Re: [css3-syntax] CSS escape sequences

> If you're proposing paving cowpaths... is this what UAs actually do?

Except for Gecko, yes.

> How do they handle unpaired surrogates?  Surrogates in the wrong order?

Let’s find out: http://jsfiddle.net/mathias/wvPdr/

In Gecko, Presto, Trident and WebKit, unpaired surrogates like
`\ud83d\uffff ` are displayed as `ud83fduffff`, i.e. the backslash
just makes the `u` character literal.

Gecko, Opera and IE treat a surrogate pair in the wrong order as
invalid and replace it with two U+FFFD characters. This seems like the
most sensible thing to do.
Only WebKit differs here: it discards the entire `content` declaration.