Make stylesheet handling a bit more normative.
Make stylesheet handling a bit more normative.

TBR=nduca@chromium.org

Review URL: https://codereview.appspot.com/6490048
benschmaus/catapult,dstockwell/catapult,zeptonaut/catapult,danbeam/catapult,catapult-project/catapult,catapult-project/catapult-csm,benschmaus/catapult,modulexcite/catapult,dstockwell/catapult,vmpstr/trace-viewer,danbeam/catapult,catapult-project/catapult,danbeam/catapult,scottmcmaster/catapult,sahiljain/catapult,scottmcmaster/catapult,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult,catapult-project/catapult,modulexcite/catapult,SummerLW/Perf-Insight-Report,vmpstr/trace-viewer,catapult-project/catapult-csm,modulexcite/catapult,zeptonaut/catapult,sahiljain/catapult,SummerLW/Perf-Insight-Report,sahiljain/catapult,catapult-project/catapult-csm,SummerLW/Perf-Insight-Report,0x90sled/catapult,SummerLW/Perf-Insight-Report,dstockwell/catapult,zeptonaut/catapult,benschmaus/catapult,sahiljain/catapult,danbeam/catapult,benschmaus/catapult,0x90sled/catapult,benschmaus/catapult,SummerLW/Perf-Insight-Report,benschmaus/catapult,catapult-project/catapult-csm,benschmaus/catapult,vmpstr/trace-viewer,sahiljain/catapult,catapult-project/catapult,dstockwell/catapult,catapult-project/catapult,catapult-project/catapult-csm,SummerLW/Perf-Insight-Report,0x90sled/catapult,catapult-project/catapult-csm,scottmcmaster/catapult,catapult-project/catapult