Remove visibilityChangeOnUnload runtime flag (as it's shipped)

third_party/WebKit/Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 3226 matching lines @@
     if (load_event_progress_ < kPageHideInProgress) {
       load_event_progress_ = kPageHideInProgress;
       if (LocalDOMWindow* window = domWindow())
         window->DispatchEvent(
             PageTransitionEvent::Create(EventTypeNames::pagehide, false), this);
       if (!frame_)
         return;
 
       PageVisibilityState visibility_state = GetPageVisibilityState();
       load_event_progress_ = kUnloadVisibilityChangeInProgress;
-      if (visibility_state != kPageVisibilityStateHidden &&
-          RuntimeEnabledFeatures::visibilityChangeOnUnloadEnabled()) {
+      if (visibility_state != kPageVisibilityStateHidden) {
         // Dispatch visibilitychange event, but don't bother doing
         // other notifications as we're about to be unloaded.
         DispatchEvent(Event::CreateBubble(EventTypeNames::visibilitychange));
         DispatchEvent(
             Event::CreateBubble(EventTypeNames::webkitvisibilitychange));
       }
       if (!frame_)
         return;
 
       DocumentLoader* document_loader =
@@ skipping 3555 matching lines @@
 }
 
 void showLiveDocumentInstances() {
   WeakDocumentSet& set = liveDocumentSet();
   fprintf(stderr, "There are %u documents currently alive:\n", set.size());
   for (blink::Document* document : set)
     fprintf(stderr, "- Document %p URL: %s\n", document,
             document->Url().GetString().Utf8().data());
 }
 #endif