[tracing] Fix crash in getObjectInstanceColor due to typo
[tracing] Fix crash in getObjectInstanceColor due to typo

I typo'ed a variable when rebasing one of my CLs.

BUG=catapult:#3526
BUG=chromium:715512

Review-Url: https://codereview.chromium.org/2841243003

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