Native context: do not put public symbols and flags on the js builtins object.

src/promise.js

 // Copyright 2012 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.
 
 (function(global, utils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
 // -------------------------------------------------------------------
 // Imports
 
 var InternalArray = utils.InternalArray;
 var promiseHasHandlerSymbol =
-    utils.GetPrivateSymbol("promise_has_handler_symbol");
-var promiseOnRejectSymbol = utils.GetPrivateSymbol("promise_on_reject_symbol");
+    utils.ImportNow("promise_has_handler_symbol");
+var promiseOnRejectSymbol = utils.ImportNow("promise_on_reject_symbol");
 var promiseOnResolveSymbol =
-    utils.GetPrivateSymbol("promise_on_resolve_symbol");
-var promiseRawSymbol = utils.GetPrivateSymbol("promise_raw_symbol");
-var promiseStatusSymbol = utils.GetPrivateSymbol("promise_status_symbol");
-var promiseValueSymbol = utils.GetPrivateSymbol("promise_value_symbol");
+    utils.ImportNow("promise_on_resolve_symbol");
+var promiseRawSymbol = utils.ImportNow("promise_raw_symbol");
+var promiseStatusSymbol = utils.ImportNow("promise_status_symbol");
+var promiseValueSymbol = utils.ImportNow("promise_value_symbol");
+var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
 
 // -------------------------------------------------------------------
 
 // Status values: 0 = pending, +1 = resolved, -1 = rejected
 var lastMicrotaskId = 0;
 
 var GlobalPromise = function Promise(resolver) {
   if (resolver === promiseRawSymbol) return;
   if (!%_IsConstructCall()) throw MakeTypeError(kNotAPromise, this);
   if (!IS_SPEC_FUNCTION(resolver))
@@ skipping 321 matching lines @@
 // handler somewhere down the promise chain. For this, we do a depth-first
 // search for a reject handler that's not the default PromiseIdRejectHandler.
 function PromiseHasUserDefinedRejectHandler() {
   return PromiseHasUserDefinedRejectHandlerRecursive(this);
 };
 
 // -------------------------------------------------------------------
 // Install exported functions.
 
 %AddNamedProperty(global, 'Promise', GlobalPromise, DONT_ENUM);
-%AddNamedProperty(GlobalPromise.prototype, symbolToStringTag, "Promise",
+%AddNamedProperty(GlobalPromise.prototype, toStringTagSymbol, "Promise",
                   DONT_ENUM | READ_ONLY);
 
 utils.InstallFunctions(GlobalPromise, DONT_ENUM, [
   "defer", PromiseDeferred,
   "accept", PromiseResolved,
   "reject", PromiseRejected,
   "all", PromiseAll,
   "race", PromiseRace,
   "resolve", PromiseCast
 ]);
 
 utils.InstallFunctions(GlobalPromise.prototype, DONT_ENUM, [
   "chain", PromiseChain,
   "then", PromiseThen,
   "catch", PromiseCatch
 ]);
 
 %InstallToContext([
   "promise_catch", PromiseCatch,
   "promise_chain", PromiseChain,
   "promise_create", PromiseCreate,
   "promise_has_user_defined_reject_handler", PromiseHasUserDefinedRejectHandler,
   "promise_reject", PromiseReject,
   "promise_resolve", PromiseResolve,
   "promise_then", PromiseThen,
 ]);
 
 })