Add a new weak handle callback that passes an Isolate to an embedder

src/global-handles.h

Index: src/global-handles.h
diff --git a/src/global-handles.h b/src/global-handles.h
index 7808d16a03f6e930829671550c5a7bd56b2c7518..98245a8745739f065ccf1599c6435e6d4ebc86f3 100644
--- a/src/global-handles.h
+++ b/src/global-handles.h
@@ -129,6 +129,9 @@ class GlobalHandles {
   void MakeWeak(Object** location,
                 void* parameter,
                 WeakReferenceCallback callback);
+  void MakeWeak(Object** location,
+                void* parameter,
+                WeakenedReferenceCallback callback);
 
   static void SetWrapperClassId(Object** location, uint16_t class_id);
   static uint16_t GetWrapperClassId(Object** location);
@@ -183,10 +186,6 @@ class GlobalHandles {
   // Iterates over all weak roots in heap.
   void IterateWeakRoots(ObjectVisitor* v);
 
-  // Iterates over weak roots that are bound to a given callback.
-  void IterateWeakRoots(WeakReferenceGuest f,
-                        WeakReferenceCallback callback);
-
   // Find all weak handles satisfying the callback predicate, mark
   // them as pending.
   void IdentifyWeakHandles(WeakSlotCallback f);