Passing non-existent object properties to `WP_UnitTestCase::assertNull()` produces notices, opt instead for `WP_UnitTestCase::assertTrue( empty( $obj->prop ) )` in `tests/db.php`.

See #25282.



git-svn-id: https://develop.svn.wordpress.org/trunk@25374 602fd350-edb4-49c9-b593-d223f7449a82
Suppress the `doing_it_wrong` notice from firing in `tests/phpunit/`tests/dependencies/jquery.php` when running in debug mode.

See #25282.



git-svn-id: https://develop.svn.wordpress.org/trunk@25375 602fd350-edb4-49c9-b593-d223f7449a82