vinn: Modifies the update_v8 script to work on Windows
vinn: Modifies the update_v8 script to work on Windows

BUG=catapult:#1929

Review URL: https://codereview.chromium.org/1703423002

SummerLW/Perf-Insight-Report,SummerLW/Perf-Insight-Report,catapult-project/catapult-csm,sahiljain/catapult,catapult-project/catapult-csm,SummerLW/Perf-Insight-Report,benschmaus/catapult,benschmaus/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult,catapult-project/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult,benschmaus/catapult,SummerLW/Perf-Insight-Report,benschmaus/catapult,catapult-project/catapult-csm,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult,sahiljain/catapult,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult-csm,sahiljain/catapult,sahiljain/catapult,catapult-project/catapult,catapult-project/catapult-csm