[cssom] Serializing url values

Hi All,

I had a quick question about how url values are serialized for the image type [1] (or in general).

The questions I have are:
1. Does the serialized version of the url() notation quote its URL? Does it preserve the quoted form of the URL? The spec allows for optionally single or double quoting it [2].
2. Are relative URLs resolved to absolute URLs?

For the last point, I'm unclear on whether the url notation would follow the "Serialize a URL" common idiom [3] or "Serialize a URI" component value [4] rule, as neither seems to be a perfect fit. To me, the best fit definition would be a url function taking either a string or a uri, but I did not see a general rule for serializing functions.

-Bear

[1] http://dev.w3.org/csswg/css-images-3/#image-type
[2] http://www.w3.org/TR/CSS21/syndata.html#uri
[3] http://dev.w3.org/csswg/cssom/#serialize-a-url
[4] http://dev.w3.org/csswg/cssom/#serializing-css-values