Add code age subtype tracking to --track-gc-object-stats

src/x64/codegen-x64.cc

Index: src/x64/codegen-x64.cc
diff --git a/src/x64/codegen-x64.cc b/src/x64/codegen-x64.cc
index 2002608429fb50dfd447919f3593fc00b0d09836..8ef577fea4848807cd4d8b44044ecf7147fd24c2 100644
--- a/src/x64/codegen-x64.cc
+++ b/src/x64/codegen-x64.cc
@@ -706,7 +706,7 @@ bool Code::IsYoungSequence(byte* sequence) {
 void Code::GetCodeAgeAndParity(byte* sequence, Age* age,
                                MarkingParity* parity) {
   if (IsYoungSequence(sequence)) {
-    *age = kNoAge;
+    *age = kNoAgeCodeAge;
     *parity = NO_MARKING_PARITY;
   } else {
     sequence++;  // Skip the kCallOpcode byte
@@ -724,7 +724,7 @@ void Code::PatchPlatformCodeAge(Isolate* isolate,
                                 MarkingParity parity) {
   uint32_t young_length;
   byte* young_sequence = GetNoCodeAgeSequence(&young_length);
-  if (age == kNoAge) {
+  if (age == kNoAgeCodeAge) {
     CopyBytes(sequence, young_sequence, young_length);
     CPU::FlushICache(sequence, young_length);
   } else {