annotation: remove empty comment on losing focus

[lpranam]

problem: when try to insert comment and comment field is empty, click on some other comment, it will cause an empty comment insertion in DOM which can not be removed until doc reload. This subsequently prevented new comment insertion.

Change-Id: Idccf77d29730a3ca81ecf8ba2c3c9e4d6029a3e3

• Target version: master

Checklist

• [ ] Code is properly formatted
• [ ] All commits have Change-Id
• [ ] I have run tests with make check
• [ ] I have issued make run and manually verified that everything looks okay
• [ ] Documentation (manuals or wiki) has been updated or is not required

[gokaysatir]

I think we can search for a better reproducer. Commented on the internal task also. Thanks:)

[lpranam]

consistent reproducing step:

1. insert a few comments normally
2. try to insert new comments but don't add any text into textbox, and click on some other comment

[lpranam]

closed in favor of https://github.com/CollaboraOnline/online/pull/8402