PromiseThen should ignore non-function parameters.

src/promise.js

Index: src/promise.js
diff --git a/src/promise.js b/src/promise.js
index 82aa99027a1305ac8bf6b95672cccd89504173cd..b3bae9efd7e4fe656bc1e5ea47d62f1bead1f9d4 100644
--- a/src/promise.js
+++ b/src/promise.js
@@ -148,8 +148,9 @@ function PromiseIdResolveHandler(x) { return x }
 function PromiseIdRejectHandler(r) { throw r }
 
 function PromiseChain(onResolve, onReject) {  // a.k.a.  flatMap
-  onResolve = IS_UNDEFINED(onResolve) ? PromiseIdResolveHandler : onResolve;
-  onReject = IS_UNDEFINED(onReject) ? PromiseIdRejectHandler : onReject;
+  onResolve =
+    typeof onResolve === 'function' ? onResolve : PromiseIdResolveHandler;

[rossberg, 2014/04/28 08:32:52]

We shouldn't change .chain, only .then

[yhirano, 2014/04/28 12:35:40]

Done.

+  onReject = typeof onReject === 'function' ? onReject : PromiseIdRejectHandler;
   var deferred = %_CallFunction(this.constructor, PromiseDeferred);
   switch (GET_PRIVATE(this, promiseStatus)) {
     case UNDEFINED:
@@ -201,7 +202,8 @@ function PromiseHandle(value, handler, deferred) {
 // Multi-unwrapped chaining with thenable coercion.
 
 function PromiseThen(onResolve, onReject) {
-  onResolve = IS_UNDEFINED(onResolve) ? PromiseIdResolveHandler : onResolve;
+  onResolve =
+    typeof onResolve === 'function' ? onResolve : PromiseIdResolveHandler;

[rossberg, 2014/04/28 08:32:52]

Please use the IS_SPEC_FUNCTION macro instead.

[yhirano, 2014/04/28 12:35:40]

Done.

   var that = this;
   var constructor = this.constructor;
   return this.chain(