Upgrade V8 to 5.1.281.57  DO NOT MERGE

FPIIM-449

Change-Id: Id981b686b4d587ac31697662eb98bb34be42ad90
(cherry picked from commit 3b9bc31999c9787eb726ecdbfd5796bfdec32a18)
diff --git a/src/log-utils.h b/src/log-utils.h
index 7621668..3e70a96 100644
--- a/src/log-utils.h
+++ b/src/log-utils.h
@@ -30,7 +30,7 @@
   static bool InitLogAtStart() {
     return FLAG_log || FLAG_log_api || FLAG_log_code || FLAG_log_gc ||
            FLAG_log_handles || FLAG_log_suspect || FLAG_log_regexp ||
-           FLAG_ll_prof || FLAG_perf_basic_prof ||
+           FLAG_ll_prof || FLAG_perf_basic_prof || FLAG_perf_prof ||
            FLAG_log_internal_timer_events || FLAG_prof_cpp;
   }