As far as I'm aware, this is currently not possible, however, there is currently work going on to add support for generic factory patterns, see this issue on their issue-tracker:
http://youtrack.jetbrains.com/issue/WI-6027
The PhpStorm developers welcome new feature requests on their issue tracker and are quite responsive. So you may file a feature request
Also, this may be related to your question: http://youtrack.jetbrains.com/issue/WI-5304