1. Extend the JS modifier to allow adding top-level comments
(that is, replies to headings). PHP modifier doesn't do this
because we'll save the changes using paction=addtopic instead.
2. Subclass CommentController to allow adding a new heading and a
top-level comment underneath it at the same time.
3. A lot of ugly code in ReplyWidget to customize the interface
for this case. Much of it should probably be moved to
CommentController/NewTopicController.
Bug: T267595
Change-Id: I9c707bb7f7aae1b92c72fb4dee436490f8c8409b
We avoided fixing these because it causes changes in just about all of
the test data, which is annoying when reviewing or blaming changes.
But the previous several commits also caused changes in just about all
of the test data, so we might as well do this too.
Change-Id: I83b64d83b6f12c04dc06c0cadff7cdd89417e137
Our threads now also contain all replies to their sub-threads.
This is similar to how sections work in MediaWiki, where the parent
section also contains the content of all the lower-level sections.
We're going to need this for notifications about replies in a thread.
Bug: T264478
Change-Id: I241fc58e2088a7555942824b0f184ed21e3a8b6f
