Chrome keeps 50 entries a tab, and when the list is full a new entry drops the
oldest one the page left without a user gesture, which can be the page's own
entry under a sub-view or an overlay. A programmatic back() then left the
document; once it landed on an older entry whose restored Plex player started
playing on its own. Every programmatic back() now asks the Navigation API first
and, with no entry of this document below, settles in place: the sub-view turns
to its root, an overlay's entry drops its mark, the channel page and the YouTube
search clear.