Remove UTF-8 string length workaround
Remove UTF-8 string length workaround

Summary: Should no longer be needed after the previous diff, as the ResStringPool code has been updated to properly return lengths.

Reviewed By: NTillmann

Differential Revision: D37250650

fbshipit-source-id: b41e75e131c67cac12840d9750489e66928bea0f

facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex