All private symbols are own symbols

src/factory.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_FACTORY_H_
 #define V8_FACTORY_H_
 
 #include "src/isolate.h"
 #include "src/messages.h"
 
@@ skipping 207 matching lines @@
   // not make sense to have a UTF-8 factory function for external strings,
   // because we cannot change the underlying buffer.  Note that these strings
   // are backed by a string resource that resides outside the V8 heap.
   MUST_USE_RESULT MaybeHandle<String> NewExternalStringFromOneByte(
       const ExternalOneByteString::Resource* resource);
   MUST_USE_RESULT MaybeHandle<String> NewExternalStringFromTwoByte(
       const ExternalTwoByteString::Resource* resource);
 
   // Create a symbol.
   Handle<Symbol> NewSymbol();
-  Handle<Symbol> NewPrivateSymbol();
-  Handle<Symbol> NewPrivateOwnSymbol(Handle<Object> name);
+  Handle<Symbol> NewPrivateSymbol(Handle<Object> name);
 
   // Create a global (but otherwise uninitialized) context.
   Handle<Context> NewNativeContext();
 
   // Create a script context.
   Handle<Context> NewScriptContext(Handle<JSFunction> function,
                                    Handle<ScopeInfo> scope_info);
 
   // Create an empty script context table.
   Handle<ScriptContextTable> NewScriptContextTable();
@@ skipping 498 matching lines @@
   // Reinitialize a JSProxy into an (empty) JS object of respective type and
   // size, but keeping the original prototype.  The receiver must have at least
   // the size of the new object.  The object is reinitialized and behaves as an
   // object that has been freshly allocated.
   void ReinitializeJSProxy(Handle<JSProxy> proxy, InstanceType type, int size);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_FACTORY_H_