Call for Consensus: Discontinuing Page Visibility

Hey folks,

As discussed at PageVisibility#74
<https://github.com/w3c/page-visibility/issues/74> and at TPAC
<https://w3c.github.io/web-performance/meetings/2021/2021-10-TPAC/index.html#h.n3yvkdpnm2i>,
the algorithms for Page Visibility
<https://www.w3.org/TR/page-visibility-2/> were folded into HTML, and it no
longer makes sense to maintain it as a separate specification.

This is a Call for Consensus to publish the Page Visibility as a
Discontinued Draft and then redirect links to it to the relevant sections
in the HTML spec.

Please reply with any objections you may have until May 17th.

Thanks!
Yoav