This is an attempt to address the Webrat / Nokogiri compatibility issue
[discussed here]. It monkeypatches Webrat to explicitly add the old
default arguments to the invocation of to_xpath.

Move monkey patch to its own file under test/support/webrat.
I really need to get rid of webrat.

Closes #5475

[discussed here] https://github.com/sparklemotion/nokogiri/issues/2469