Bug 863310 - Show the stack traces for failing tests, r=lightsofapollo, a=test-only
Bug 864314 - Lazyl10n tests from the Dialer should be re-enabled  r=arcturus
Bug 860681 - Icons revert to default in 3rd party apps r=vivien

* hopefully finally fix reliably the "ensure panning" test by mocking
  `requestAnimationFrame`
* call `markDirtyState` in all situations ensure that our state is saved in
  IndexedDB
* add tests to ensure the state is saved in these situations. Had to move the
  initialization of some objects to `doInit` so that we can correctly reset the
  object state.
* don't try to load a default icon if we already have an icon
Merge pull request #9300 from jonallengriffin/unitstacks

Bug 863310 - Show the stack traces for failing tests, r=lightsofapollo, ...
Merge pull request #9337 from albertopq/fixing-dialer-tests

Bug 864314 - Lazyl10n tests from the Dialer should be re-enabled  r=arcturus
Bug 864476 - [FTE] the progression bar should be hidden in some panels r=arcturus

Moved the className calculation before the switch-case so that we can override
it inside the switch-case.

Added a test case to prevent future regressions
Bug 863443 - Contribution Guidelines not Discoverable r=julien

Add a `CONTRIBUTING.md` file to the root of the project. GitHub.com will
display this file to users attempting to open issues and pull requests
through its web interface[1].

r=julienw

[1] https://github.com/blog/1184-contributing-guidelines
Bug 864864 - fix again update manager unreliable tests r=etienne
Bug 862752 - Extend pretty date helper
Bug 811083 - Add preset option for client-side username validation
Merge pull request #9247 from KevinGrandon/bug_862752_alarm_translations

Bug 862752 - Extend pretty date helper
Merge pull request #9319 from gaye/bug-811083

Bug 811083 - Add preset option for client-side username validation
Bug 796588 - Don't allow user to setup same account twice r=lightsofapollo
Merge pull request #9341 from lightsofapollo/leob2g-Bug_796588_Can_Add_multiple_same_account

Bug 796588 - Don't allow user to setup same account twice r=lightsofapol...
Bug 858463 - Hide the subtitle 'Accounts' if there is no account in settings
Merge pull request #9219 from gaye/bug-858463

Bug 858463 - Hide the subtitle 'Accounts' in settings if no accounts
Fix advanced settings view test
Merge pull request #9363 from gaye/fix-broken-view-test

Fix advanced settings view test
Add missing semicolon to end of line in advanced settings view
Merge pull request #9364 from gaye/fix-lint-error

Add missing semicolon to end of line in advanced settings view