fix: The :not() selector not working when the argument has ID selector
fix: The :not() selector not working when the argument has ID selector

Fixes the bug that the :not() selector causes CSS parser error when the argument has
ID selector (#myid), child combinator (>), next-sibling combinator (+), or
subsequent-sibling combinator (~).

Fixes #769

vivliostyle/vivliostyle.js,vivliostyle/vivliostyle.js,vivliostyle/vivliostyle.js,vivliostyle/vivliostyle.js