tests: scimoz: make headless scintilla have a main window (sort of)
http://bugs.activestate.com/show_bug.cgi?id=102147

This is necessary to ensure that it correctly allocates surfaces, which in
turn will ensure that scintilla will lay out correctly.

(integrated from komodo (trunk) change 83694 by marky)

git-svn-id: http://svn.openkomodo.com/repos/openkomodo/trunk@14187 b87d16e7-d29f-4ee1-b5ec-817d645d335f