conflict between `:not` and `:before`

[zbryikt]

say for scoping in hierarchy we use [scope] selector for scoping test, thus csscope generates css with :not([scope]) selector. This may apply to rules with pseudo elements ( :before ) - but it just doesn't work:

something::before:not([scope])  /* this won't work, and will break this rule */

however we simply don't need :not([scope]) for pseudo elements since they can never be targets for matching scope test.

We can simply ignore the scope test for pseudo elements to resolve this issue.