Revert of Followup comments from r460581.

third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 1422 matching lines @@
 
   for (auto& it : event_listener_observers_) {
     it->DidAddEventListener(this, event_type);
   }
 
   if (event_type == EventTypeNames::unload) {
     UseCounter::Count(document(), UseCounter::kDocumentUnloadRegistered);
     AddUnloadEventListener(this);
   } else if (event_type == EventTypeNames::beforeunload) {
     UseCounter::Count(document(), UseCounter::kDocumentBeforeUnloadRegistered);
-    // This is confusingly named. It doesn't actually add the listener. It
-    // just increments a count so that we know we have listeners registered
-    // for the purposes of determining if we can fast terminate the renderer
-    // process.
     AddBeforeUnloadEventListener(this);
     if (GetFrame() && !GetFrame()->IsMainFrame())
       UseCounter::Count(document(),
                         UseCounter::kSubFrameBeforeUnloadRegistered);
   }
 }
 
 void LocalDOMWindow::RemovedEventListener(
     const AtomicString& event_type,
     const RegisteredEventListener& registered_listener) {
@@ skipping 210 matching lines @@
   DOMWindow::Trace(visitor);
   Supplementable<LocalDOMWindow>::Trace(visitor);
 }
 
 DEFINE_TRACE_WRAPPERS(LocalDOMWindow) {
   visitor->TraceWrappers(custom_elements_);
   DOMWindow::TraceWrappers(visitor);
 }
 
 }  // namespace blink