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

Source/core/loader/FrameLoader.cpp

Index: Source/core/loader/FrameLoader.cpp
diff --git a/Source/core/loader/FrameLoader.cpp b/Source/core/loader/FrameLoader.cpp
index 2f3d4e2b29a3d37a647706ce190c7b7291519575..1813ddbae644fa52076f5a026bc876095675b4d0 100644
--- a/Source/core/loader/FrameLoader.cpp
+++ b/Source/core/loader/FrameLoader.cpp
@@ -763,7 +763,7 @@ void FrameLoader::load(const FrameLoadRequest& passedRequest)
     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();
@@ -1401,6 +1401,11 @@ bool FrameLoader::shouldInterruptLoadForXFrameOptions(const String& content, con
     }
 }
 
+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"))