[esnext] prototype runtime implementation for async functions

src/js/promise.js

Index: src/js/promise.js
diff --git a/src/js/promise.js b/src/js/promise.js
index bcf826a10151d48a498d40e72f418805a5022f18..719ecdc48fab72a03ed2d79293eb11a6917d64c1 100644
--- a/src/js/promise.js
+++ b/src/js/promise.js
@@ -268,6 +268,19 @@ function PromiseRejected(r) {
   }
 }
 
+// Shortcut Promise.reject and Promise.resolve() implementations, used by
+// Async Functions implementation.
+function PromiseCreateRejected(r) {
+  var promise = PromiseCreateAndSet(-1, r);
+  %PromiseRejectEvent(promise, r, false);
+  return promise;
+}
+
+function PromiseCreateResolved(x) {
+  if (IsPromise(x) && x.constructor === GlobalPromise) return x;
+  return PromiseCreateAndSet(+1, x);
+}
+
 // Multi-unwrapped chaining with thenable coercion.
 
 function PromiseThen(onResolve, onReject) {
@@ -451,6 +464,7 @@ utils.InstallFunctions(GlobalPromise.prototype, DONT_ENUM, [
   "promise_reject", PromiseReject,
   "promise_resolve", PromiseResolve,
   "promise_then", PromiseThen,
+  "promise_create_rejected", PromiseCreateRejected
 ]);
 
 // This allows extras to create promises quickly without building extra
@@ -470,6 +484,10 @@ utils.Export(function(to) {
   to.PromiseChain = PromiseChain;
   to.PromiseDeferred = PromiseDeferred;
   to.PromiseResolved = PromiseResolved;
+
+  to.PromiseCreateRejected = PromiseCreateRejected;
+  to.PromiseCreateResolved = PromiseCreateResolved;
+  to.PromiseThen = PromiseThen;
 });
 
 })