Do not trigger new history entry if iframe URL doesn't change

Source/core/loader/FrameLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 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) 2008 Alp Toker <alp@atoker.com>
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 Kris Jordan <krisjordan@gmail.com>
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ skipping 745 matching lines @@
         if (action.policy() == NavigationPolicyDownload)
             m_client->loadURLExternally(action.resourceRequest(), NavigationPolicyDownload);
         else
             createWindowForRequest(request, *m_frame, action.policy(), request.shouldSendReferrer());
         return;
     }
 
     const KURL& url = request.resourceRequest().url();
     if (!action.shouldOpenInNewWindow() && shouldPerformFragmentNavigation(request.formState(), request.resourceRequest().httpMethod(), newLoadType, url)) {
         m_documentLoader->setTriggeringAction(action);
-        loadInSameDocument(url, nullptr, newLoadType == FrameLoadTypeStandard ? UpdateBackForwardList : DoNotUpdateBackForwardList, request.clientRedirect());
+        loadInSameDocument(url, nullptr, newLoadType == FrameLoadTypeStandard && !shouldTreatURLAsSameAsCurrent(url) ? UpdateBackForwardList : DoNotUpdateBackForwardList, request.clientRedirect());
         return;
     }
     bool sameURL = url == m_documentLoader->urlForHistory();
     loadWithNavigationAction(action, newLoadType, request.formState(), request.substituteData(), request.clientRedirect());
     // Example of this case are sites that reload the same URL with a different cookie
     // driving the generated content, or a master frame with links that drive a target
     // frame, where the user has clicked on the same link repeatedly.
     if (sameURL && newLoadType != FrameLoadTypeReload && newLoadType != FrameLoadTypeReloadFromOrigin && request.resourceRequest().httpMethod() != "POST")
         m_loadType = FrameLoadTypeSame;
 }
@@ skipping 617 matching lines @@
         return true;
     case XFrameOptionsInvalid:
         m_frame->document()->addConsoleMessageWithRequestIdentifier(JSMessageSource, ErrorMessageLevel, "Invalid 'X-Frame-Options' header encountered when loading '" + url.elidedString() + "': '" + content + "' is not a recognized directive. The header will be ignored.", requestIdentifier);
         return false;
     default:
         ASSERT_NOT_REACHED();
         return false;
     }
 }
 
+bool FrameLoader::shouldTreatURLAsSameAsCurrent(const KURL& url) const
+{
+    return m_currentItem && url == m_currentItem->url();
+}
+
 bool FrameLoader::shouldTreatURLAsSrcdocDocument(const KURL& url) const
 {
     if (!equalIgnoringCase(url.string(), "about:srcdoc"))
         return false;
     HTMLFrameOwnerElement* ownerElement = m_frame->ownerElement();
     if (!isHTMLIFrameElement(ownerElement))
         return false;
     return ownerElement->fastHasAttribute(srcdocAttr);
 }
 
@@ skipping 55 matching lines @@
 {
     SandboxFlags flags = m_forcedSandboxFlags;
     if (LocalFrame* parentFrame = m_frame->tree().parent())
         flags |= parentFrame->document()->sandboxFlags();
     if (HTMLFrameOwnerElement* ownerElement = m_frame->ownerElement())
         flags |= ownerElement->sandboxFlags();
     return flags;
 }
 
 } // namespace WebCore