Only mark the descriptor that is valid for the map in question. If this map

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 647e2861c6b5c7505d41b9af21504e80f3aea2bc..8ee3656b23841f03c2721cf89878a25239cea87f 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -7643,11 +7643,12 @@ static void TrimDescriptorArray(Heap* heap,
                                 Map* map,
                                 DescriptorArray* descriptors,
                                 int number_of_own_descriptors) {
-  int number_of_descriptors = descriptors->number_of_descriptors();
+  int number_of_descriptors = descriptors->number_of_descriptors_storage();
   int to_trim = number_of_descriptors - number_of_own_descriptors;
-  if (to_trim <= 0) return;
+  if (to_trim == 0) return;
 
-  RightTrimFixedArray<FROM_GC>(heap, descriptors, to_trim);
+  RightTrimFixedArray<FROM_GC>(
+      heap, descriptors, to_trim * DescriptorArray::kDescriptorSize);
   descriptors->SetNumberOfDescriptors(number_of_own_descriptors);
 
   if (descriptors->HasEnumCache()) TrimEnumCache(heap, map, descriptors);