Simplify the auto-updater implementations

We used to use Sparkle on OS X, and the design was reserved to be
extended to all platforms, which are all wrong now.

atom/browser/api/lib/auto-updater/auto-updater-mac.coffee

@@ -3,18 +3,4 @@
 
 autoUpdater.__proto__ = EventEmitter.prototype
 
-autoUpdater.quitAndInstall = ->
-  # If we don't have any window then quitAndInstall immediately.
-  BrowserWindow = require 'browser-window'
-  windows = BrowserWindow.getAllWindows()
-  if windows.length is 0
-    @_quitAndInstall()
-    return
-
-  # Do the restart after all windows have been closed.
-  app = require 'app'
-  app.removeAllListeners 'window-all-closed'
-  app.once 'window-all-closed', @_quitAndInstall.bind(this)
-  win.close() for win in windows
-
 module.exports = autoUpdater