[heap] Optimize migration of objects

src/heap/mark-compact.h

Index: src/heap/mark-compact.h
diff --git a/src/heap/mark-compact.h b/src/heap/mark-compact.h
index a1be7b8fca365df004f9d83afc49a49da14c718e..3bcc0286ef033cb3c397686b317facec25259152 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -485,9 +485,6 @@ class MarkCompactCollector {
   void UpdateSlots(SlotsBuffer* buffer);
   void UpdateSlotsRecordedIn(SlotsBuffer* buffer);
 
-  void MigrateObject(HeapObject* dst, HeapObject* src, int size,
-                     AllocationSpace to_old_space);
-
   void InvalidateCode(Code* code);
 
   void ClearMarkbits();