GitLab

Make dots clickable and add proper aria-labels and role.
Add aria-label to slides for better spoken feedback.

Bug: 1125620
Change-Id: I6f20d4b1e3293aa89c81d4a6da960b6fd0fb0b6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2396084
Commit-Queue: Roman Aleksandrov <raleksandrov@google.com>
Reviewed-by: Denis Kuznetsov [CET] <antrim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805876}