Pass --nologfile-per-isolate to d8 in plot-timer-events calibration code

tools/plot-timer-events

 #!/bin/sh
 
 # find the name of the log file to process, it must not start with a dash.
 log_file="v8.log"
 for arg in "$@"
 do
   if ! expr "X${arg}" : "^X-" > /dev/null; then
     log_file=${arg}
   fi
 done
@@ skipping 19 matching lines @@
   echo "d8 shell not found in $D8_PATH"
   echo "To build, execute 'make native' from the V8 directory"
   exit 1
 fi
 
 if [[ "$@" != *--distortion* ]]; then
   # Try to find out how much the instrumentation overhead is.
   calibration_log=calibration.log
   calibration_script="for (var i = 0; i < 1000000; i++) print();"
 
-  $d8_exec --nocrankshaft --prof --logfile $calibration_log \
-       --log-timer-events -e "$calibration_script" > /dev/null
+  $d8_exec --nocrankshaft --prof --log-timer-events \
+       --logfile $calibration_log --nologfile-per-isolate \
+       -e "$calibration_script" > /dev/null
   t_1_start=`grep "timer-event-start,\"V8.Execute\"" $calibration_log  \
        | tail -n1 | awk -F, '{print $3}'`
   t_1_end=`grep "timer-event-end,\"V8.Execute\"" $calibration_log  \
        | tail -n1 | awk -F, '{print $3}'`
   n_1=`grep "timer-event\|tick" $calibration_log  | wc -l`
 
-  $d8_exec --nocrankshaft --prof --logfile $calibration_log \
-       --log-internal-timer-events -e "$calibration_script" > /dev/null
+  $d8_exec --nocrankshaft --prof --log-internal-timer-events \
+       --logfile $calibration_log --nologfile-per-isolate \
+       -e "$calibration_script" > /dev/null
   t_2_start=`grep "timer-event-start,\"V8.Execute\"" $calibration_log  \
        | tail -n1 | awk -F, '{print $3}'`
   t_2_end=`grep "timer-event-end,\"V8.Execute\"" $calibration_log  \
        | tail -n1 | awk -F, '{print $3}'`
   n_2=`grep "timer-event\|tick" $calibration_log  | wc -l`
 
   rm $calibration_log
 
   # Overhead in picoseconds.
   options=--distortion=
@@ skipping 10 matching lines @@
     -- $@ $options 2>/dev/null > timer-events.plot
 
 success=$?
 if [[ $success != 0 ]] ; then
     cat timer-events.plot
 else
     cat timer-events.plot | gnuplot > timer-events.png
 fi
 
 rm -f timer-events.plot