Bug 1035321 - Send the accuracy of locations to Find My Device's server.

This also imports mock_l10n.js from bug 1004973, since the tests introduced
in this patch depend on that file.
Bug 1037338 - Installed apps arent added to smart collection
Merge pull request #21706 from etiennesegonzac/bug-1029979

Bug 1029979 - TonePlayer: prevent successive trash/ensureAudio() calls from creating an AudioContext with a null channel r=gsvelto
Bug 1011016; new marketplace dev/stage packages