Don't reuse HistoryItems for multiple navigations

Source/core/loader/FrameLoader.h

Index: Source/core/loader/FrameLoader.h
diff --git a/Source/core/loader/FrameLoader.h b/Source/core/loader/FrameLoader.h
index 9f575075104c3be4628e253ee493d08b2328ef5f..3bf958ac3c9b9432fec255e12a160d7b292a6734 100644
--- a/Source/core/loader/FrameLoader.h
+++ b/Source/core/loader/FrameLoader.h
@@ -171,7 +171,6 @@ public:
 
     HistoryItem* currentItem() const { return m_currentItem.get(); }
     void saveScrollState();
-    void clearScrollPositionAndViewState();
 
     void restoreScrollPositionAndViewState();
 
@@ -192,8 +191,12 @@ private:
 
     void startLoad(FrameLoadRequest&, FrameLoadType, NavigationPolicy);
 
-
-    void setHistoryItemStateForCommit(HistoryCommitType, bool isPushOrReplaceState = false, HistoryScrollRestorationType = ScrollRestorationAuto, PassRefPtr<SerializedScriptValue> = nullptr);
+    enum class HistoryNavigationType {
+        DifferentDocument,
+        Fragment,
+        HistoryApi
+    };
+    void setHistoryItemStateForCommit(HistoryCommitType, HistoryNavigationType);
 
     void loadInSameDocument(const KURL&, PassRefPtr<SerializedScriptValue> stateObject, FrameLoadType, ClientRedirectPolicy);