Bug 837251 - Compose textarea doesn't occupy available screen space or show bounding box. r=asuth

Includes some minor review fixes by asuth.
Bug 960901 - (lockscreen-instance) [LockScreen] Make LockScreen as an instantiable function
Merge pull request #16345 from asutherland/email-contenteditable

Bug 837251 - Compose textarea doesn't occupy available screen space or show bounding box. r=asuth
Merge pull request #16313 from snowmantw/issue960901-instantiable-lockscreen

Bug 960901 - (lockscreen-instance) [LockScreen] Make LockScreen as an instantiable function
Bug 972160 - Run specific marionette tests for 30 times on Travis.
Merge pull request #16244 from evanxd/bug-972160

Bug 972160 - Run specific marionette tests for multiple times on Travis.
Bug 968692 - [settings] add marionette test for Screen lock panel

- add lockscreen related test