Re^3-land "Ship promises and weak collections"

src/promise.js

Index: src/promise.js
diff --git a/src/promise.js b/src/promise.js
index f638f63d26027d24ef11d6d406b87b5098806b3a..fa650eaf0e983d31d988dc7093d11398ea515091 100644
--- a/src/promise.js
+++ b/src/promise.js
@@ -10,7 +10,22 @@
 // var $WeakMap = global.WeakMap
 
 
-var $Promise = Promise;
+var $Promise = function Promise(resolver) {
+  if (resolver === promiseRaw) return;
+  if (!%_IsConstructCall()) throw MakeTypeError('not_a_promise', [this]);
+  if (!IS_SPEC_FUNCTION(resolver))
+    throw MakeTypeError('resolver_not_a_function', [resolver]);
+  var promise = PromiseInit(this);
+  try {
+    %DebugPromiseHandlePrologue(function() { return promise });
+    resolver(function(x) { PromiseResolve(promise, x) },
+             function(r) { PromiseReject(promise, r) });
+  } catch (e) {
+    PromiseReject(promise, e);
+  } finally {
+    %DebugPromiseHandleEpilogue();
+  }
+}
 
 
 //-------------------------------------------------------------------
@@ -28,23 +43,6 @@ function IsPromise(x) {
   return IS_SPEC_OBJECT(x) && %HasLocalProperty(x, promiseStatus);
 }
 
-function Promise(resolver) {
-  if (resolver === promiseRaw) return;
-  if (!%_IsConstructCall()) throw MakeTypeError('not_a_promise', [this]);
-  if (typeof resolver !== 'function')
-    throw MakeTypeError('resolver_not_a_function', [resolver]);
-  var promise = PromiseInit(this);
-  try {
-    %DebugPromiseHandlePrologue(function() { return promise });
-    resolver(function(x) { PromiseResolve(promise, x) },
-             function(r) { PromiseReject(promise, r) });
-  } catch (e) {
-    PromiseReject(promise, e);
-  } finally {
-    %DebugPromiseHandleEpilogue();
-  }
-}
-
 function PromiseSet(promise, status, value, onResolve, onReject) {
   SET_PRIVATE(promise, promiseStatus, status);
   SET_PRIVATE(promise, promiseValue, value);
@@ -78,7 +76,7 @@ function PromiseReject(promise, r) {
 function PromiseNopResolver() {}
 
 function PromiseCreate() {
-  return new Promise(PromiseNopResolver)
+  return new $Promise(PromiseNopResolver)
 }
 
 
@@ -87,7 +85,7 @@ function PromiseCreate() {
 function PromiseDeferred() {
   if (this === $Promise) {
     // Optimized case, avoid extra closure.
-    var promise = PromiseInit(new Promise(promiseRaw));
+    var promise = PromiseInit(new $Promise(promiseRaw));
     return {
       promise: promise,
       resolve: function(x) { PromiseResolve(promise, x) },
@@ -106,7 +104,7 @@ function PromiseDeferred() {
 function PromiseResolved(x) {
   if (this === $Promise) {
     // Optimized case, avoid extra closure.
-    return PromiseSet(new Promise(promiseRaw), +1, x);
+    return PromiseSet(new $Promise(promiseRaw), +1, x);
   } else {
     return new this(function(resolve, reject) { resolve(x) });
   }
@@ -115,7 +113,7 @@ function PromiseResolved(x) {
 function PromiseRejected(r) {
   if (this === $Promise) {
     // Optimized case, avoid extra closure.
-    return PromiseSet(new Promise(promiseRaw), -1, r);
+    return PromiseSet(new $Promise(promiseRaw), -1, r);
   } else {
     return new this(function(resolve, reject) { reject(r) });
   }
@@ -190,10 +188,8 @@ function PromiseHandle(value, handler, deferred) {
 // Multi-unwrapped chaining with thenable coercion.
 
 function PromiseThen(onResolve, onReject) {
-  onResolve =
-    IS_NULL_OR_UNDEFINED(onResolve) ? PromiseIdResolveHandler : onResolve;
-  onReject =
-    IS_NULL_OR_UNDEFINED(onReject) ? PromiseIdRejectHandler : onReject;
+  onResolve = IS_SPEC_FUNCTION(onResolve) ? onResolve : PromiseIdResolveHandler;
+  onReject = IS_SPEC_FUNCTION(onReject) ? onReject : PromiseIdRejectHandler;
   var that = this;
   var constructor = this.constructor;
   return %_CallFunction(