Fall back to non-translated strings in _doing_it_wrong() if the translation function doesn't exist. This may be the case in sunrise, for example.

props SergeyBiryukov.
fixes #23555.
for trunk.



git-svn-id: http://core.svn.wordpress.org/trunk@24439 1a063a9b-81f0-0310-95a4-ce76da25c4cd