Remove ContentHandler::cleanupHandlersCache

It has been deprecated since 1.35 and it is unused.

Change-Id: I3a9e207d1e4cd8d2d3386934926299427d11785f

RELEASE-NOTES-1.39

@@ -278,6 +278,7 @@ because of Phabricator reports.
 * SpecialMute::isTargetBlacklisted(), deprecated in 1.35, has been removed. Use
   ::isTargetMuted() instead.
 * WebRequest::checkUrlExtension(), deprecated in 1.35, has been removed.
+* ContentHandler::cleanupHandlersCache(), deprecated in 1.35, has been removed.
 * …
 
 === Deprecations in 1.39 ===

includes/content/ContentHandler.php

@@ -283,19 +283,6 @@ abstract class ContentHandler {
 			->getContentHandler( $modelId );
 	}
 
-	/**
-	 * @deprecated since 1.35, hard deprecated since 1.37
-	 * Please, use ContentHandlerFactory. Cleanup is not needed
-	 * @see ContentHandlerFactory
-	 *
-	 * Clean up handlers cache.
-	 */
-	public static function cleanupHandlersCache() {
-		wfDeprecated( __METHOD__, '1.35' );
-		// No-op: no longer needed, since the instance cache is in the
-		// ContentHandlerFactory service, and services get reset between tests
-	}
-
 	/**
 	 * Returns the localized name for a given content model.
 	 *