Fix bad cast to XPath::Filter in XPathGrammar.y

Source/core/xml/XPathPath.cpp

 /*
  * Copyright (C) 2005 Frerich Raabe <raabe@kde.org>
  * Copyright (C) 2006, 2009 Apple Inc.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 167 matching lines @@
         if (dropSecondStep) {
             delete m_steps[0];
             m_steps[0] = step;
             return;
         }
     }
     step->optimize();
     m_steps.insert(0, step);
 }
 
-Path::Path(Filter* filter, LocationPath* path)
+Path::Path(Expression* filter, LocationPath* path)
     : m_filter(filter)
     , m_path(path)
 {
     setIsContextNodeSensitive(filter->isContextNodeSensitive());
     setIsContextPositionSensitive(filter->isContextPositionSensitive());
     setIsContextSizeSensitive(filter->isContextSizeSensitive());
 }
 
 Path::~Path()
 {
     delete m_filter;
     delete m_path;
 }
 
 Value Path::evaluate() const
 {
     Value v = m_filter->evaluate();
 
     NodeSet& nodes = v.modifiableNodeSet();
     m_path->evaluate(nodes);
 
     return v;
 }
 
 }
 }