gtk_widget_style_get requies the use of NULL as a call sentinel much like in g_object_get and g_object_set.
Created attachment 77695 [details]
Unfortunately this patch does not remove all of the false positives from RenderThemeGtk. It seems that check-webkit-style does not always handle multi-line function calls properly.
Committed r74809: <http://trac.webkit.org/changeset/74809>