[css-color-5][editorial] trim old comment on early color-mix implementation status

Author: svgeesus

css-color-5/Overview.bs

@@ -778,27 +778,6 @@ which is rgb(52.446% 45.821% 62.953%)
 </div>
 -->
 
-<!-- color-mix() IMPLEMENTATIONS
-
-	Chrome, sRGB only for now
-	Implement basic color-mix() functionality, and expose it to chrome code and to content behind a pref.
-	https://bugzilla.mozilla.org/show_bug.cgi?id=1695376
-
-	Gecko,
-	Implement CSS color-mix function
-	https://bugzilla.mozilla.org/show_bug.cgi?id=1682436
-
-	DevTools should understand the color-mix() function
-	https://bugzilla.mozilla.org/show_bug.cgi?id=1695382
-
-	[Closed] Implement basic color-mix() functionality, and expose it to chrome code and to content behind a pref.
-	https://bugzilla.mozilla.org/show_bug.cgi?id=1695376
-
-	WebKit
-	Implemented, shipped in Safari 15.0 as experimental
-
--->
-
 
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