Fixing deleted alertKey in revision-range.
Fixing deleted alertKey in revision-range.

When switching the revision-range portion of the alerts-table, I accidentally deleted the part that sets the alert-key. Thus the links on the alerts-table were broken. This CL adds it back in.

Review-Url: https://codereview.chromium.org/2694363002

benschmaus/catapult,sahiljain/catapult,sahiljain/catapult,sahiljain/catapult,catapult-project/catapult,sahiljain/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult,benschmaus/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,catapult-project/catapult,benschmaus/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult,benschmaus/catapult,catapult-project/catapult,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult