collect phantom handle data before it gets overwritten

src/global-handles.h

Index: src/global-handles.h
diff --git a/src/global-handles.h b/src/global-handles.h
index cb5619ffbe0c3c2a42589230be984b883e26352a..6724847303d4188ffdab4fb31c859a9b85d2a410 100644
--- a/src/global-handles.h
+++ b/src/global-handles.h
@@ -162,14 +162,6 @@ class GlobalHandles {
     return number_of_global_handles_;
   }
 
-  // Collect up data for the weak handle callbacks after GC has completed, but
-  // before memory is reclaimed.
-  void CollectAllPhantomCallbackData();
-
-  // Collect up data for the weak handle callbacks referenced by young
-  // generation after GC has completed, but before memory is reclaimed.
-  void CollectYoungPhantomCallbackData();
-
   // Clear the weakness of a global handle.
   static void* ClearWeakness(Object** location);