[promises] Remove unused symbols

src/js/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, extrasUtils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
 // -------------------------------------------------------------------
 // Imports
 
 var InternalArray = utils.InternalArray;
 var promiseAsyncStackIDSymbol =
     utils.ImportNow("promise_async_stack_id_symbol");
 var promiseHandledBySymbol =
     utils.ImportNow("promise_handled_by_symbol");
 var promiseForwardingHandlerSymbol =
     utils.ImportNow("promise_forwarding_handler_symbol");
 var promiseHandledHintSymbol =
     utils.ImportNow("promise_handled_hint_symbol");
-var promiseRawSymbol = utils.ImportNow("promise_raw_symbol");
-var promiseStateSymbol = utils.ImportNow("promise_state_symbol");
-var promiseResultSymbol = utils.ImportNow("promise_result_symbol");
-var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
-var ObjectHasOwnProperty;
+var ObjectHasOwnProperty; // Used by HAS_PRIVATE.
 var GlobalPromise = global.Promise;
-var PromiseThen = GlobalPromise.prototype.then;
 
 utils.Import(function(from) {
   ObjectHasOwnProperty = from.ObjectHasOwnProperty;
 });
 
 // -------------------------------------------------------------------
 
 // Core functionality.
 
 function PromiseDebugGetInfo(deferreds, status) {
@@ skipping 330 matching lines @@
 // resolve/reject closures, and allows them to later resolve and reject any
 // promise without having to hold on to those closures forever.
 utils.InstallFunctions(extrasUtils, 0, [
   "createPromise", PromiseCreate,
   "rejectPromise", DoRejectPromise,
   "markPromiseAsHandled", MarkPromiseAsHandled
 ]);
 
 utils.Export(function(to) {
   to.PromiseCreate = PromiseCreate;
-  to.PromiseThen = PromiseThen;
 
   to.CreateInternalPromiseCapability = CreateInternalPromiseCapability;
   to.RejectPromise = RejectPromise;
 });
 
 })