Avoid [GlobalTitleFail] spam

Avoid [GlobalTitleFail] spam

MediaWiki::getTitle is checking, if a title is set on the context, but
that needs to call RequestContext::getTitle, which gives a warning, when
no title is set:

RequestContext::getTitle called by MediaWiki::getTitle with no title
set.

Adding a RequestContext::hasTitle function to check the title and avoid
the warning. Was added in I72c5c3fb75c9ceff02390c91b3735f2da90845de.

Change-Id: I4d8f8ef799cd91f0d2affe881019583ac77a31b7