[css-display] Remove ref to empty elements, to avoid implying special behavior.

Author: tabatkins

css-display/Overview.bs

@@ -483,9 +483,8 @@ Box Generation: the ''display/none'' and ''display/contents'' keywords</h3>
 			are not affected.
 
 			This value is treated as ''display: none'' on replaced elements,
-			form controls
-			(such as <a href="https://html.spec.whatwg.org/multipage/forms.html#category-submit">submittable elements</a> in [[HTML]]),
-			and (obviously) empty elements.
+			and form controls
+			(such as <a href="https://html.spec.whatwg.org/multipage/forms.html#category-submit">submittable elements</a> in [[HTML]]).
 			The effect is exactly as if the UA style sheet had specified
 			''display: none !important'' on such elements,
 			except that the computed style is still ''contents''.