[CssSelector] Increase specificity factors

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

TODO:
- [ ] fix the tests as they have not been updated yet

In the example here: http://www.w3.org/TR/selectors/#specificity a base of 10 is used, but it also notes:
> Concatenating the three numbers a-b-c __(in a number system with a large base)__ gives the specificity.

This commit fixes some edge cases, for example 0,1,11 (=21) should still have lower specificity then 0,2,0 (=20). This changes the value to respectively 111 and 200. So it's not perfect better, but can handle 10x as much.

Or are there any reasons this wasn't done before?