Stop serializing HistogramBin ranges.
Stop serializing HistogramBin ranges.

Currently, histogram bin boundaries are serialized 3 times: once in
Histogram.asDict(), and twice for the two bins on either side of the boundary.
Only the first is necessary.

Review-Url: https://codereview.chromium.org/2339993002

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