Edit MR diffs note does not hide original text

Description

Noticed on .com

When editing a note on an MR diff, the original text isn't hidden.

Investigation

It looks like rules with .notes > li are no longer being picked up (relevant scss). Example:

/* line 181, app/assets/stylesheets/pages/notes.scss */
.notes > li.is-editing .note-header,
.notes > li.is-editing .note-text,
.notes > li.is-editing .edited-text {
  display: none;
}

This is because !71508 (diffs) introduced an intermediary child between ul.notes and the li, actually resulting in invalid HTML: