fix for bnc#819865 itemstate in parent style incorrectly reported as set

Problem occurs because attrs set with default values are reported as set when queried

Change-Id: I89d6c3b09312fb78052d87ff20aa12c6fbe7bc98
(cherry picked from commit bf8e9b29aaebcbdd8f2f06b42ac97b8d9f8f4503)

Signed-off-by: Andras Timar <andras.timar@collabora.com>