Do not fire didStartLoading and didStopLoading events twice.

Source/core/dom/Document.h

 /*
  * 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, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 893 matching lines @@
         BeforeUnloadEventCompleted,
         PageHideInProgress,
         UnloadEventInProgress,
         UnloadEventHandled
     };
     bool loadEventStillNeeded() const { return m_loadEventProgress == LoadEventNotRun; }
     bool processingLoadEvent() const { return m_loadEventProgress == LoadEventInProgress; }
     bool loadEventFinished() const { return m_loadEventProgress >= LoadEventCompleted; }
     bool unloadStarted() const { return m_loadEventProgress >= PageHideInProgress; }
     bool processingBeforeUnload() const { return m_loadEventProgress == BeforeUnloadEventInProgress; }
+    bool shouldFireLoadingEvents() const { return m_loadEventProgress == LoadEventCompleted; }

[Nate Chapin, 2015/03/06 18:22:20]

This name seems overly specific to its usage. isNotLoadingOrUnloading?
completeButNotUnloading? inStableLoadingState?

[Fabrice (no longer in Chrome), 2015/03/06 18:39:13]

I kinda like it because it's only really supposed to be used for that.
Anyway, I changed it to isLoadEventCompleted.

     void suppressLoadEvent();
 
     void setContainsPlugins() { m_containsPlugins = true; }
     bool containsPlugins() const { return m_containsPlugins; }
 
     virtual bool isContextThread() const override final;
     virtual bool isJSExecutionForbidden() const override final { return false; }
 
     bool containsValidityStyleRules() const { return m_containsValidityStyleRules; }
     void setContainsValidityStyleRules() { m_containsValidityStyleRules = true; }
@@ skipping 507 matching lines @@
 DEFINE_TYPE_CASTS(TreeScope, Document, document, true, true);
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLiveDocumentInstances();
 #endif
 
 #endif // Document_h