Prevents an issue where passing `null` to HTML API constructors could result in runtime errors. Developed in https://github.com/WordPress/wordpress-develop/pull/9545. Props kraftbj, jonsurrell, westonruter. Fixes #63854. Built from https://develop.svn.wordpress.org/trunk@60887 git-svn-id: http://core.svn.wordpress.org/trunk@60223 1a063a9b-81f0-0310-95a4-ce76da25c4cd