Otherwise it may be undefined, and we DO create default-constructed
PollHandler. For example, one is used as a fallback poll object
in NeoChatRoom::poll.
This is blind fix for a pretty nasty poll-related crash we saw a few
months ago.
BUG: 493649
(cherry picked from commit 5ef66b5cf6)
Refactor PollHandler to make it more reliable. This ended up with much more code than I expected as the original intent was just to stop a crash when switching rooms.
- Using a event string was flaky, changing to using an event reference is more reliable.
- Since we're only creating them from NeoChatRoom there is no need to to be able to set properties from QML so only read properties.
- Pass from the MessageEventModel rather than an invokable method.
- Create a basic test suite
- Create properties in PollHandler to remove the need to use content in PollDelegate, this means content is no longer a required role.
