Code Editor: Define default gutters and toggle lint markers based on changes to lint option.

Explicitly define `gutters` in base `defaultSettings` to improve merges of multiple calls to `wp_enqueue_code_editor()`.

Props westonruter, georgestephanis for testing.
Amends [41974].
See #12423.

Built from https://develop.svn.wordpress.org/trunk@41992


git-svn-id: http://core.svn.wordpress.org/trunk@41826 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/general-template.php

@@ -3157,6 +3157,7 @@ function wp_enqueue_code_editor( $args ) {
 				'Alt-F' => 'findPersistent',
 			),
 			'direction' => 'ltr', // Code is shown in LTR even in RTL languages.
+			'gutters' => array(),
 		),
 		'csslint' => array(
 			'errors' => true, // Parsing errors.