[Tracing] Use TracingCategoryObserver in gc statistics

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index b7a5b2e4ec45e1642a6ad578e9f98604f490d806..4f9dc963234a27e895f620ebf4811d8a5c2eb138 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -8063,7 +8063,7 @@ size_t Isolate::NumberOfTrackedHeapObjectTypes() {
 bool Isolate::GetHeapObjectStatisticsAtLastGC(
     HeapObjectStatistics* object_statistics, size_t type_index) {
   if (!object_statistics) return false;
-  if (!i::FLAG_track_gc_object_stats) return false;
+  if (V8_LIKELY(!i::FLAG_gc_stats)) return false;
 
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
   i::Heap* heap = isolate->heap();