ksv: Add a11y name for special chars

Certain punctuation isn't verbalized by ChromeVox, i.e. period, comma,
semicolon, hyphen or brackets. So, whenever one of these is used in a
keyboard shortcut, it just will speak "Ctrl plus [silence]" so you don't
actually hear what the correct command is.
This patch adds special labels mapping to those chars.

Bug: 974799
Test: manual
Change-Id: I548c9e0a179245c42e40ae63b1b457a0c9cba3cb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1674634
Commit-Queue: Tao Wu <wutao@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672178}
4 files changed