WebUI Tab Strip: Close edit dialog for groups when group is removed

Bug: 1228557
Change-Id: Ibe6a0cf0ea0449d5d6c6e5d7b58828932dac7ac5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3057297


Commit-Queue: John Lee <johntlee@chromium.org>
Reviewed-by: Charlene Yan <cyan@chromium.org>
Reviewed-by: Thomas Lukaszewicz <tluk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#908595}