Style computed value of a URL is returning the relative URL

[asajeffrey]

If you call style.computed_value_to_string(some-url-valued-property) then you get the original, possibly relative, URL rather than the computed absolute URL. The culprit is

servo/components/style/servo/url.rs

Lines 113 to 121 in f18782f

	let string = match self.original {
	Some(ref original) => &**original,
	None => match self.resolved {
	Some(ref url) => url.as_str(),
	// This can only happen if the url wasn't specified by the
	// user *and* it's an invalid url that has been transformed
	// back to specified value via the "uncompute" functionality.
	None => "about:invalid",
	}

, which prioritizes the original URL, together with the fact that we share code between specified and computed URLs.

[asajeffrey]

IRC conversation with @nox http://logs.glob.uno/?c=mozilla%23servo&s=6+Jul+2017&e=6+Jul+2017#c709184