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/windowMenu.js

@@ -1,7 +1,6 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*
 
 const Gtk = imports.gi.Gtk;
-const Lang = imports.lang;
 const Meta = imports.gi.Meta;
 const St = imports.gi.St;
 const Shell = imports.gi.Shell;
@@ -11,12 +10,9 @@ const Main = imports.ui.main;
 const PopupMenu = imports.ui.popupMenu;
 const RemoteMenu = imports.ui.remoteMenu;
 
-var WindowMenu = new Lang.Class({
-    Name: 'WindowMenu',
-    Extends: PopupMenu.PopupMenu,
-
-    _init(window, sourceActor) {
-        this.parent(sourceActor, 0, St.Side.TOP);
+var WindowMenu = class extends PopupMenu.PopupMenu {
+    constructor(window, sourceActor) {
+        super(sourceActor, 0, St.Side.TOP);
 
         this.actor.add_style_class_name('window-menu');
 
@@ -24,7 +20,7 @@ var WindowMenu = new Lang.Class({
         this.actor.hide();
 
         this._buildMenu(window);
-    },
+    }
 
     _buildMenu(window) {
         let type = window.get_window_type();
@@ -177,16 +173,13 @@ var WindowMenu = new Lang.Class({
         if (!window.can_close())
             item.setSensitive(false);
     }
-});
+};
 
-var AppMenu = new Lang.Class({
-    Name: 'AppMenu',
-    Extends: RemoteMenu.RemoteMenu,
-
-    _init(window, sourceActor) {
+var AppMenu = class extends RemoteMenu.RemoteMenu {
+    constructor(window, sourceActor) {
         let app = Shell.WindowTracker.get_default().get_window_app(window);
 
-        this.parent(sourceActor, app.menu, app.action_group);
+        super(sourceActor, app.menu, app.action_group);
 
         this.actor.add_style_class_name('fallback-app-menu');
         let variant = window.get_gtk_theme_variant();
@@ -196,12 +189,10 @@ var AppMenu = new Lang.Class({
         Main.layoutManager.uiGroup.add_actor(this.actor);
         this.actor.hide();
     }
-});
+};
 
-var WindowMenuManager = new Lang.Class({
-    Name: 'WindowMenuManager',
-
-    _init() {
+var WindowMenuManager = class {
+    constructor() {
         this._manager = new PopupMenu.PopupMenuManager({ actor: Main.layoutManager.dummyCursor });
 
         this._sourceActor = new St.Widget({ reactive: true, visible: false });
@@ -209,7 +200,7 @@ var WindowMenuManager = new Lang.Class({
             this._manager.activeMenu.toggle();
         });
         Main.uiGroup.add_actor(this._sourceActor);
-    },
+    }
 
     showWindowMenuForWindow(window, type, rect) {
         let menuType = (type == Meta.WindowMenuType.WM) ? WindowMenu : AppMenu;
@@ -239,4 +230,4 @@ var WindowMenuManager = new Lang.Class({
             window.disconnect(destroyId);
         });
     }
-});
+};