TODO

$.fn.contents() can return the reference of HTMLTemplateElement.prototype.content, not childNodes.

Such as how <iframe /> is supported --- https://github.com/jquery/jquery/blob/1.12-stable/src/traversing.js#L144

Reference

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/template#Attributes