[gnome-shell] (5 commits) Non-fast-forward update to branch wip/rstrode/login-screen-extensions

[Marge Bot <marge-bot src gnome org>]

The branch 'wip/rstrode/login-screen-extensions' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  d9fdae4... extensionSystem: Get rid of _enabled boolean optimization
  67beed2... extensionSystem: Allow extensions to run on the login scree
  1198653... sessionMode: Allow extensions at the login and unlock scree
  d28f3cf... sessionMode: Drop allowExtensions property

Commits added to the branch:

  2dcbf5f... theme: Fix high-contrast switches (*)
  d64629e... extensionSystem: Get rid of _enabled boolean optimization
  64b9718... extensionSystem: Allow extensions to run on the login scree
  9526e86... sessionMode: Allow extensions at the login and unlock scree
  2b409dc... sessionMode: Drop allowExtensions property

(*) This commit already existed in another branch; no separate mail sent