TinyMCE: Improve the previews for shortcodes.

git-svn-id: https://develop.svn.wordpress.org/trunk@41395 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/script-loader.php

@@ -1058,6 +1058,10 @@ function wp_just_in_time_script_localization() {
 		'autosaveInterval' => AUTOSAVE_INTERVAL,
 		'blog_id' => get_current_blog_id(),
 	) );
+
+	wp_localize_script( 'mce-view', 'mceViewL10n', array(
+		'shortcodes' => ! empty( $GLOBALS['shortcode_tags'] ) ? array_keys( $GLOBALS['shortcode_tags'] ) : array()
+	) );
 }
 
 /**