`container` variable in internal ancestor origin objects list creation steps is unused

[AtkinsSJ]

What is the issue with the HTML Standard?

https://html.spec.whatwg.org/multipage/dom.html#internal-ancestor-origin-objects-list-creation-steps step 6 creates a container variable:

6. Let container be document's node navigable's container.

However, this isn't used in any subsequent steps.

cc: @zcorpan: This was added in #11560