Use beforeunload instead of unload

unload is asynchronous in Chrome 36 and so saving the state while
reloading may not happen before the state is read on the new render
process.

src/atom.coffee

@@ -311,10 +311,10 @@ class Atom extends Model
     @requireUserInitScript()
     @menu.update()
 
-    $(window).on 'unload', =>
+    $(window).on 'beforeunload', =>
       $(document.body).css('visibility', 'hidden')
       @unloadEditorWindow()
-      false
+      null
 
     @displayWindow()
 

src/window-event-handler.coffee

@@ -37,11 +37,13 @@ class WindowEventHandler
       @reloadRequested = false
       confirmed
 
-    @subscribe $(window), 'blur unload', ->
+    @subscribe $(window), 'blur beforeunload', ->
       atom.storeDefaultWindowDimensions()
+      null
 
-    @subscribe $(window), 'unload', ->
+    @subscribe $(window), 'beforeunload', ->
       atom.storeWindowDimensions()
+      null
 
     @subscribeToCommand $(window), 'window:toggle-full-screen', -> atom.toggleFullScreen()