#8589 / #7387 (comment) propose new properties to alter the reading order of the items to follow the layout tree order, rather than the dom order.

However, that is in conflict with #2632 / mozilla/standards-positions#772, in the sense that there doesn't seem to be a good order for display: contents elements that are focusable in a visually-order container.

We need to sort out how these two proposals interact. What is the tab order of a display: contents element inside an element with non-auto reading-order?

cc @rachelandrew @tabatkins @fantasai @dbaron