Fix annotations display on 3rd-level nested comments

Steps to reproduce:

• Add an annotation.
• Reply to that annotation. (1st level of nested comments)
• Reply to that reply. (2nd level of nested comments)
• Reply to that reply. (3rd level of nested comments)
  => All annotations and replies disappear.
• Refresh the page.
  => Original annotation and first two levels of nested replies return. The last reply (3rd level) is lost.

It is still unclear what the expected behavior is – in Web UI, only 1 level of nested comments is possible.