Due to changes in how processes are selected when doing BFCached
navigations, the process will be re-used for the navigation meaning we
no longer need to add logic explicitly keeping it alive.
This also tweaks the code which checks this to explicitly stop checking
any keepProcessesAlive prefs for these origin-specific remote types.
Differential Revision: https://phabricator.services.mozilla.com/D220191
c3f1f22978