This patch is making sure that `context.active` is going to be `false` when an extension page
has been moved into the bfcache because the `browser` element where it was loading into has been navigated
to a page that needs to run in a different process.
This also match the expected behavior for a same process navigation (e.g. an extension page being navigated
to another extension page) and the changes in this patch do also fix Bug 1499129 which was already happening
for same process navigations (and it does the same also for an extension page moved to the bfcache because
of a cross-process navigation case tracked by this bug).
The test case included in this patch cover both same-process and cross-process navigations under fission
and non fissions jobs.
Differential Revision: https://phabricator.services.mozilla.com/D145919
1915f507fa