Use WebContents.prototype.isLoading instead of defunct .loaded

Fixes cmd-o interaction.

src/browser/atom-window.coffee

@@ -88,7 +88,7 @@ class AtomWindow
       hash: encodeURIComponent(JSON.stringify(loadSettings))
 
   getLoadSettings: ->
-    if @browserWindow.webContents?.loaded
+    if @browserWindow.webContents? and not @browserWindow.webContents.isLoading()
       hash = url.parse(@browserWindow.webContents.getUrl()).hash.substr(1)
       JSON.parse(decodeURIComponent(hash))