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

tools/plot-timer-events

Index: tools/plot-timer-events
diff --git a/tools/plot-timer-events b/tools/plot-timer-events
index 8db067d5f12c800df35dc5c4e6cffbf3743150d0..c14a909bf464e031255eda5c959bea32f735f1d6 100755
--- a/tools/plot-timer-events
+++ b/tools/plot-timer-events
@@ -37,16 +37,18 @@ if [[ "$@" != *--distortion* ]]; then
   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  \