Fix releasing focus on scripting control
Fix releasing focus on scripting control

For some reason the previous workaround for crbug.com/89026 stopped
working, so instead remove and insert the prompt element from the DOM to
ensure focus is dropped correctly.

TEST=Open Trace Viewer, press ` twice to open and close the console,
     then navigate the trace with the A/D keys a few times => A/D
     characters should not end up in the console.

R=dsinclair@chromium.org

Review URL: https://codereview.appspot.com/216600043

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