Check for instanceof Title

Mail from Cicalese, Cindy:

Tested on MediaWiki 1.21 and 1.22 throws PHP Fatal error:  Call to a member function isSpecialPage() on a non-object in …/mediawiki/extensions/SemanticResultFormats/formats/tagcloud/TagCloud.php on line 80

 I get this error if I include any tagcloud in my wiki. An example is the following:

```
{{#ask:[[Tags::+]]
|?Tags
|format=tagcloud
|template=TagTagCloud
|maxtags=75
|limit=10000
}}