Bug 1074095 - Return the last alt key object when the UserPress is on some empty area of alt char menu container.
Merge pull request #24537 from mnjul/bug_1074095_highlite_last_alt_key_at_container_area

Bug 1074095 - Return the last alt key object when the UserPress is on some empty area of alt char menu container. r=rudyl
Bug 1068236 - Follow-up, bump package.json r=kgrandon