typo in @cover statement

PHP Code Coverage uses the @cover comment statement to limit code
coverage to some specific function.  The method reference lacked the
trailing 's' leading to an error when running coverage:

PHP_CodeCoverage_Exception: Trying to @cover not existing method
"Title::checkReadPermission".

Change-Id: Ie09e804039271ec8f0165c32dc7849ea4be8a3b9