widget: fix seg fault when ts is NULL.
widget: fix seg fault when ts is NULL.

Summary:
if translatable is FALSE and _translate_string_data_get returns NULL, ts
would be NULL which results into crash.

@fix

Reviewers: seoz, raster, Hermet

Reviewed By: Hermet

Subscribers: seoz

Differential Revision: https://phab.enlightenment.org/D1543

FlorentRevest/Elementary,tasn/elementary,tasn/elementary,tasn/elementary,FlorentRevest/Elementary,tasn/elementary,tasn/elementary,rvandegrift/elementary,FlorentRevest/Elementary,rvandegrift/elementary,FlorentRevest/Elementary,rvandegrift/elementary,rvandegrift/elementary