New feature : extensions functions in Xpath (not only xslt)

Hi,

Since extension-element-prefixes="..." is not needed in the stylesheet
root element for using xpath extensions functions in a xslt, it should
be a very nice feature to make available extensions functions in Xpath
compiler too.

Simple example that should work :

var vResolver = {
  lookupNamespaceURI : function(pPrefix) {
    if(pPrefix=="regexp") return "http://exslt.org/regular-
expressions";
    return null;
  }
}
var vXpath = document.createExpression("regexp:replace('test', 't',
'g', 'X')", vResolver);


What do you think ?