createProps = (domNode, existingProps = {}) => {
  return getObserved(domNode.constructor).reduce((props, attr) => ({
    [attr]: (
      domNode.hasAttribute(attr) ? domNode.getAttribute(attr) : domNode[attr]
    ) || props[attr] || domNode.constructor.defaultProps[attr],
    ...props,
  }), existingProps);
}
Creates the `component.props` object.

@param {any} domNode
@param {Props} existingProps