The following pieces of state currently stored in documents needs to be replicated onto some cross-process synced structure (BrowsingContext, TabContext) for bug 1575356:

A boolean flag caching the value of the "HasSecureConnection" check.
A boolean flag caching the value of the "AllowsMixedContentAndConnectionData" check.

Tentatively moving all bugs whose summaries mention "Fission" (or other Fission-related keywords) but are not assigned to a Fission Milestone to the "?" triage 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

Kannan says replacing nsIDocShellTreeItem calls should block enabling Fission in Nightly (M6).

Blocks Fission dogfooding (M5).

Tracking for Fission Nightly (M6) because this bug doesn't need to block dogfooding.

Christoph, is this a Content Security bug? Kannan found this problem as part of his nsIDocShellTreeItem removal analysis for Fission. I don't know how this bug affects Fission users.

Yeah, I'll mark it block the Meta DOM:Security Fission Bug and we will look into it.

Auditing whether this use of nsIDocShellTreeItem breaks when Fission is enabled blocks Fission Nightly.

There were several bugs which have updated the problems described in comment 0. I guess most accurately is to mark this bug as a duplicate of Bug 1575356.

Clearing Fission Milestone for bugs resolved as duplicates. We don't need to track duplicates.