Couple the enumeration index of a property to the size of the descriptor array where it first appea…

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 9726f1af12a6b4651a94551548d22607fbe7c5e5..231ddbb6f6fee32c5722331f8479b1788ee4a34b 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -5801,7 +5801,7 @@ MaybeObject* DescriptorArray::Allocate(int number_of_descriptors,
     if (!maybe_array->To(&result)) return maybe_array;
   }
 
-  result->set(kLastAddedIndex, Smi::FromInt(-1));
+  result->set(kLastAddedIndex, Smi::FromInt(kNoneAdded));
   result->set(kTransitionsIndex, Smi::FromInt(0));
   return result;
 }
@@ -5928,7 +5928,8 @@ MaybeObject* DescriptorArray::CopyAdd(Descriptor* descriptor) {
 
   FixedArray::WhitenessWitness witness(new_descriptors);
 
-  descriptor->SetEnumerationIndex(NextEnumerationIndex());
+  ASSERT(new_size == NextEnumerationIndex());
+  descriptor->SetEnumerationIndex(new_size);
 
   // Copy the descriptors, inserting or replacing a descriptor.
   int insertion_index = -1;
@@ -6035,18 +6036,20 @@ void DescriptorArray::SortUnchecked(const WhitenessWitness& witness) {
     }
   }
 
-  int last_enum_index = -1;
-  int last_added = -1;
+  ASSERT(LastAdded() == kNoneAdded);
   for (int i = 0; i < len; ++i) {
     int current_enum = GetDetails(i).index();
-    if (current_enum > last_enum_index) {
-      last_added = i;
-      last_enum_index = current_enum;
+    ASSERT(current_enum <= len);
+
+    if (current_enum == len) {
+      ASSERT(LastAdded() == kNoneAdded);
+      SetLastAdded(i);
+#ifndef DEBUG
+      return;
+#endif
     }
   }
-  SetLastAdded(last_added);
-
-  ASSERT(LastAdded() != -1);
+  ASSERT(LastAdded() != kNoneAdded);
 }