[css-font-loading-3] FontFaceSet.clear() should not clear CSS-connected items (w3c#6553)

Author: litherum

css-font-loading-3/Overview.bs

@@ -550,7 +550,7 @@ The <code>FontFaceSet</code> Interface</h2>
 			When the {{clear()}} method is called,
 			execute the following steps:
 
-			1. Remove all items from the {{FontFaceSet}}’s [=FontFaceSet/set entries=],
+			1. Remove all non-<a>CSS-connected</a> items from the {{FontFaceSet}}’s [=FontFaceSet/set entries=],
 				its {{[[LoadedFonts]]}} list,
 				and its {{[[FailedFonts]]}} list.
 			2. If the {{FontFaceSet}}’s {{[[LoadingFonts]]}} list is non-empty,