[css-ui-4] Markup fix

Author: frivoal

css-ui-4/Overview.bs

@@ -2016,7 +2016,7 @@ that are typical of the element whose appearance it acquires.
 	and activating (for example by clicking) the element would toggle the state as usual.
 </div>
 
-For compatibility with legacy content, UAs must also support <dfn type=property export>-webkit-appearance</dfn>
+For compatibility with legacy content, UAs must also support <dfn property export>-webkit-appearance</dfn>
 as a [=legacy name alias=] of 'appearance'.
 
 <h3 id=control-specific-rules>