wrong painting order for abs.pos. boxes inside flex items that has been reordered with 'order'

• Component: CSS
• Status: NEW ---

[Karl Dubost]

Test case at https://codepen.io/webcompat/pen/qBKqpwZ
Initially reported on https://bugs.chromium.org/p/chromium/issues/detail?id=606208

> Flex and grid containers lay out their contents in order-modified document order, starting from the lowest numbered ordinal group and going up. Items with the same ordinal group are laid out in the order they appear in the source document. This also affects the painting order [CSS2], exactly as if the flex/grid items were reordered in the source document. Absolutely-positioned children of a flex/grid container are treated as having order: 0 for the purpose of determining their painting order relative to flex/grid items.
— https://drafts.csswg.org/css-display-3/#order-property

Being discussed as a candidate on Interop 2023
- https://github.com/web-platform-tests/interop/issues/187#issuecomment-1294877815

[Radar WebKit Bug Importer]

<rdar://problem/102355371>

[Tim Nguyen (:ntim)]

rdar://74279579