Formatting: Add 'white-space' as an allowed KSES CSS attribute.

The 'white-space' attribute is safe, has wide browser support, and is useful.

Props sukhendu2002, mukesh27, whyisjake..
Fixes #51707.


git-svn-id: https://develop.svn.wordpress.org/trunk@60671 602fd350-edb4-49c9-b593-d223f7449a82

Author: TimothyBJacobs

src/wp-includes/kses.php

@@ -2418,6 +2418,7 @@ function kses_init() {
  * @since 6.4.0 Added support for `writing-mode`.
  * @since 6.5.0 Added support for `background-repeat`.
  * @since 6.6.0 Added support for `grid-column`, `grid-row`, and `container-type`.
+ * @since 6.9.0 Added support for `white-space`.
  *
  * @param string $css        A string of CSS rules.
  * @param string $deprecated Not used.
@@ -2510,6 +2511,7 @@ function safecss_filter_attr( $css, $deprecated = '' ) {
 			'text-decoration',
 			'text-indent',
 			'text-transform',
+			'white-space',
 
 			'height',
 			'min-height',

tests/phpunit/tests/kses.php

@@ -1180,6 +1180,23 @@ public function data_safecss_filter_attr() {
 				'css'      => 'object-fit: cover',
 				'expected' => 'object-fit: cover',
 			),
+			// `white-space` introduced in 6.9.0.
+			array(
+				'css'      => 'white-space: nowrap',
+				'expected' => 'white-space: nowrap',
+			),
+			array(
+				'css'      => 'white-space: pre',
+				'expected' => 'white-space: pre',
+			),
+			array(
+				'css'      => 'white-space: pre-wrap',
+				'expected' => 'white-space: pre-wrap',
+			),
+			array(
+				'css'      => 'white-space: pre-line',
+				'expected' => 'white-space: pre-line',
+			),
 			// Expressions are not allowed.
 			array(
 				'css'      => 'height: expression( body.scrollTop + 50 + "px" )',