Provide private symbols through internal APIs

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index fa358c53929127218fbd4fd719d5bec8d3bab3b0..1d87c4d1ac7b85a450383aa5f82daa3dfb914477 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -3279,12 +3279,12 @@ bool Heap::CreateInitialObjects() {
   }
   set_observation_state(JSObject::cast(obj));
 
-  { MaybeObject* maybe_obj = AllocateSymbol();
+  { MaybeObject* maybe_obj = AllocatePrivate();
     if (!maybe_obj->ToObject(&obj)) return false;
   }
   set_frozen_symbol(Symbol::cast(obj));
 
-  { MaybeObject* maybe_obj = AllocateSymbol();
+  { MaybeObject* maybe_obj = AllocatePrivate();
     if (!maybe_obj->ToObject(&obj)) return false;
   }
   set_elements_transition_symbol(Symbol::cast(obj));
@@ -3295,7 +3295,7 @@ bool Heap::CreateInitialObjects() {
   SeededNumberDictionary::cast(obj)->set_requires_slow_elements();
   set_empty_slow_element_dictionary(SeededNumberDictionary::cast(obj));
 
-  { MaybeObject* maybe_obj = AllocateSymbol();
+  { MaybeObject* maybe_obj = AllocatePrivate();
     if (!maybe_obj->ToObject(&obj)) return false;
   }
   set_observed_symbol(Symbol::cast(obj));
@@ -5596,7 +5596,21 @@ MaybeObject* Heap::AllocateSymbol() {
       Name::kIsNotArrayIndexMask | (hash << Name::kHashShift));
   Symbol::cast(result)->set_name(undefined_value());
 
-  ASSERT(result->IsSymbol());
+  ASSERT(result->IsSymbol() && !result->IsPrivate());
+  return result;
+}
+
+
+MaybeObject* Heap::AllocatePrivate() {
+  STATIC_ASSERT(Private::kSize == Symbol::kSize);
+  MaybeObject* maybe = AllocateSymbol();
+  Symbol* result;
+  if (!maybe->To(&result)) return maybe;
+  maybe = AllocateBox(undefined_value(), TENURED);
+  Box* box;
+  if (!maybe->To(&box)) return maybe;
+  result->set_name(box);  // Marker for private.
+  ASSERT(result->IsPrivate());
   return result;
 }