video-texture: Remote the dispose vfunc
video-texture: Remote the dispose vfunc

Nothing needs it, so just remove it.

GNOME/clutter-gst,ystreet/clutter-gst,GNOME/clutter-gst,ystreet/clutter-gst,GNOME/clutter-gst,lubosz/clutter-gst,lubosz/clutter-gst,GNOME/clutter-gst,skinkie/clutter-gst,skinkie/clutter-gst,skinkie/clutter-gst,ystreet/clutter-gst,lubosz/clutter-gst,ystreet/clutter-gst