The browser_web_channel.js test hangs when run under fission, because the iframe test fails, because WebChannel internally uses message managers.

Looks like this currently uses CPOWs for the eventTarget. I don't see them explicitly being used in mozilla-central. :vlad, do you know if these get used from fxa or something? What kind of values does it use (DOM nodes, I'm guessing? Right now it doesn't seem like anything is enforced...)

(In reply to :Gijs (he/him) from comment #1)

Looks like this currently uses CPOWs for the eventTarget. I don't see them explicitly being used in mozilla-central. :vlad, do you know if these get used from fxa or something? What kind of values does it use (DOM nodes, I'm guessing? Right now it doesn't seem like anything is enforced...)

Yes we use this for Fxa on Desktop and Firefox Preview on Android. WebChannels sends messages (JS Objects)

Examples here: https://github.com/mozilla/fxa-content-server/blob/master/docs/relier-communication-protocols/fx-webchannel.md

AFAIK we don't send DOM nodes as values.

From Slack:

vladikoff: this got refactored a bit, but we used event target to validate the source of the messages (like 4+ years ago) https://searchfox.org/mozilla-central/source/toolkit/actors/WebChannelChild.jsm#95

https://hg.mozilla.org/mozilla-central/rev/2a832a6aab1b

Retroactively moving fixed bugs whose summaries mention "Fission" (or other Fission-related keywords) but are not assigned to a Fission Milestone to an appropriate Fission Milestone.

This will generate a lot of bugmail, so you can filter your bugmail for the following UUID and delete them en masse:

0ee3c76a-bc79-4eb2-8d12-05dc0b68e732