[selectors-4][meta] Mark legacy unexported.

Author: tabatkins

selectors-4/Overview.bs

@@ -3822,7 +3822,7 @@ Changes</h2>
 				Issue: Need to define tree for XML.
 				<li>[[#api-hooks]]
 					<ul>
-						<li>Note that earlier versions of this section defined a section on <dfn id="evaluating-selectors">evaluating a selector</dfn>,
+						<li>Note that earlier versions of this section defined a section on <dfn noexport id="evaluating-selectors">evaluating a selector</dfn>,
 						but that section is no longer present.
 						Specifications referencing that section should instead reference
 						the algorithm to <a>match a selector against a tree</a>.