The issue here is that authorStyleDisabledDefault persists on the BrowsingContext.
This means it stays set/unset if the BC navigates same-origin (including
reloads). But the actor was keeping its own copy, on the actor, and the actor
gets destroyed in those circumstances, leading to the frontend and the internal
state no longer being in sync.
This patch addresses this by no longer keeping our own state and just reading
the browsingcontext's field directly.
This is a tiny bit hackish because technically, whether this is the 'default'
is not the same as whether the author style is actually disabled, but in
practice the child actor always sets the two at the same time, and it is
the simpler fix (vs. trying to mirror state to the parent some more).
Differential Revision: https://phabricator.services.mozilla.com/D183188
a9a933fb6c