Add flag to trace object groups

src/global-handles.h

Index: src/global-handles.h
diff --git a/src/global-handles.h b/src/global-handles.h
index 7047d8ca015d7344022cb61e4fe4d18308803a8c..e1722d8e9914b41a30f701e077f0c0b27dcb398b 100644
--- a/src/global-handles.h
+++ b/src/global-handles.h
@@ -242,6 +242,9 @@ class GlobalHandles {
   // can be skipped and false otherwise.
   bool IterateObjectGroups(ObjectVisitor* v, WeakSlotCallbackWithHeap can_skip);
 
+  // Print all objects in object groups
+  void PrintObjectGroups();
+
   // Add an object group.
   // Should be only used in GC callback function before a collection.
   // All groups are destroyed after a garbage collection.