[Runtime] Fix Tizen IVI build error for PR#1593.
IVI buildbot reports error:
'xwalk::application_widget_keys::kIcon128Key' has a previous declaration
as 'const char xwalk::application_widget_keys::kIcon128Key []'

This PR fix above error.
Merge pull request #1640 from shaochangbin/fix_build_error

[Runtime][IVI] Fix Tizen IVI build error by PR#1593.