Automatic changes by ESLint, except for manual corrections for .xml files.
Differential Revision: https://phabricator.services.mozilla.com/D4439
--HG--
extra : moz-landing-system : lando
NOTE: The '__SSi' and '__SS_lastSessionWindowID' properties on windows are kept,
because they are expected to stick around longer during application shutdown.
The benefits is are:
1. Cleaner code - Sessionstore implementation details are not leaked outside its
module.
2. Observing the lifetime of objects becomes unnecessary, because the WeakMaps are
cleaned up when objects are GC'd, making leakage of their references impossible
and Sessionstore can't hold objects hostage anymore.
3. Simplification - all state is now maintained in SessionStore.jsm, which allows
for additional refactoring later on to simplify the implementation further.
MozReview-Commit-ID: C1II8qHkQ6F
--HG--
extra : rebase_source : e5fc6984558bd455a33e275f7060d42c93c21720
