StatusBar: Respond properly to global expand message

Fix timing issue in PhoneStatusBar#animateExpand(). Also, notification panel
drag handle (when expanded) reflects movement immediately.

To test animateExpand():
  $ adb shell service call statusbar 1

Bug: 6629916
Change-Id: I22bb09fc4c9d97c93ba8d7aed8921b60f5ebd610