Remove some dead code from AXObjectCache

Source/core/accessibility/AXObjectCache.h

Index: Source/core/accessibility/AXObjectCache.h
diff --git a/Source/core/accessibility/AXObjectCache.h b/Source/core/accessibility/AXObjectCache.h
index c979344e3ed7b67d731dcf928165efb77f69086a..b91ac626d853d7a8822a1d870cbd74faf343fd47 100644
--- a/Source/core/accessibility/AXObjectCache.h
+++ b/Source/core/accessibility/AXObjectCache.h
@@ -158,10 +158,6 @@ public:
     AXID platformGenerateAXID() const;
     AXObject* objectFromAXID(AXID id) const { return m_objects.get(id); }
 
-    // Text marker utilities.
-    void textMarkerDataForVisiblePosition(TextMarkerData&, const VisiblePosition&);
-    VisiblePosition visiblePositionForTextMarkerData(TextMarkerData&);
-
     enum AXNotification {
         AXActiveDescendantChanged,
         AXAlert,