Move hash code from hidden string to a private symbol

src/factory.cc

Index: src/factory.cc
diff --git a/src/factory.cc b/src/factory.cc
index 59ab64dbe5d723516e5e13a0f6ecff6005adccfc..fc8919c648dcee78318d29611a7fa6d100daafc2 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -705,10 +705,15 @@ Handle<Symbol> Factory::NewPrivateSymbol() {
 }
 
 
-Handle<Symbol> Factory::NewPrivateOwnSymbol() {
+Handle<Symbol> Factory::NewPrivateOwnSymbol(Handle<Object> name) {
   Handle<Symbol> symbol = NewSymbol();
   symbol->set_is_private(true);
   symbol->set_is_own(true);
+  if (name->IsString()) {
+    symbol->set_name(*name);
+  } else {
+    DCHECK(name->IsUndefined());
+  }
   return symbol;
 }