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 df4739ea04d9b1b271705ae2922ac14ecc6388fb..9c0159d2202db81bb5b771f711d0427907c69b2e 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -1940,10 +1940,10 @@ void Marker<T>::MarkTransitionArray(TransitionArray* transitions) {
   if (!base_marker()->MarkObjectWithoutPush(transitions)) return;
   Object** transitions_start = transitions->data_start();
 
-  DescriptorArray* descriptors = transitions->descriptors();
-  base_marker()->MarkObjectAndPush(descriptors);
-  mark_compact_collector()->RecordSlot(
-      transitions_start, transitions->GetDescriptorsSlot(), descriptors);
+  // 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);
 
   if (transitions->HasPrototypeTransitions()) {
     // Mark prototype transitions array but don't push it into marking stack.