Revert of Only use FreeSpace objects in the free list.

src/heap/spaces-inl.h

Index: src/heap/spaces-inl.h
diff --git a/src/heap/spaces-inl.h b/src/heap/spaces-inl.h
index cfa23255c41c10b09de336b5bce3198764bd1186..9cb292e3df4adfdf53e3b716560df5399479cc43 100644
--- a/src/heap/spaces-inl.h
+++ b/src/heap/spaces-inl.h
@@ -305,6 +305,14 @@
   return ObjectSizeFor(heap()->isolate()->memory_allocator()->Available());
 }
 
+
+bool FreeListNode::IsFreeListNode(HeapObject* object) {
+  Map* map = object->map();
+  Heap* heap = object->GetHeap();
+  return map == heap->raw_unchecked_free_space_map() ||
+         map == heap->raw_unchecked_one_pointer_filler_map() ||
+         map == heap->raw_unchecked_two_pointer_filler_map();
+}
 }
 }  // namespace v8::internal