module Nokogiri::HTML5::Node

def add_child_node_and_reparent_attrs(node)

actually create the xml namespace if it doesn't exist already.
annoying with attribute names like xml:lang since libxml2 will
and tries to create an attribute in a namespace. This is especially
Nokogiri::XML::Node#[]= treats names with colons as a prefixed QName
HTML elements can have attributes that contain colons. 
def add_child_node_and_reparent_attrs(node)
  return super unless document.is_a?(HTML5::Document)
  # I'm not sure what this method is supposed to do. Reparenting
  # namespaces is handled by libxml2, including child namespaces which
  # this method wouldn't handle.
  # https://github.com/sparklemotion/nokogiri/issues/1790
  add_child_node(node)
  # node.attribute_nodes.find_all { |a| a.namespace }.each do |attr|
  #  attr.remove
  #  ns = attr.namespace
  #  a["#{ns.prefix}:#{attr.name}"] = attr.value
  # end
end