[spartanatreyu]

To add a little context to the rabbit hole, I'm fairly certain the reason why subgrid has taken so long on chromium based engines is because it was deemed not worth implementing on their old layout stack and would be much easier to work with in their new layout stack (LayoutNG).

The new layout stack took a little time to get out the door, solving weird issues with certain use cases that just wouldn't be able to be solved with the old layout stack (at least not without becoming a nightmare).

Now that it's out, there's a bunch of commits made from both google and microsoft emails working on reimplementing grid (GridNG) in the new layout system in such a way that grid stage 2 (subgrid) and grid stage 3 (masonry) extensions will be easier to maintain.