Revert "Revert "Merge remote-tracking branch 'upstream/master' into bubble-tea""

This reverts commit a76dc9b333ef8b24e0ea20e50116abb1914ab285.
fix app_window_manager.js
Merge remote-tracking branch 'upstream/master' into bubble-tea-merge4

Conflicts:
	apps/system/js/app_window.js
	apps/system/js/simcard_dialog.js
	apps/system/test/unit/activities_test.js
	shared/test/unit/mocks/mock_navigator_moz_mobile_connections.js
Merge pull request #16939 from gasolin/bubble-tea-fix

Revert "Revert "Merge remote-tracking branch 'upstream/master' into bubb...
Merge remote-tracking branch 'upstream/master' into bubble-tea-merge4
Merge pull request #16975 from gasolin/bubble-tea-merge4

Bubble tea merge4
Bug 976986 - SettingsListener should have unobserve() method
Test travis again