Editor: Allow popover attributes in editor content.

Add attributes to KSES so that it's possible to create popover interactions natively in the editor. Adds `popovertarget`, `popovertargetaction` and `aria-haspopup` to `button`; `popover` to `div`, `ul`, and adds `dialog` with the attributes `open`, `closedby`, and `popover`.

Props harshdeepgill, jonsurrell, joedolson, sukhendu2002, flixos90, joedolson.
Fixes #61959.

git-svn-id: https://develop.svn.wordpress.org/trunk@60884 602fd350-edb4-49c9-b593-d223f7449a82

Author: joedolson

src/wp-includes/kses.php

@@ -109,10 +109,13 @@
 		),
 		'br'         => array(),
 		'button'     => array(
-			'disabled' => true,
-			'name'     => true,
-			'type'     => true,
-			'value'    => true,
+			'disabled'            => true,
+			'name'                => true,
+			'type'                => true,
+			'value'               => true,
+			'popovertarget'       => true,
+			'popovertargetaction' => true,
+			'aria-haspopup'       => true,
 		),
 		'caption'    => array(
 			'align' => true,
@@ -145,7 +148,13 @@
 			'open'  => true,
 		),
 		'div'        => array(
-			'align' => true,
+			'align'   => true,
+			'popover' => true,
+		),
+		'dialog'     => array(
+			'closedby' => true,
+			'open'     => true,
+			'popover'  => true,
 		),
 		'dl'         => array(),
 		'dt'         => array(),
@@ -362,7 +371,9 @@
 		'tt'         => array(),
 		'u'          => array(),
 		'ul'         => array(
-			'type' => true,
+			'type'    => true,
+			'popover' => true,
+			'role'    => true,
 		),
 		'ol'         => array(
 			'start'    => true,