Merge verbatim descriptors from other (the descriptor of the map being updated) rather than this (d…

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 2b36397dc049dcc0411ac68f94f00f4d3e72a959..9d41c3ce7b5a357ba1b19afeb45b2f5256972544 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -7817,7 +7817,7 @@ MaybeObject* DescriptorArray::Merge(int verbatim,
   int current_offset = 0;
   for (descriptor = 0; descriptor < verbatim; descriptor++) {
     if (GetDetails(descriptor).type() == FIELD) current_offset++;
-    result->CopyFrom(descriptor, this, descriptor, witness);
+    result->CopyFrom(descriptor, other, descriptor, witness);
   }
 
   // |verbatim| -> |valid|