add "has" function (parent selector)

[gajus]

• CSS does not have a parent selector.
• cheerio has has() selector.

Since we want Surgeon to work across different environment (i.e. browser), we'd need to implement this on the Surgeon level.

Use case

Sometimes it is required to know whether an element has a descending element to know if it is the right element, e.g. http://www.mk2.com/salles/mk2-gambetta.

To select all table rows that contain movie information, we can check if a table row includes information about the movie name.

#seances .l-mk2-tables .l-session-table .fiche-film-info::has(.fiche-film-title)