This bug was revealed by http://trac.webkit.org/changeset/55275 http://build.webkit.org/results/Qt%20Linux%20Release/r55275%20%287849%29/results.html Our LayoutTestController.numberOfPages hasn't got default parameters as the platform independent LayoutTestController.numberOfPages.
Created attachment 49577 [details] proposed patch
Landed in http://trac.webkit.org/changeset/55280 .