The video poster is not shown when preload="auto", triggering a imagefailure against the reference file. wpt.fyi link: https://wpt.fyi/results/html/semantics/embedded-content/the-video-element/video-poster-shown-preload-auto.html?label=master&product=chrome%5Bexperimental%5D&product=firefox%5Bexperimental%5D&product=safari%5Bexperimental%5D&product=webkitgtk&aligned
Fixed by https://bugs.webkit.org/show_bug.cgi?id=218391 Gardening and closing...
Created attachment 415417 [details] Patch for landing
Committed r270432: <https://trac.webkit.org/changeset/270432> All reviewed patches have been landed. Closing bug and clearing flags on attachment 415417 [details].
<rdar://problem/71980296>