[css-color-4] restrict type of ICC profile, fix w3c#6024

Author: svgeesus

css-color-4/Overview.bs

@@ -3744,10 +3744,22 @@ Specifying a color profile: the ''@color-profile'' at-rule</h3>
 
 	The '@color-profile/src' descriptor specifies the URL to retrieve the color-profile information from.
 
+	The retrieved ICC profile is valid if
+
+	- it can be parsed as an ICC Profile
+
+	- it is an Input, Display, Output, or ColorSpace ICC profile. (Abstract, DeviceLink, and NamedColor ICC Profiles must not be used).
+
+	If the profile is not valid, all CSS colors
+	which reference this profile
+	are <a>invalid color</a>s.
+
 	Note: The Internet Media Type ("MIME type")
 	for ICC profiles is
 	<a href="https://www.iana.org/assignments/media-types/application/vnd.iccprofile">application/vnd.iccprofile</a>.
 
+
+
 	<!-- should we add a format field to this descriptor, like with font-face src? it is always ICC format
 	in practice, but that could change in the future. or we could add format later, once there is
 	a need, and make the default ICC if not specified -->