Describe the bug
Using getElementsByClassName again on an element that has been found will cause the function to not exist.

To Reproduce
https://stackblitz.com/edit/js-xmldom-template-qg6pz5?file=index.js

Expected behavior
should be able to do the getElementsByClassName operation from the found child elements

Runtime & Version:
xmldom version: 0.8.10
runtime version:
other related software and version:

Additional context
none