Add zero interval duration test.
Add zero interval duration test.

This tests that a find on the interval tree with a start equal to the end
will find results.

TBR=nduca@chromium.org

Review URL: https://codereview.appspot.com/221800043

SummerLW/Perf-Insight-Report,scottmcmaster/catapult,danbeam/catapult,benschmaus/catapult,0x90sled/catapult,catapult-project/catapult,benschmaus/catapult,sahiljain/catapult,SummerLW/Perf-Insight-Report,vmpstr/trace-viewer,catapult-project/catapult,0x90sled/catapult,benschmaus/catapult,dstockwell/catapult,catapult-project/catapult-csm,modulexcite/catapult,sahiljain/catapult,benschmaus/catapult,0x90sled/catapult,SummerLW/Perf-Insight-Report,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,scottmcmaster/catapult,dstockwell/catapult,catapult-project/catapult-csm,SummerLW/Perf-Insight-Report,vmpstr/trace-viewer,dstockwell/catapult,modulexcite/catapult,sahiljain/catapult,benschmaus/catapult,sahiljain/catapult,modulexcite/catapult,catapult-project/catapult,zeptonaut/catapult,catapult-project/catapult-csm,catapult-project/catapult,benschmaus/catapult,SummerLW/Perf-Insight-Report,vmpstr/trace-viewer,catapult-project/catapult-csm,zeptonaut/catapult,zeptonaut/catapult,SummerLW/Perf-Insight-Report,danbeam/catapult,catapult-project/catapult,catapult-project/catapult,danbeam/catapult,scottmcmaster/catapult,catapult-project/catapult,danbeam/catapult,benschmaus/catapult,sahiljain/catapult,dstockwell/catapult,catapult-project/catapult-csm