Whitelist aria-hidden attribute in Sanitizer

Bug: T204618
Change-Id: I34b9b729eccd7658d5165b6661e5fd45a733b36c

RELEASE-NOTES-1.35

@@ -67,6 +67,8 @@ For notes on 1.34.x and older releases, see HISTORY.
 * …
 
 === New user-facing features in 1.35 ===
+* (T204618) Whitelisted the aria-hidden HTML attribute for all elements in
+  wikitext.
 * (T13456) Special:EditPage, Special:PageHistory, Special:PageInfo, and
   Special:Purge have been created as shortcuts for each action.
   Special:EditPage/Foo redirects to title=foo&action=edit, with PageHistory,

includes/parser/Sanitizer.php

@@ -1755,6 +1755,7 @@ class Sanitizer {
 			# WAI-ARIA
 			'aria-describedby',
 			'aria-flowto',
+			'aria-hidden',
 			'aria-label',
 			'aria-labelledby',
 			'aria-owns',

tests/phpunit/includes/parser/SanitizerTest.php

@@ -140,6 +140,10 @@ class SanitizerTest extends MediaWikiTestCase {
 				[ 'id' => 'foo bar', 'itemprop' => 'foo', 'content' => 'bar' ],
 				[ 'itemprop' => 'foo', 'content' => 'bar' ],
 			],
+			[ 'div',
+			  [ 'role' => 'presentation', 'aria-hidden' => 'true' ],
+			  [ 'role' => 'presentation', 'aria-hidden' => 'true' ],
+			],
 		];
 	}