Debugger: allow stepping into resolver from Promise constructor.

src/js/collection.js

Index: src/js/collection.js
diff --git a/src/js/collection.js b/src/js/collection.js
index 8bf6ec3515baf2c2ebd2b4ead4c300671ea8064e..b6176bbd2eccca2e40a1f875c2033fd82078b320 100644
--- a/src/js/collection.js
+++ b/src/js/collection.js
@@ -249,7 +249,7 @@ function SetForEach(f, receiver) {
 
   var iterator = new SetIterator(this, ITERATOR_KIND_VALUES);
   var key;
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING(f);
   var value_array = [UNDEFINED];
   while (%SetIteratorNext(iterator, value_array)) {
     if (stepping) %DebugPrepareStepInIfStepping(f);
@@ -432,7 +432,7 @@ function MapForEach(f, receiver) {
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
 
   var iterator = new MapIterator(this, ITERATOR_KIND_ENTRIES);
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING(f);
   var value_array = [UNDEFINED, UNDEFINED];
   while (%MapIteratorNext(iterator, value_array)) {
     if (stepping) %DebugPrepareStepInIfStepping(f);