Desugar async/await to create the resulting Promise upfront

src/js/promise.js

Index: src/js/promise.js
diff --git a/src/js/promise.js b/src/js/promise.js
index a666080e78654b0474a48badc009058a416ab39c..a1e871ea50e5c678e0ef0e0369720c219fa1e116 100644
--- a/src/js/promise.js
+++ b/src/js/promise.js
@@ -305,14 +305,14 @@ function ResolvePromise(promise, resolution) {
 
 // ES#sec-rejectpromise
 // RejectPromise ( promise, reason )
-function RejectPromise(promise, reason) {
+function RejectPromise(promise, reason, skipEvent) {
   // Check promise status to confirm that this reject has an effect.
   // Call runtime for callbacks to the debugger or for unhandled reject.
   if (GET_PRIVATE(promise, promiseStateSymbol) === kPending) {
     var debug_is_active = DEBUG_IS_ACTIVE;
     if (debug_is_active ||
         !HAS_DEFINED_PRIVATE(promise, promiseHasHandlerSymbol)) {
-      %PromiseRejectEvent(promise, reason, debug_is_active);
+      %PromiseRejectEvent(promise, reason, debug_is_active && !skipEvent);
     }
   }
   FulfillPromise(promise, kRejected, reason, promiseRejectReactionsSymbol)
@@ -378,18 +378,6 @@ function PromiseReject(r) {
   }
 }
 
-// Shortcut Promise.reject and Promise.resolve() implementations, used by
-// Async Functions implementation.
-function PromiseCreateRejected(r) {
-  return %_Call(PromiseReject, GlobalPromise, r);
-}
-
-function PromiseCreateResolved(value) {
-  var promise = PromiseInit(new GlobalPromise(promiseRawSymbol));
-  var resolveResult = ResolvePromise(promise, value);
-  return promise;
-}
-
 function PromiseCastResolved(value) {
   if (IsPromise(value)) {
     return value;
@@ -621,8 +609,6 @@ utils.InstallFunctions(GlobalPromise.prototype, DONT_ENUM, [
   "promise_reject", RejectPromise,
   "promise_resolve", ResolvePromise,
   "promise_then", PromiseThen,
-  "promise_create_rejected", PromiseCreateRejected,
-  "promise_create_resolved", PromiseCreateResolved
 ]);
 
 // This allows extras to create promises quickly without building extra