http://trac.webkit.org/changeset/72211 (bug https://bugs.webkit.org/show_bug.cgi?id=48518) introduced this test, but it does not pass on the GTK WebKit port. It looks like the Geolocation test infrastructure for WebKit GTK still needs some additions before many of the Geolocation tests will pass.
*** This bug has been marked as a duplicate of bug 36053 ***