Added zone tracing

src/zone/accounting-allocator.h

Index: src/zone/accounting-allocator.h
diff --git a/src/zone/accounting-allocator.h b/src/zone/accounting-allocator.h
index b8ca5471cecd46138510874f8cf74da05f332b90..f519c45db33637bbc78bbe3c0539269b17ab30db 100644
--- a/src/zone/accounting-allocator.h
+++ b/src/zone/accounting-allocator.h
@@ -35,6 +35,9 @@ class V8_EXPORT_PRIVATE AccountingAllocator {
 
   void MemoryPressureNotification(MemoryPressureLevel level);
 
+  virtual void ZoneCreation(const Zone* zone) {}
+  virtual void ZoneDestruction(const Zone* zone) {}
+
  private:
   static const uint8_t kMinSegmentSizePower = 13;
   static const uint8_t kMaxSegmentSizePower = 18;