The shelf laid out each loaded page only in its next animation frame. A
browser that holds frames (a background tab, headless WebKit under CPU
load, seen holding them for more than 5 s) left the grid empty while the
caption already showed the count. A loaded batch is now laid out at once
when the grid is in the document; measurements still flush per frame.
The regression test holds every animation frame and fails before the fix
on all four projects.
Vito
1ce2577733