[promise] use PromiseCapabilities directly for Promise.race resolve/reject

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();
 
@@ skipping 376 matching lines @@
 }
 
 function PromiseRace(iterable) {
   if (!IS_RECEIVER(this)) {
     throw MakeTypeError(kCalledOnNonObject, PromiseRace);
   }
 
   var deferred = NewPromiseCapability(this);
   try {
     for (var value of iterable) {
-      var reject = reason => { deferred.reject(reason); };
-      this.resolve(value).then((x) => { deferred.resolve(x) }, reject);
-      SET_PRIVATE(reject, promiseCombinedDeferredSymbol, deferred);
+      this.resolve(value).then(deferred.resolve, deferred.reject);
+      SET_PRIVATE(deferred.reject, promiseCombinedDeferredSymbol, deferred);
     }
   } catch (e) {
     deferred.reject(e)
   }
   return deferred.promise;
 }
 
 
 // Utility for debugger
 
@@ skipping 65 matching lines @@
 [PromiseChain, PromiseDeferred, PromiseResolved].forEach(
     fn => %FunctionRemovePrototype(fn));
 
 utils.Export(function(to) {
   to.PromiseChain = PromiseChain;
   to.PromiseDeferred = PromiseDeferred;
   to.PromiseResolved = PromiseResolved;
 });
 
 })