[reading-flow] fix pseudo element reading traversal
Pseudo elements should not be included in the focus navigation because
they cannot be focused. For normal focus navigation, we use
ElementTraversal which avoids including them. For reading flow, we
should exclude them from the generated list of reading flow children.
For A11Y tree, pseudo elements should be included as AXObject.
Change-Id: I00cc9d38bf9acd61bc49adbd806cb792363c5c87
Bug: 40932006
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5703551
Reviewed-by: Aaron Leventhal aleventhal@chromium.org
Reviewed-by: Joey Arhar jarhar@chromium.org
Commit-Queue: Di Zhang dizhangg@chromium.org
Cr-Commit-Position: refs/heads/main@{#1327591}