Do not follow accessor map transitions when marking descriptor arrays.

src/mark-compact-inl.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 48 matching lines @@
 void MarkCompactCollector::MarkObject(HeapObject* obj, MarkBit mark_bit) {
   ASSERT(Marking::MarkBitFrom(obj) == mark_bit);
   if (!mark_bit.Get()) {
     mark_bit.Set();
     MemoryChunk::IncrementLiveBytesFromGC(obj->address(), obj->Size());
     ProcessNewlyMarkedObject(obj);
   }
 }
 
 
+bool MarkCompactCollector::MarkObjectWithoutPush(HeapObject* object) {
+  MarkBit mark = Marking::MarkBitFrom(object);
+  bool old_mark = mark.Get();
+  if (!old_mark) SetMark(object, mark);
+  return old_mark;
+}
+
+
+void MarkCompactCollector::MarkObjectAndPush(HeapObject* object) {
+  if (!MarkObjectWithoutPush(object)) marking_deque_.PushBlack(object);
+}
+
+
 void MarkCompactCollector::SetMark(HeapObject* obj, MarkBit mark_bit) {
   ASSERT(!mark_bit.Get());
   ASSERT(Marking::MarkBitFrom(obj) == mark_bit);
   mark_bit.Set();
   MemoryChunk::IncrementLiveBytesFromGC(obj->address(), obj->Size());
   if (obj->IsMap()) {
     ClearCacheOnMap(Map::cast(obj));
   }
 }
 
@@ skipping 17 matching lines @@
                             SlotsBuffer::FAIL_ON_OVERFLOW)) {
       EvictEvacuationCandidate(object_page);
     }
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_MARK_COMPACT_INL_H_