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

src/v8-counters.cc

Index: src/v8-counters.cc
diff --git a/src/v8-counters.cc b/src/v8-counters.cc
index 6711c80203e1cc766833ea811f9fdbf7ae5e77bd..a0c3ebd07c45ce7738dbcff4f3ed07b7e54f7053 100644
--- a/src/v8-counters.cc
+++ b/src/v8-counters.cc
@@ -76,6 +76,14 @@ Counters::Counters(Isolate* isolate) {
         StatsCounter(isolate, "c:" "V8.SizeOf_FIXED_ARRAY-" #name);
     FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(SC)
 #undef SC
+
+#define SC(name) \
+    count_of_CODE_AGE_##name##_ = \
+        StatsCounter(isolate, "c:" "V8.CountOf_CODE_AGE-" #name); \
+    size_of_CODE_AGE_##name##_ = \
+        StatsCounter(isolate, "c:" "V8.SizeOf_CODE_AGE-" #name);
+    CODE_AGE_LIST_WITH_NO_AGE(SC)
+#undef SC
 }