[gnome-shell] (4 commits) Non-fast-forward update to branch wip/chergert/3-28-perf-fixes

[Christian Hergert <chergert src gnome org>]

The branch 'wip/chergert/3-28-perf-fixes' 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:

  e5460b5... ShellAppCache: add cache to help keep I/O off main thread
  4d678c8... shell-global: Make saving of persistent state asynchronous
  88f4668... global: force fsync() to worker thread when saving state
  b5b65c3... ShellAppSystem: use ShellAppCache to access GAppInfo
  2e1b6aa... util: cache local GTimeZone
  f131531... appDisplay: use ShellAppCache to translate folder names
  b60d919... appDisplay: use ShellAppCache to access GAppInfo

Commits added to the branch:

  07b11f9... shell-global: Make saving of persistent state asynchronous
  287a34a... global: force fsync() to worker thread when saving state
  e63fab0... environment: reduce calls to g_time_zone_new_local()
  1f6c6a5... app-cache: add ShellAppCache for GAppInfo caching