Test parsing of CSS nth-child tokens.

TEST DID NOT COMPLETE

Rules from the stylesheet:

Expected result:

#a:nth-child(n) { color: green; }
#b:nth-child(n) { color: green; }
#c:nth-child(n) { color: green; }
#d:nth-child(-n) { color: green; }
#e:nth-child(-n) { color: green; }
#f:nth-child(n) { color: green; }
#g:nth-child(n) { color: green; }
#h:nth-child(n) { color: green; }
#i:nth-child(-n) { color: green; }
#j:nth-child(-n) { color: green; }
#l:nth-child(-n-123) { color: green; }
#m:nth-child(n-123) { color: green; }
#o:nth-child(23n+123) { color: green; }
#t:nth-child(n+3) { color: green; }
#u:nth-child(n+7) { color: green; }