Add Object::IsNullOrUndefined(Isolate*) helper method

src/string-stream.cc

Index: src/string-stream.cc
diff --git a/src/string-stream.cc b/src/string-stream.cc
index 0d1e70d9a90756206b18cde39ccd08a92ffff6cb..07f26a01495881d9ae69b4cca464c18f6063027e 100644
--- a/src/string-stream.cc
+++ b/src/string-stream.cc
@@ -481,8 +481,8 @@ void StringStream::PrintPrototype(JSFunction* fun, Object* receiver) {
   Object* name = fun->shared()->name();
   bool print_name = false;
   Isolate* isolate = fun->GetIsolate();
-  if (receiver->IsNull(isolate) || receiver->IsUndefined(isolate) ||
-      receiver->IsTheHole(isolate) || receiver->IsJSProxy()) {
+  if (receiver->IsNullOrUndefined(isolate) || receiver->IsTheHole(isolate) ||
+      receiver->IsJSProxy()) {
     print_name = true;
   } else if (isolate->context() != nullptr) {
     if (!receiver->IsJSObject()) {