[annotee] Make sure step's EndTime is set when a step is auto-closed.
[annotee] Make sure step's EndTime is set when a step is auto-closed.

R=40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org
BUG=860508

Change-Id: If6a046d4242546a63cb4fe76f97ef37820436898
Reviewed-on: https://chromium-review.googlesource.com/1141154
Commit-Queue: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go