Themes: Support additional link related pseudo classes in `theme.json`.

This changeset adds support for `:link` and `:any-link` in `theme.json`, using the `VALID_ELEMENT_PSEUDO_SELECTORS` array. `:link` can be used to style unvisited links and `:any-link` can be used to style any link containing an `href` attribute.

Props peterwilsoncc, whaze, audrasjb, costdev, mukesh27.
Fixes #57053.

Built from https://develop.svn.wordpress.org/trunk@55121


git-svn-id: http://core.svn.wordpress.org/trunk@54654 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-theme-json.php

@@ -408,18 +408,20 @@ class WP_Theme_JSON {
 	/**
 	 * Defines which pseudo selectors are enabled for which elements.
 	 *
-	 * The order of the selectors should be: visited, hover, focus, active.
-	 * This is to ensure that 'visited' has the lowest specificity
-	 * and the other selectors can always overwrite it.
+	 * The order of the selectors should be: link, any-link, visited, hover, focus, active.
+	 * This is to ensure the user action (hover, focus and active) styles have a higher
+	 * specificity than the visited styles, which in turn have a higher specificity than
+	 * the unvisited styles.
 	 *
 	 * See https://core.trac.wordpress.org/ticket/56928.
 	 * Note: this will affect both top-level and block-level elements.
 	 *
 	 * @since 6.1.0
+	 * @since 6.2.0 Added support for ':link' and ':any-link'.
 	 */
 	const VALID_ELEMENT_PSEUDO_SELECTORS = array(
-		'link'   => array( ':visited', ':hover', ':focus', ':active' ),
-		'button' => array( ':visited', ':hover', ':focus', ':active' ),
+		'link'   => array( ':link', ':any-link', ':visited', ':hover', ':focus', ':active' ),
+		'button' => array( ':link', ':any-link', ':visited', ':hover', ':focus', ':active' ),
 	);
 
 	/**

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.2-alpha-55120';
+$wp_version = '6.2-alpha-55121';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.