[api] Bring back finalizers on global handles

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 7952fc9bd1e1b9b9cb5d85c920dee149582ff4ad..4db7c43de7d4cc989a23bce158c6741b553f3844 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -480,9 +480,12 @@ class WeakCallbackData {
 template <class T>
 using PhantomCallbackData = WeakCallbackInfo<T>;
 
-
-enum class WeakCallbackType { kParameter, kInternalFields };
-
+// kParameter will pass a void* parameter back to the callback, kInternalFields
+// will pass the first two internal fields back to the callback, kFinalizer
+// will pass a void* parameter back, but is invoked before the object is
+// actually collected, so it can be resurrected. In the last case, it is not
+// possible to request a second pass callback.
+enum class WeakCallbackType { kParameter, kInternalFields, kFinalizer };
 
 /**
  * An object reference that is independent of any handle scope.  Where