cleanup: Port non-GObject classes to JS6 classes

ES6 finally adds standard class syntax to the language, so we can
replace our custom Lang.Class framework with the new syntax. Any
classes that inherit from GObject will need special treatment,
so limit the port to regular javascript classes for now.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/361

js/ui/status/rfkill.js

@@ -1,7 +1,6 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
 
 const Gio = imports.gi.Gio;
-const Lang = imports.lang;
 const Signals = imports.signals;
 
 const Main = imports.ui.main;
@@ -16,10 +15,8 @@ const OBJECT_PATH = '/org/gnome/SettingsDaemon/Rfkill';
 const RfkillManagerInterface = loadInterfaceXML('org.gnome.SettingsDaemon.Rfkill');
 const RfkillManagerProxy = Gio.DBusProxy.makeProxyWrapper(RfkillManagerInterface);
 
-var RfkillManager = new Lang.Class({
-    Name: 'RfkillManager',
-
-    _init() {
+var RfkillManager = class {
+    constructor() {
         this._proxy = new RfkillManagerProxy(Gio.DBus.session, BUS_NAME, OBJECT_PATH,
                                              (proxy, error) => {
                                                  if (error) {
@@ -30,28 +27,28 @@ var RfkillManager = new Lang.Class({
                                                                      this._changed.bind(this));
                                                  this._changed();
                                              });
-    },
+    }
 
     get airplaneMode() {
         return this._proxy.AirplaneMode;
-    },
+    }
 
     set airplaneMode(v) {
         this._proxy.AirplaneMode = v;
-    },
+    }
 
     get hwAirplaneMode() {
         return this._proxy.HardwareAirplaneMode;
-    },
+    }
 
     get shouldShowAirplaneMode() {
         return this._proxy.ShouldShowAirplaneMode;
-    },
+    }
 
     _changed() {
         this.emit('airplane-mode-changed');
     }
-});
+};
 Signals.addSignalMethods(RfkillManager.prototype);
 
 var _manager;
@@ -63,12 +60,9 @@ function getRfkillManager() {
     return _manager;
 }
 
-var Indicator = new Lang.Class({
-    Name: 'RfkillIndicator',
-    Extends: PanelMenu.SystemIndicator,
-
-    _init() {
-        this.parent();
+var Indicator = class extends PanelMenu.SystemIndicator {
+    constructor() {
+        super();
 
         this._manager = getRfkillManager();
         this._manager.connect('airplane-mode-changed', this._sync.bind(this));
@@ -90,12 +84,12 @@ var Indicator = new Lang.Class({
 
         Main.sessionMode.connect('updated', this._sessionUpdated.bind(this));
         this._sessionUpdated();
-    },
+    }
 
     _sessionUpdated() {
         let sensitive = !Main.sessionMode.isLocked && !Main.sessionMode.isGreeter;
         this.menu.setSensitive(sensitive);
-    },
+    }
 
     _sync() {
         let airplaneMode = this._manager.airplaneMode;
@@ -110,5 +104,5 @@ var Indicator = new Lang.Class({
             this._offItem.label.text = _("Use hardware switch to turn off");
         else
             this._offItem.label.text = _("Turn Off");
-    },
-});
+    }
+};