Fix brushing under/overflow bins in histogram-span
Fix brushing under/overflow bins in histogram-span

Review-Url: https://codereview.chromium.org/2155713003

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