webui: Hide menu separators when all items below it until the next separator are hidden

Bug: 878324
Change-Id: I449362cec69c11182f9d13cdbd4b40410e3b027f
Reviewed-on: https://chromium-review.googlesource.com/c/1304178
Reviewed-by: Naoki Fukino <fukino@chromium.org>
Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603425}
1 file changed