Merge pull request #13687 from ian-liu/l10n/Bug936812_Missing_strings_in_en-US_properties_bluetooth_dialer_system

Bug 936812 - Missing strings in en-US properties (bluetooth, dialer, system), r=@etiennesegonzac
(cherry picked from commit bdfb965ead3c0b0aa63c9b0394632fcadd73e6ba)