }
  -
  onChange = (ev) => {
  if (this.props.onValidate) {
  - const result = this.props.onValidate(this.value);
  + const result = this.props.onValidate(ev.target.value);
  this.setState({
  valid: result.valid,
  feedback: result.feedback,
  @@ -92,12 +79,6 @@ export default class Field extends React.PureComponent {
  inputProps.onChange = this.onChange;
  - /* TODO: Remove me */
  - // make sure we use the current `value` for the field and not the original one
  - if (inputProps.value === undefined) {
  - inputProps.value = this.value || "";
  - }
  -
  const fieldInput = React.createElement(inputElement, inputProps, children);
  let prefixContainer = null;
  