Currently, GC related code is scattered over V8Binding, V8Proxy, ScriptGCEvent etc. We can rename ScriptGCEvent.{h,cpp} to V8GCObserver.{h,cpp}. In a follow-up patch, I'll move GC related code to V8GCObserver.{h,cpp}.
I found that ScriptGCEvent.{h,cpp} exists not only in V8 but also in JSC. After some investigation, it seems to me that we don't want to rename it.