bug#56815: 29.0.50; Isearch lazy-highlight highlights too much when truncate-lines is in effect

[Lars Ingebrigtsen]

This reminds me of something I wondered about when futzing about with
inhibiting lazy-highlights w.r.t. text covered by a `display' property
(which was fixed a different way):

Would it be possibly to make the isearch lazy-highlight just skip the
portions of the buffer that aren't visible?