It doesn’t have a `@flow` annotation. We should start Flow-ifying it to avoid bugs like https://github.com/facebook/react/pull/11173.

@iamdustan Wanna take it?
tagVerbatim,
  tagLowercase,
  props,
  namespace,
  makeStaticMarkup,
  isRootElement,
) {
  var ret = '<' + tagVerbatim;
  for (var propKey in props) {
    if (!props.hasOwnProperty(propKey)) {
      continue;
    }
    var propValue = props[propKey];
    if (propValue == null) {
      continue;
    }
    if (propKey === STYLE) {
      propValue = createMarkupForStyles(propValue);
    }
    var markup = null;
    if (isCustomComponent(tagLowercase, props)) {
      if (!RESERVED_PROPS.hasOwnProperty(propKey)) {
        markup = DOMMarkupOperations.createMarkupForCustomAttribute(
          propKey,
          propValue,
        );