[esnext] prototype runtime implementation for async functions

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 275 matching lines @@
     // which is usually simply noise. Do not trigger that debug event.
     %PromiseRejectEvent(promise, r, false);
     return promise;
   } else {
     var promiseCapability = NewPromiseCapability(this);
     %_Call(promiseCapability.reject, UNDEFINED, r);
     return promiseCapability.promise;
   }
 }
 
+// Shortcut Promise.reject and Promise.resolve() implementations, used by
+// Async Functions implementation.
+function PromiseCreateRejected(r) {
+  return %_Call(PromiseReject, GlobalPromise, r);
+}
+
+function PromiseCreateResolved(x) {
+  return %_Call(PromiseResolve, GlobalPromise, x);
+}
+
 // ES#sec-promise.prototype.then
 // Promise.prototype.then ( onFulfilled, onRejected )
 // Multi-unwrapped chaining with thenable coercion.
 function PromiseThen(onResolve, onReject) {
   var status = GET_PRIVATE(this, promiseStateSymbol);
   if (IS_UNDEFINED(status)) {
     throw MakeTypeError(kNotAPromise, this);
   }
 
   var constructor = SpeciesConstructor(this, GlobalPromise);
@@ skipping 174 matching lines @@
 ]);
 
 %InstallToContext([
   "promise_catch", PromiseCatch,
   "promise_chain", PromiseChain,
   "promise_create", PromiseCreate,
   "promise_has_user_defined_reject_handler", PromiseHasUserDefinedRejectHandler,
   "promise_reject", RejectPromise,
   "promise_resolve", FulfillPromise,
   "promise_then", PromiseThen,
+  "promise_create_rejected", PromiseCreateRejected,
+  "promise_create_resolved", PromiseCreateResolved
 ]);
 
 // This allows extras to create promises quickly without building extra
 // 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,
   "resolvePromise", FulfillPromise,
   "rejectPromise", RejectPromise
 ]);
 
 // TODO(v8:4567): Allow experimental natives to remove function prototype
 [PromiseChain, PromiseDefer, PromiseAccept].forEach(
     fn => %FunctionRemovePrototype(fn));
 
 utils.Export(function(to) {
   to.PromiseChain = PromiseChain;
   to.PromiseDefer = PromiseDefer;
   to.PromiseAccept = PromiseAccept;
+
+  to.PromiseCreateRejected = PromiseCreateRejected;
+  to.PromiseCreateResolved = PromiseCreateResolved;
+  to.PromiseThen = PromiseThen;
 });
 
 })