Rename language codes sr-ec and sr-el to sr-cyrl and sr-latn

Authored by Fomafix on Nov 23 2016, 4:58 PM.

Description

Rename language codes sr-ec and sr-el to sr-cyrl and sr-latn

This change requires I75da0af35a2066e7963e50c56c99daf1e07c55e6 in core.

This change readds the tests with the language codes 'sr' that get temporary
disabled by Idca04cd5b1f9b362f89a7b7b3581c5f5736b88c5.

Bug: T117845
Depends-On: I75da0af35a2066e7963e50c56c99daf1e07c55e6
Change-Id: I7eaee0170a8d4938c94d1024f9e6f58c94db9c3d