Validation message about field length in drafts after changing focus doesn't disappear after deleting extra symbol

Steps to reproduce:

1. Open any branch and click 'Start Discussion' button.
2. Fill 'Topic title' and 'Message content' areas with maximum available number of symbols (120 - for 'Topic title', 20000 - for 'Message content').
3. Add 1 symbol to 'Topic title' and 'Message content' areas.
4. Delete 1 symbol from 'Topic title' and 'Message content' areas.

AR: Text is highlighted, error messages "Size must be between 1 and 120", "Size must be between 2 and 20000" are shown under text areas. Highlighting and error message disappear after deleting one more symbol (remaining 119 in 'Topic title', 19999 in 'Message content' area').
P.S.: Same behavior also observed for 'Poll' and 'Option list' fields.
ER: after deleting extra symbol error message isn't displayed, text isn't highlighted.
video: http://take.ms/jPo11