Reverting sharing of descriptor arrays:

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 7c03a49e8536a4ace1e0e4aaa73eddeb22031a08..a9a90bdf64d38d295383bc2731a56a1869476702 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -1548,8 +1548,7 @@ class MarkCompactMarkingVisitor::ObjectStatsTracker<
     Map* map_obj = Map::cast(obj);
     ASSERT(map->instance_type() == MAP_TYPE);
     DescriptorArray* array = map_obj->instance_descriptors();
-    if (map_obj->owns_descriptors() &&
-        array != heap->empty_descriptor_array()) {
+    if (array != heap->empty_descriptor_array()) {
       int fixed_array_size = array->Size();
       heap->RecordObjectStats(FIXED_ARRAY_TYPE,
                               DESCRIPTOR_ARRAY_SUB_TYPE,
@@ -1943,10 +1942,10 @@ void Marker<T>::MarkTransitionArray(TransitionArray* transitions) {
   if (!base_marker()->MarkObjectWithoutPush(transitions)) return;
   Object** transitions_start = transitions->data_start();
 
-  // We don't have to record the descriptors_pointer slot since the cell space
-  // is not compacted.
-  JSGlobalPropertyCell* descriptors_cell = transitions->descriptors_pointer();
-  base_marker()->MarkObjectAndPush(descriptors_cell);
+  DescriptorArray* descriptors = transitions->descriptors();
+  base_marker()->MarkObjectAndPush(descriptors);
+  mark_compact_collector()->RecordSlot(
+      transitions_start, transitions->GetDescriptorsSlot(), descriptors);
 
   if (transitions->HasPrototypeTransitions()) {
     // Mark prototype transitions array but don't push it into marking stack.