Docs: Corrections and improvements to types used in docblocks for symbols, properties, and filters.

See #53399


git-svn-id: https://develop.svn.wordpress.org/trunk@51298 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/customize/class-wp-customize-background-image-setting.php

@@ -20,7 +20,7 @@ final class WP_Customize_Background_Image_Setting extends WP_Customize_Setting {
 	/**
 	 * @since 3.4.0
 	 *
-	 * @param $value
+	 * @param mixed $value
 	 */
 	public function update( $value ) {
 		remove_theme_mod( 'background_image_thumb' );