Deprecate calling FileDeleteForm::doDelete without passing a user

Bug: T245682
Change-Id: I33dc25401251f057f3db7d7b69f5ced00a86f896

RELEASE-NOTES-1.35

@@ -489,6 +489,7 @@ because of Phabricator reports.
   - LogEventsList::userCanBitfield
   - LogEventsList::userCanViewLogType
   - LogPage::addEntry
+  - FileDeleteForm::doDelete
 * Article::insertProtectNullRevision is deprecated. Instead, use
   WikiPage::insertProtectNullRevision.
 * …

includes/FileDeleteForm.php

@@ -178,7 +178,8 @@ class FileDeleteForm {
 	 * @param ?string &$oldimage Archive name
 	 * @param string $reason Reason of the deletion
 	 * @param bool $suppress Whether to mark all deleted versions as restricted
-	 * @param User|null $user User object performing the request
+	 * @param User|null $user User object performing the request (null defaults to $wgUser
+	 *        and is deprecated as of 1.35)
 	 * @param array $tags Tags to apply to the deletion action
 	 * @throws MWException
 	 * @return Status
@@ -187,6 +188,7 @@ class FileDeleteForm {
 		$suppress, User $user = null, $tags = []
 	) {
 		if ( $user === null ) {
+			wfDeprecated( __METHOD__ . ' without passing a $user parameter', '1.35' );
 			global $wgUser;
 			$user = $wgUser;
 		}