A64: Synchronize with r18084.

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 2d2e112bff7ecddf5c7df8aab4b1665ec921c44f..5d9f993b122e1131e2a3d2f87b5af322ffa38141 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -627,10 +627,6 @@ DEFINE_int(hash_seed, 0,
 DEFINE_bool(profile_deserialization, false,
             "Print the time it takes to deserialize the snapshot.")
 
-// v8.cc
-DEFINE_bool(preemption, false,
-            "activate a 100ms timer that switches between V8 threads")
-
 // Regexp
 DEFINE_bool(regexp_optimization, true, "generate optimized regexp code")
 
@@ -805,6 +801,10 @@ DEFINE_bool(log_regexp, false, "Log regular expression execution.")
 DEFINE_string(logfile, "v8.log", "Specify the name of the log file.")
 DEFINE_bool(logfile_per_isolate, true, "Separate log files for each isolate.")
 DEFINE_bool(ll_prof, false, "Enable low-level linux profiler.")
+DEFINE_bool(perf_basic_prof, false,
+            "Enable perf linux profiler (basic support).")
+DEFINE_bool(perf_jit_prof, false,
+            "Enable perf linux profiler (experimental annotate support).")
 DEFINE_string(gc_fake_mmap, "/tmp/__v8_gc__",
               "Specify the name of the file for fake gc mmap used in ll_prof")
 DEFINE_bool(log_internal_timer_events, false, "Time internal events.")