Add Object::IsNullOrUndefined(Isolate*) helper method

src/debug/debug.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/debug/debug.h"
 
 #include <memory>
 
 #include "src/api.h"
 #include "src/arguments.h"
@@ skipping 2027 matching lines @@
                              Handle<Object> data) {
   GlobalHandles* global_handles = isolate_->global_handles();
 
   // Remove existing entry.
   GlobalHandles::Destroy(event_listener_.location());
   event_listener_ = Handle<Object>();
   GlobalHandles::Destroy(event_listener_data_.location());
   event_listener_data_ = Handle<Object>();
 
   // Set new entry.
-  if (!callback->IsUndefined(isolate_) && !callback->IsNull(isolate_)) {
+  if (!callback->IsNullOrUndefined(isolate_)) {
     event_listener_ = global_handles->Create(*callback);
     if (data.is_null()) data = isolate_->factory()->undefined_value();
     event_listener_data_ = global_handles->Create(*data);
   }
 
   UpdateState();
 }
 
 void Debug::SetMessageHandler(v8::Debug::MessageHandler handler) {
   message_handler_ = handler;
@@ skipping 437 matching lines @@
   logger_->DebugEvent("Put", message.text());
 }
 
 void LockingCommandMessageQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
   queue_.Clear();
 }
 
 }  // namespace internal
 }  // namespace v8