Symbols for type cells.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 42e56ca1eb9e2bb40498d9ea2d341c71a67f6b4e..a359a0c9ffb02c933a6cba876dac1e72a820a0ec 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -3309,6 +3309,18 @@ bool Heap::CreateInitialObjects() {
   Symbol::cast(obj)->set_is_private(true);
   set_elements_transition_symbol(Symbol::cast(obj));
 
+  { MaybeObject* maybe_obj = AllocateSymbol();
+    if (!maybe_obj->ToObject(&obj)) return false;
+  }
+  Symbol::cast(obj)->set_is_private(true);
+  set_uninitialized_symbol(Symbol::cast(obj));
+
+  { MaybeObject* maybe_obj = AllocateSymbol();
+    if (!maybe_obj->ToObject(&obj)) return false;
+  }
+  Symbol::cast(obj)->set_is_private(true);
+  set_megamorphic_symbol(Symbol::cast(obj));
+
   { MaybeObject* maybe_obj = SeededNumberDictionary::Allocate(this, 0, TENURED);
     if (!maybe_obj->ToObject(&obj)) return false;
   }