scripting: replace '.size() == 0' with '.isEmpty()' (collections)

http://docs.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#isEmpty()
http://docs.oracle.com/javase/1.5.0/docs/api/java/util/ArrayList.html#isEmpty()

Change-Id: I76d8d8be2794655cb27ab121759494d7084b4744
Reviewed-on: https://gerrit.libreoffice.org/11967
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>