Remove nasty ancient global $title (at least $wgTitle is easier to grep for), its no longer set since
r78512. Afaict, this generic-named global is no longer in core.
It's not a title object, it's a string of what title= in the URL. If you want that, use WebRequest::getText() or something. Using this string is *wrong* and any extensions should be fixed (I didn't check because $title is a PITA to grep for). Don't backport to 1.17 because this is trivial, harmless, and may Break Something.
(Also made fileCachedPage private since it has no outside callers and I can't see any reason why you should)