gst/gstbin.c: Pass GType and size arguments to gst_iterator_new() in the right order (maybe we should make _new() tak...

Original commit message from CVS:
Reviewed by: Tim-Philipp Müller  <tim at centricular dot net>
* gst/gstbin.c: (gst_bin_iterate_sorted):
Pass GType and size arguments to gst_iterator_new() in the right
order (maybe we should make _new() take the GType as first argument
just like _new_list()?) (#318447).