Split the frame tree logic out of HistoryItem

Source/core/history/HistoryItem.h

Index: Source/core/history/HistoryItem.h
diff --git a/Source/core/history/HistoryItem.h b/Source/core/history/HistoryItem.h
index 4bd3524f44a6daf47b4bbe4a952555f422ed4d5b..68e34f97cc4f1d18d813cb6867e9f700b41a22d4 100644
--- a/Source/core/history/HistoryItem.h
+++ b/Source/core/history/HistoryItem.h
@@ -99,28 +99,15 @@ public:
     void setFormContentType(const String&);
 
     void addChildItem(PassRefPtr<HistoryItem>);
-    void setChildItem(PassRefPtr<HistoryItem>);
-    HistoryItem* childItemWithTarget(const String&) const;
-    HistoryItem* childItemWithDocumentSequenceNumber(long long number) const;
     const HistoryItemVector& children() const;
     void clearChildren();
 
-    bool shouldDoSameDocumentNavigationTo(HistoryItem* otherItem) const;
-    bool hasSameFrames(HistoryItem* otherItem) const;
-
     bool isCurrentDocument(Document*) const;
 
-#ifndef NDEBUG
-    int showTree() const;
-    int showTreeWithIndent(unsigned indentLevel) const;
-#endif
-
 private:
     HistoryItem();
     explicit HistoryItem(const HistoryItem&);
 
-    bool hasSameDocumentTree(HistoryItem* otherItem) const;
-
     String m_urlString;
     String m_originalURLString;
     String m_referrer;
@@ -156,9 +143,4 @@ private:
 
 } //namespace WebCore
 
-#ifndef NDEBUG
-// Outside the WebCore namespace for ease of invocation from gdb.
-extern "C" int showTree(const WebCore::HistoryItem*);
-#endif
-
 #endif // HISTORYITEM_H