Bug 917480 - Pre: commenting. r=nalexander
Bug 917480 - Part 0: refactor checking of isGeckoPref inside GeckoPreferences. r=liuche
Bug 917480 - Part 1: add basic locale preference handling to GeckoPreferences. r=liuche
Bug 917480 - Part 2: add 'Language' section to top-level preferences, allowing for browser locale switching. r=nalexander
* * *
Bug 917480 - Part 2d: compute locale list at build time.
Bug 917480 - Part 3: manifest changes for locale changes on API 17. r=nalexander

locale and layoutDirection need to appear together in android:configChanges
attributes. We specify these in any activity that we don't want Android to
automatically relaunch when a locale change occurs, which is most or all of
them.
Bug 917480 - Part 4: handle resetting to the system default locale. r=nalexander
Bug 917480 - Part 5: UI telemetry for locale switching. r=mfinkle
Bug 917480 - Part 6: tablet mode. r=nalexander