Avoid an undefined index error in `tests/phpunit/tests/dependencies/styles.php`

See #25282.



git-svn-id: https://develop.svn.wordpress.org/trunk@25376 602fd350-edb4-49c9-b593-d223f7449a82
Fix the PHP 5.4 `Only variables should be passed by reference` notices in `tests/filters.php`.

See #25282.



git-svn-id: https://develop.svn.wordpress.org/trunk@25377 602fd350-edb4-49c9-b593-d223f7449a82
Suppress the deprecated function notice in `tests/formatting/CleanPre.php`

See #25282.



git-svn-id: https://develop.svn.wordpress.org/trunk@25378 602fd350-edb4-49c9-b593-d223f7449a82