[es6] Introduce a dedicated JSIteratorResult type.

src/runtime/runtime-object.cc

Index: src/runtime/runtime-object.cc
diff --git a/src/runtime/runtime-object.cc b/src/runtime/runtime-object.cc
index e53aef688ab63fcfd12dafd14bfa829313c799cf..5945488831e9a705881845f988db47d91e5f9753 100644
--- a/src/runtime/runtime-object.cc
+++ b/src/runtime/runtime-object.cc
@@ -1558,5 +1558,15 @@ RUNTIME_FUNCTION(Runtime_HasInPrototypeChain) {
       object->HasInPrototypeChain(isolate, prototype));
 }
 
+
+// ES6 section 7.4.7 CreateIterResultObject ( value, done )
+RUNTIME_FUNCTION(Runtime_CreateIterResultObject) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(2, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(Object, value, 0);
+  CONVERT_ARG_HANDLE_CHECKED(Object, done, 1);
+  return *isolate->factory()->NewJSIteratorResult(value, done);
+}
+
 }  // namespace internal
 }  // namespace v8