Add a windowtype attribute to the account wizard so that the 'Fake' add-on can close it.

im/content/accountWizard.xul

@@ -48,6 +48,7 @@
 ]>
 
 <wizard id="accountWizard" title="&windowTitle.label;"
+        windowtype="Messenger:accountWizard"
         onwizardfinish="return accountWizard.createAccount();"
         onload="accountWizard.onload();"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">