code: function getDataFromCustomEvent(nativeEvent) {
    var detail = nativeEvent.detail;
    if ((typeof detail === 'undefined' ? 'undefined' : _typeof(detail)) === 'object' && 'data' in detail) {
      return detail.data;
    }
    return null;
  }
docs: Google Input Tools provides composition data via a CustomEvent,
  with the `data` property populated in the `detail` object. If this
  is available on the event object, use it. If not, this is a plain
  composition event and we have nothing special to extract.
  
  @param {object} nativeEvent
  @return {?string}