replaceAll.php: Replace get_class with instanceof

The User class was namespaced in 1d0b7ae1,
checking class names as string is broken, use instanceof.
There are no subclasses of User class to ignore at this point.

Also use User::getName instead of implicit User::__toString

Change-Id: I8b9f73609a7ef9f781c8a5ae27e00d612d33ee4f

maintenance/replaceAll.php

@@ -30,6 +30,7 @@
 namespace MediaWiki\Extension\ReplaceText;
 
 use Maintenance;
+use MediaWiki\User\User;
 use MWException;
 
 $IP = getenv( 'MW_INSTALL_PATH' ) ?: __DIR__ . '/../../..';
@@ -112,7 +113,7 @@ class ReplaceAll extends Maintenance {
 			$userFactory->newFromId( $userReplacing ) :
 			$userFactory->newFromName( $userReplacing );
 
-		if ( get_class( $user ) !== 'User' ) {
+		if ( !$user instanceof User ) {
 			$this->fatalError(
 				"Couldn't translate '$userReplacing' to a user."
 			);
@@ -437,7 +438,7 @@ EOF;
 				$this->botEdit = true;
 			}
 			if ( !$this->getReply(
-				"Attribute changes to the user '{$this->user}'?$comment"
+				"Attribute changes to the user '{$this->user->getName()}'?$comment"
 			) ) {
 				return;
 			}