[polari] MainWindow: fix function call syntax

[Giovanni Campagna <gcampagna src gnome org>]

commit 703c4e800f89996e14968e78d6d5f6ed37560e63
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Sat Feb 1 21:02:24 2014 +0100

    MainWindow: fix function call syntax
    
    These are not constructors.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=723432

 src/mainWindow.js |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/mainWindow.js b/src/mainWindow.js
index cd51687..1384fcb 100644
--- a/src/mainWindow.js
+++ b/src/mainWindow.js
@@ -35,13 +35,13 @@ const MainWindow = new Lang.Class({
         overlay.add_overlay(app.notificationQueue.widget);
         overlay.add_overlay(app.commandOutputQueue.widget);
 
-        this._accountsMonitor = new AccountsMonitor.getDefault();
+        this._accountsMonitor = AccountsMonitor.getDefault();
         this._accountsMonitor.connect('account-status-changed',
                                       Lang.bind(this, this._onAccountChanged));
         this._accountsMonitor.connect('account-added',
                                       Lang.bind(this, this._onAccountChanged));
 
-        this._roomManager = new ChatroomManager.getDefault();
+        this._roomManager = ChatroomManager.getDefault();
         this._roomManager.connect('room-added',
                                   Lang.bind(this, this._roomAdded));
         this._roomManager.connect('room-removed',