Set the `core/router` state `url` property with the current page URL using `get_self_link()` when the first `data-wp-router-region` directive is processed, so that the stores subscribing to that property already have the correct value on page load. Props westonruter. Fixes #64649. Built from https://develop.svn.wordpress.org/trunk@61659 git-svn-id: http://core.svn.wordpress.org/trunk@60970 1a063a9b-81f0-0310-95a4-ce76da25c4cd