Introduce instance type for transition arrays.

src/heap/objects-visiting-inl.h

Index: src/heap/objects-visiting-inl.h
diff --git a/src/heap/objects-visiting-inl.h b/src/heap/objects-visiting-inl.h
index b6c72185c65d54a558396debb1de11c5d3b18320..2d03c125eb15942110ff192586d4c20e26d4c36a 100644
--- a/src/heap/objects-visiting-inl.h
+++ b/src/heap/objects-visiting-inl.h
@@ -179,6 +179,8 @@ void StaticMarkingVisitor<StaticVisitor>::Initialize() {
 
   table_.Register(kVisitWeakCell, &VisitWeakCell);
 
+  table_.Register(kVisitTransitionArray, &VisitTransitionArray);
+
   table_.template RegisterSpecializations<DataObjectVisitor, kVisitDataObject,
                                           kVisitDataObjectGeneric>();
 
@@ -342,6 +344,25 @@ void StaticMarkingVisitor<StaticVisitor>::VisitWeakCell(Map* map,
 
 
 template <typename StaticVisitor>
+void StaticMarkingVisitor<StaticVisitor>::VisitTransitionArray(
+    Map* map, HeapObject* object) {
+  typedef FlexibleBodyVisitor<StaticVisitor, TransitionArray::BodyDescriptor,
+                              int> TransitionArrayBodyVisitor;
+  TransitionArray* array = TransitionArray::cast(object);
+  // Enqueue the array in linked list of encountered transition arrays if it is
+  // not already in the list.
+  if (array->next_link()->IsUndefined()) {
+    Heap* heap = map->GetHeap();
+    array->set_next_link(heap->encountered_transition_arrays(),
+                         UPDATE_WEAK_WRITE_BARRIER);
+    heap->set_encountered_transition_arrays(array);
+  }
+  // TODO(ulan): Move MarkTransitionArray logic here.
+  TransitionArrayBodyVisitor::Visit(map, object);
+}
+
+
+template <typename StaticVisitor>
 void StaticMarkingVisitor<StaticVisitor>::VisitAllocationSite(
     Map* map, HeapObject* object) {
   Heap* heap = map->GetHeap();