Reset code age on the cloned code when serializing.

R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/757983002

Cr-Commit-Position: refs/heads/master@{#25498}

src/objects.cc

@@ -10753,9 +10753,9 @@ static Code::Age EffectiveAge(Code::Age age) {
 }
 
 
-void Code::MakeYoung() {
+void Code::MakeYoung(Isolate* isolate) {
   byte* sequence = FindCodeAgeSequence();
-  if (sequence != NULL) MakeCodeAgeSequenceYoung(sequence, GetIsolate());
+  if (sequence != NULL) MakeCodeAgeSequenceYoung(sequence, isolate);
 }
 
 

src/objects.h

@@ -5315,7 +5315,7 @@ class Code: public HeapObject {
   // compilation stub.
   static void MakeCodeAgeSequenceYoung(byte* sequence, Isolate* isolate);
   static void MarkCodeAsExecuted(byte* sequence, Isolate* isolate);
-  void MakeYoung();
+  void MakeYoung(Isolate* isolate);
   void MakeOlder(MarkingParity);
   static bool IsYoungSequence(Isolate* isolate, byte* sequence);
   bool IsOld();

src/serialize.cc

@@ -1874,6 +1874,8 @@ int Serializer::ObjectSerializer::OutputRawData(
     // To make snapshots reproducible, we need to wipe out all pointers in code.
     if (code_object_) {
       Code* code = CloneCodeObject(object_);
+      // Code age headers are not serializable.
+      code->MakeYoung(serializer_->isolate());
       WipeOutRelocations(code);
       // We need to wipe out the header fields *after* wiping out the
       // relocations, because some of these fields are needed for the latter.
@@ -2049,7 +2051,6 @@ void CodeSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
         if (code_object != main_code_ && !FLAG_serialize_inner) {
           SerializeBuiltin(Builtins::kCompileLazy, how_to_code, where_to_point);
         } else {
-          code_object->MakeYoung();
           SerializeGeneric(code_object, how_to_code, where_to_point);
         }
         return;