Merge branch 'hotfix/3307'

Close zendframework/zendframework#3307

src/Translator/Plural/Rule.php

@@ -205,7 +205,7 @@ public static function fromString($string)
         $tree = static::$parser->parse($match['plural']);
         $ast  = static::createAst($tree);
 
-        return new self($numPlurals, $ast);
+        return new static($numPlurals, $ast);
     }
 
     /**