This is the followup we need to do after #6406 to remove dead code.

}
    return null;
  },
  /**
   * Creates markup for a custom property.
   *
   * @param {string} name
   * @param {*} value
   * @return {string} Markup string, or empty string if the property was invalid.
   */
  createMarkupForCustomAttribute: function(name, value) {
    if (!isAttributeNameSafe(name) || value == null) {
      return '';
    }
    return name + '=' + quoteAttributeValueForBrowser(value);
  },
  /**
   * Sets the value for a property on a node.
   *
   * @param {DOMElement} node
   * @param {string} name
   * @param {*} value
   */
  setValueForProperty: function(node, name, value) {
    var propertyInfo = DOMProperty.properties.hasOwnProperty(name) ?
        DOMProperty.properties[name] : null;
    if (propertyInfo) {
      var mutationMethod = propertyInfo.mutationMethod;
      if (mutationMethod) {
        mutationMethod(node, value);