chore: remove unused class `electron::ObjectLifeMonitor` (#43089)
The last users were removed in June 2020 e1e73fa5f (#24115)
and May 2020 9d7ba982 (#23592).
Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Charles Kerr <charles@charleskerr.com>
* Use std::forward_list instead of base::LinkedList for better perf,
more consistent memory management. Better than std::list because we
don't need the double-linked-list behavior of std::list
* Use std::unordered_map instead of std::map for the v8 hash table
base::LinkedList does not delete its members on destruction. We need to
manually ensure the linkedlist is empty when the ObjectCache is
destroyed.
Fixes#27039
Notes: Fixed memory leak when sending non-primitives over the context
bridge
