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/misc/loginManager.js

@@ -2,7 +2,6 @@
 
 const GLib = imports.gi.GLib;
 const Gio = imports.gi.Gio;
-const Lang = imports.lang;
 const Mainloop = imports.mainloop;
 const Shell = imports.gi.Shell;
 const Signals = imports.signals;
@@ -70,10 +69,8 @@ function getLoginManager() {
     return _loginManager;
 }
 
-var LoginManagerSystemd = new Lang.Class({
-    Name: 'LoginManagerSystemd',
-
-    _init() {
+var LoginManagerSystemd = class {
+    constructor() {
         this._proxy = new SystemdLoginManager(Gio.DBus.system,
                                               'org.freedesktop.login1',
                                               '/org/freedesktop/login1');
@@ -82,7 +79,7 @@ var LoginManagerSystemd = new Lang.Class({
                                                '/org/freedesktop/login1/user/self');
         this._proxy.connectSignal('PrepareForSleep',
                                   this._prepareForSleep.bind(this));
-    },
+    }
 
     getCurrentSessionProxy(callback) {
         if (this._currentSession) {
@@ -129,7 +126,7 @@ var LoginManagerSystemd = new Lang.Class({
                 callback(this._currentSession);
             }
         });
-    },
+    }
 
     canSuspend(asyncCallback) {
         this._proxy.CanSuspendRemote((result, error) => {
@@ -141,7 +138,7 @@ var LoginManagerSystemd = new Lang.Class({
                 asyncCallback(canSuspend, needsAuth);
             }
         });
-    },
+    }
 
     listSessions(asyncCallback) {
         this._proxy.ListSessionsRemote((result, error) => {
@@ -150,11 +147,11 @@ var LoginManagerSystemd = new Lang.Class({
             else
                 asyncCallback(result[0]);
         });
-    },
+    }
 
     suspend() {
         this._proxy.SuspendRemote(true);
-    },
+    }
 
     inhibit(reason, callback) {
         let inVariant = GLib.Variant.new('(ssss)',
@@ -174,38 +171,36 @@ var LoginManagerSystemd = new Lang.Class({
                     callback(null);
                 }
             });
-    },
+    }
 
     _prepareForSleep(proxy, sender, [aboutToSuspend]) {
         this.emit('prepare-for-sleep', aboutToSuspend);
     }
-});
+};
 Signals.addSignalMethods(LoginManagerSystemd.prototype);
 
-var LoginManagerDummy = new Lang.Class({
-    Name: 'LoginManagerDummy',
-
+var LoginManagerDummy = class {
     getCurrentSessionProxy(callback) {
         // we could return a DummySession object that fakes whatever callers
         // expect (at the time of writing: connect() and connectSignal()
         // methods), but just never calling the callback should be safer
-    },
+    }
 
     canSuspend(asyncCallback) {
         asyncCallback(false, false);
-    },
+    }
 
     listSessions(asyncCallback) {
         asyncCallback([]);
-    },
+    }
 
     suspend() {
         this.emit('prepare-for-sleep', true);
         this.emit('prepare-for-sleep', false);
-    },
+    }
 
     inhibit(reason, callback) {
         callback(null);
     }
-});
+};
 Signals.addSignalMethods(LoginManagerDummy.prototype);