[gnome-shell] (5 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:

  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()
  0dd77f8... app-cache: add ShellAppCache for GAppInfo caching

Commits added to the branch:

  4cac5b4... shell/app-system: Monitor for icon theme changes
  24f400d... shell-global: Make saving of persistent state asynchronous
  f3082a3... global: force fsync() to worker thread when saving state
  92cfb9a... environment: reduce calls to g_time_zone_new_local()
  7f7965d... app-cache: add ShellAppCache for GAppInfo caching