Sequential numbers aren't great because they change when an earlier
comment is archived. Parent comment/heading IDs should change less
often.
This also makes much more sense for disambiguating subsections,
e.g. a dozen identical ===Votes=== sections for a dozen proposals.
Bug: T264478
Change-Id: I466454984fd919ebef35f2b37ddb5d86dc842996
Previously, only comments could have IDs, because we only needed IDs
for replying. But we might also use them for notifications soon.
Bug: T264478
Change-Id: I1bcad02bf17ab54bc5028a959543c10f0430836b
When adding a reply, we take a node at the end of the previous comment,
compare that comment's indentation level to the expected indentation level
of the reply, and add (or remove) that number of wrapper lists.
The existing code did not consider that comments may have lists within
them, and so the indentation of that node may not match the indentation
of the comment.
Bug: T252702
Change-Id: Icc5ff19783d2b213bff99f283cb0599a8b5c1ab4
