[promise] make Promise.resolve match spec

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 336 matching lines @@
         return onResolve(x);
       }
     },
     onReject
   );
 }
 
 // Combinators.
 
 function PromiseCast(x) {
-  if (IsPromise(x) && x.constructor === this) {
-    return x;
-  } else {
-    return new this(function(resolve) { resolve(x) });
+  if (!IS_RECEIVER(this)) {
+    throw MakeTypeError(kCalledOnNonObject, "Promise.resolve");
   }
+
+  if (IsPromise(x) && x.constructor === this) return x;
+
+  var promiseCapability = NewPromiseCapability(this);

[caitp (gmail), 2016/01/04 14:52:11]

Technically, the assertions added in NewPromiseCapability in a separate CL are
important here, and observable in test262 tests fixed in that other CL --- so I
don't think we can take the shortcut as done in the deleted code :(

[Dan Ehrenberg, 2016/01/04 18:04:20]

Yep, I agree. Still looks good to me. The trybot just failed because it needs a
rebase.

+  var resolveResult = promiseCapability.resolve(x);
+  return promiseCapability.promise;
 }
 
 function PromiseAll(iterable) {
   var deferred = NewPromiseCapability(this);
   var resolutions = [];
   try {
     var count = 0;
     var i = 0;
     for (var value of iterable) {
       var reject = function(r) { deferred.reject(r) };
@@ skipping 106 matching lines @@
 [PromiseChain, PromiseDeferred, PromiseResolved].forEach(
     fn => %FunctionRemovePrototype(fn));
 
 utils.Export(function(to) {
   to.PromiseChain = PromiseChain;
   to.PromiseDeferred = PromiseDeferred;
   to.PromiseResolved = PromiseResolved;
 });
 
 })