[A11y] Create AXMenuList even for <select size=1> in a canvas

Bug: none
Change-Id: Ic6127e95d3fb276e0349c95982e2f44b6880ebe6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5405452


Commit-Queue: Joey Arhar <jarhar@chromium.org>
Reviewed-by: Joey Arhar <jarhar@chromium.org>
Auto-Submit: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1280321}