`<template>.content` May not be working in I.E. 11 after `DomContentLoaded`

[Ahmid-Ra]

Code is in an I.I.F.E. which does not get called on subsequent insertions into the DOM.
Could be problematic for dynamic custom elements.

See https://github.com/devpunks/snuggsi/blob/master/html-template-element/index.polyfill.es