Revert of Fix Blink commit type for subframes after initial about:blank load.

Source/core/loader/NavigationScheduler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2009 Adam Barth. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
@@ skipping 274 matching lines @@
         schedule(ScheduledRedirect::create(delay, m_frame->document(), url, delay <= 1));
 }
 
 bool NavigationScheduler::mustLockBackForwardList(LocalFrame* targetFrame)
 {
     // Non-user navigation before the page has finished firing onload should not create a new back/forward item.
     // See https://webkit.org/b/42861 for the original motivation for this.
     if (!UserGestureIndicator::processingUserGesture() && !targetFrame->document()->loadEventFinished())
         return true;
 
+    // From the HTML5 spec for location.assign():
+    //  "If the browsing context's session history contains only one Document,
+    //   and that was the about:blank Document created when the browsing context
+    //   was created, then the navigation must be done with replacement enabled."
+    if (!targetFrame->loader().stateMachine()->committedMultipleRealLoads()
+        && equalIgnoringCase(targetFrame->document()->url(), blankURL()))
+        return true;
+
     // Navigation of a subframe during loading of an ancestor frame does not create a new back/forward item.
     // The definition of "during load" is any time before all handlers for the load event have been run.
     // See https://bugs.webkit.org/show_bug.cgi?id=14957 for the original motivation for this.
     Frame* parentFrame = targetFrame->tree().parent();
     return parentFrame && parentFrame->isLocalFrame() && !toLocalFrame(parentFrame)->loader().allAncestorsAreComplete();
 }
 
 void NavigationScheduler::scheduleLocationChange(Document* originDocument, const String& url, bool lockBackForwardList)
 {
     if (!shouldScheduleNavigation(url))
@@ skipping 103 matching lines @@
     m_redirect.clear();
 }
 
 DEFINE_TRACE(NavigationScheduler)
 {
     visitor->trace(m_frame);
     visitor->trace(m_redirect);
 }
 
 } // namespace blink