Add jQuery.escapeSelector

[timmywil]

See jquery/jquery#1761

Document the new method jQuery.escapeSelector, for escaping strings for use in selectors. Much the same as the native CSS.escape, but replaces the null character with U+FFFD, rather than throwing an error.

[gibson042]

Much the same as the native CSS.escape, but replaces the null character with U+FFFD, rather than throwing an error.

Actually, it's identical to CSS.escape as specified in the current CSSOM draft (cf. https://drafts.csswg.org/cssom/#serialize-an-identifier ), which was updated when I raised the issue. :)

[timmywil]

What @gibson042 said. I misunderstood.

[timmywil]

So, I assume MDN needs an update.