Ensure blink accessibility state remains in sync for listbox options

There were some situations where list box options were not being
deselected when the selection moved to a different option. This had
the affect of screen readers getting the information which wasn't
correct. This fixes that by marking the listbox as dirty to ensure the
list box options remain in sync when the selection changes.

Bug: 980368
Change-Id: Icff41b23218ce2db7ac5437be642371894a92b07
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1821902
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Jessica Tallon <jtallon@igalia.com>
Cr-Commit-Position: refs/heads/master@{#703423}
8 files changed