Bug 975486 - [B2G][l12y][Settings]Serbian-Cyrillic: Keyboard title is
truncated in 'Selected Keyboards' list.
 - Shorten the string of Serbian Cyrillic.
Merge pull request #16986 from RudyLu/Bug975486-shorten_serbian_Cyrillic_string

Bug 975486 - [B2G][l12y][Settings]Serbian-Cyrillic: Keyboard title is
r=civas