I have recently been working with XPath and have been searching for information on which browsers support XPath 2.0 without much luck. The best I could find was the query te
Majority of the browsers do not support XPATH 2.0, please see Comparison of layout engines to get more information.
However you may get support of the XPATH 2.0 in Firefox by using Saxon-CE, see more on the MDN XSLT_2.0 page.