Accessibility: Avoid a keyboard trap on the permalink custom structure setting.

Using the `focus` event on the permalink custom structure field made impossible
to navigate through all the form fields using only the keyboard without actually
selecting the custom structure setting. Instead, using click and input preserves
the original functionality when using any kind of pointing or input device.

Also changes `attr()` to `prop()`` as recommended for a `checked` property.

Fixes #40982.

Built from https://develop.svn.wordpress.org/trunk@40897


git-svn-id: http://core.svn.wordpress.org/trunk@40747 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/options.php

@@ -100,8 +100,8 @@ jQuery(document).ready(function() {
 			return;
 		jQuery('#permalink_structure').val( this.value );
 	});
-	jQuery('#permalink_structure').focus(function() {
-		jQuery("#custom_selection").attr('checked', 'checked');
+	jQuery( '#permalink_structure' ).on( 'click input', function() {
+		jQuery( '#custom_selection' ).prop( 'checked', true );
 	});
 });
 </script>

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-40896';
+$wp_version = '4.9-alpha-40897';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.