ES6: Add support for Map.prototype.forEach and Set.prototype.forEach

src/objects-visiting.cc

Index: src/objects-visiting.cc
diff --git a/src/objects-visiting.cc b/src/objects-visiting.cc
index b314a4788a9af7d647f47c92c8641996542b54f8..b70ee3f0f47ff397c75576c49a8fefc66c98b350 100644
--- a/src/objects-visiting.cc
+++ b/src/objects-visiting.cc
@@ -110,6 +110,12 @@ StaticVisitorBase::VisitorId StaticVisitorBase::GetVisitorId(
                                  kVisitStructGeneric,
                                  JSMap::kSize);
 
+    case JS_SET_ITERATOR_TYPE:
+      return kVisitJSSetIterator;
+
+    case JS_MAP_ITERATOR_TYPE:
+      return kVisitJSMapIterator;
+
     case JS_WEAK_MAP_TYPE:
       return kVisitJSWeakMap;