[serializer] make snapshot reproducible.

src/snapshot/mksnapshot.cc

Index: src/snapshot/mksnapshot.cc
diff --git a/src/snapshot/mksnapshot.cc b/src/snapshot/mksnapshot.cc
index c5a3509186ececcf63865ecd6d983b42b9207824..689d9a92528417eb4806d65b622aeedc8830eb41 100644
--- a/src/snapshot/mksnapshot.cc
+++ b/src/snapshot/mksnapshot.cc
@@ -139,7 +139,8 @@ int main(int argc, char** argv) {
   // By default, log code create information in the snapshot.
   i::FLAG_log_code = true;
   i::FLAG_logfile_per_isolate = false;
-
+  // Make mksnapshot runs predictable to create reproducible snapshots.
+  i::FLAG_predictable = true;
   // Print the usage if an error occurs when parsing the command line
   // flags or if the help flag is set.
   int result = i::FlagList::SetFlagsFromCommandLine(&argc, argv, true);