Port message tray sources and notifications to class framework

Third step in the class framework port, now it's the turn of
MessageTray.Source and MessageTray.Notification, as well as
the various implementations around the shell.

https://bugzilla.gnome.org/show_bug.cgi?id=664436

js/ui/shellMountOperation.js

@@ -239,16 +239,13 @@ ShellMountQuestionDialog.prototype = {
 }
 Signals.addSignalMethods(ShellMountQuestionDialog.prototype);
 
-function ShellMountPasswordSource(message, icon, reaskPassword) {
-    this._init(message, icon, reaskPassword);
-}
-
-ShellMountPasswordSource.prototype = {
-    __proto__: MessageTray.Source.prototype,
+const ShellMountPasswordSource = new Lang.Class({
+    Name: 'ShellMountPasswordSource',
+    Extends: MessageTray.Source,
 
     _init: function(message, icon, reaskPassword) {
         let strings = message.split('\n');
-        MessageTray.Source.prototype._init.call(this, strings[0]);
+        this.parent(strings[0]);
 
         this._notification = new ShellMountPasswordNotification(this, strings, icon, reaskPassword);
 
@@ -256,21 +253,15 @@ ShellMountPasswordSource.prototype = {
         Main.messageTray.add(this);
         this.notify(this._notification);
     },
-}
+});
 Signals.addSignalMethods(ShellMountPasswordSource.prototype);
 
-function ShellMountPasswordNotification(source, strings, icon, reaskPassword) {
-    this._init(source, strings, icon, reaskPassword);
-}
-
-ShellMountPasswordNotification.prototype = {
-    __proto__: MessageTray.Notification.prototype,
+const ShellMountPasswordNotification = new Lang.Class({
+    Name: 'ShellMountPasswordNotification',
+    Extends: MessageTray.Notification,
 
     _init: function(source, strings, icon, reaskPassword) {
-        MessageTray.Notification.prototype._init.call(this, source,
-                                                      strings[0], null,
-                                                      { customContent: true,
-                                                        icon: icon });
+        this.parent(source, strings[0], null, { customContent: true, icon: icon });
 
         // set the notification to transient and urgent, so that it
         // expands out
@@ -305,7 +296,7 @@ ShellMountPasswordNotification.prototype = {
 
         this.source.emit('password-ready', text);
     }
-}
+});
 
 function ShellProcessesDialog(icon) {
     this._init(icon);