Test that XRegExp should not put (?:) at beginning/end of groups
Test that XRegExp should not put (?:) at beginning/end of groups

This test currently fails. Here's the actual and expected patterns, with
whitespace inserted to illustrate the difference:

'((?:)[0-9]{4}(?:))(?:)-?(?:)((?:)[0-9]{2}(?:))(?:)-?(?:)((?:)[0-9]{2}(?:))(?:)'
'(    [0-9]{4}    )(?:)-?(?:)(    [0-9]{2}    )(?:)-?(?:)(    [0-9]{2}    )(?:)'

GerHobbelt/xregexp,GerHobbelt/xregexp,mathiasbynens/xregexp,slevithan/XRegExp,mathiasbynens/xregexp,mathiasbynens/xregexp,slevithan/xregexp,mathiasbynens/xregexp,slevithan/xregexp,slevithan/xregexp,slevithan/XRegExp,GerHobbelt/xregexp