Meta: do not export incumbent settings object

This will discourage people from using it, helping with #1430. Closes #4229 by superseding it. Note that entry is already non-exported.

Author: domenic

source

@@ -89094,8 +89094,7 @@ interface <dfn>BeforeUnloadEvent</dfn> : <span>Event</span> {
   <span>JavaScript execution context stack</span> that has a non-null ScriptOrModule component, or
   null if there is no such entry in the <span>JavaScript execution context stack</span>.</p>
 
-  <p>With all this in place, the <dfn export>incumbent settings object</dfn> is determined as
-  follows:</p>
+  <p>With all this in place, the <dfn>incumbent settings object</dfn> is determined as follows:</p>
 
   <ol>
    <li><p>Let <var>context</var> be the <span>topmost script-having execution