Wikimedia Bugzilla is closed!

Created attachment 4547 [details]
proposed patch

When using ExpandTemplates with an old preprocessor parser and checking "Show XML parse tree", like with Wikimedia sites (i think), the output is a blank screen as the extension try to call an undefined function Parser_OldPP::preprocessToDom(). I modified the extension to ckeck if that function is aviable, and, if not to not show that check box. I also modified it to use $wgSpecialPages to register the special page instead of extAddSpecialPage().