edje: Reduce duplicated item obj creations and deletions.

edje: Reduce duplicated item obj creations and deletions.

Summary:
When text is changed, all of objects for item tag are deleted
and recreated. It is unnecessary work and can cause performance
issues. Actually, many of application developers wonder why
item provider callback functions are called every text changes.
@fix

Test Plan:
Run elementary_test -to "entry emoticon"
When you make a very little change on text,
36 emoticon objects are recreated.

Reviewers: woohyun, jaehwan, herdsman, tasn

Reviewed By: tasn

Subscribers: cedric, jpeg

Differential Revision: https://phab.enlightenment.org/D3537