[runtime] We don't need an actual instance type for JSIteratorResult.

src/factory.cc

Index: src/factory.cc
diff --git a/src/factory.cc b/src/factory.cc
index 3d094c9cb25fd5ffaf7f18c1fa3f22b6e607dcc1..fc40fe6c2dd1cdbf9d3f1299793d53518737afd2 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -1737,16 +1737,6 @@ Handle<JSSetIterator> Factory::NewJSSetIterator() {
 }
 
 
-Handle<JSIteratorResult> Factory::NewJSIteratorResult(Handle<Object> value,
-                                                      Handle<Object> done) {
-  Handle<JSIteratorResult> result = Handle<JSIteratorResult>::cast(
-      NewJSObjectFromMap(isolate()->iterator_result_map()));
-  result->set_value(*value);
-  result->set_done(*done);
-  return result;
-}
-
-
 namespace {
 
 ElementsKind GetExternalArrayElementsKind(ExternalArrayType type) {