For AND operator, the left operand should have parentheses, not only right

Created by: achasseux

Hello,

When CSS selector is translated into XPath, the following

e[foo!="bar"][foo!="baz"]

becomes :

e[not(@foo) or @foo != 'bar' and (not(@foo) or @foo != 'baz')]

It should become :

e[(not(@foo) or @foo != 'bar') and (not(@foo) or @foo != 'baz')]

This pull request adds the left-operand parentheses.