merge_pr_46953

[reading-flow] Display: contents elements can be focusable

CSSWG has resolved that reading-flow does not affect whether an element
is focusable. Given this, we should remove the check in Element that
forbids display: contents with reading-flow to be focusable.

We update the FocusNavigation logic such that the display: contents
elements are visited last, after all reading flow items found within the
layout box.

Change-Id: Iadd9636166628361b001df7b63b2ee98072a89d5
Bug: 346979043
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5656691
Reviewed-by: Mason Freed masonf@chromium.org
Commit-Queue: Di Zhang dizhangg@chromium.org
Cr-Commit-Position: refs/heads/main@{#1321829}