Editorial: correct 'callback interface' cross-reference

Author: Ms2ger

index.bs

@@ -10887,7 +10887,7 @@ the [=interface=]’s [=qualified name=] and the string "<code>Prototype</code>"
 
 <h4 id="legacy-callback-interface-object">Legacy callback interface object</h4>
 
-For every callback [=interface=] that is [=exposed=] in
+For every [=callback interface=] that is [=exposed=] in
 a given ECMAScript global environment
 and on which [=constants=] are defined,
 a corresponding property must exist on the ECMAScript environment's global object.