cleanup: Port GObject classes to JS6 classes

GJS added API for defining GObject classes with ES6 class syntax
last cycle, use it to port the remaining Lang.Class classes to
the new syntax.

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

js/ui/closeDialog.js

@@ -4,7 +4,6 @@ const Clutter = imports.gi.Clutter;
 const Gio = imports.gi.Gio;
 const GLib = imports.gi.GLib;
 const GObject = imports.gi.GObject;
-const Lang = imports.lang;
 const Meta = imports.gi.Meta;
 const Shell = imports.gi.Shell;
 
@@ -16,31 +15,29 @@ var FROZEN_WINDOW_BRIGHTNESS = -0.3
 var DIALOG_TRANSITION_TIME = 0.15
 var ALIVE_TIMEOUT = 5000;
 
-var CloseDialog = new Lang.Class({
-    Name: 'CloseDialog',
-    Extends: GObject.Object,
+var CloseDialog = GObject.registerClass({
     Implements: [ Meta.CloseDialog ],
     Properties: {
         'window': GObject.ParamSpec.override('window', Meta.CloseDialog)
     },
-
+}, class CloseDialog extends GObject.Object {
     _init(window) {
-        this.parent();
+        super._init();
         this._window = window;
         this._dialog = null;
         this._tracked = undefined;
         this._timeoutId = 0;
         this._windowFocusChangedId = 0;
         this._keyFocusChangedId = 0;
-    },
+    }
 
     get window() {
         return this._window;
-    },
+    }
 
     set window(window) {
         this._window = window;
-    },
+    }
 
     _createDialogContent() {
         let tracker = Shell.WindowTracker.get_default();
@@ -52,7 +49,7 @@ var CloseDialog = new Lang.Class({
                          "continue or force the application to quit entirely.");
         let icon = new Gio.ThemedIcon({ name: 'dialog-warning-symbolic' });
         return new Dialog.MessageDialogContent({ icon, title, subtitle });
-    },
+    }
 
     _initDialog() {
         if (this._dialog)
@@ -72,7 +69,7 @@ var CloseDialog = new Lang.Class({
                                  key:    Clutter.Escape });
 
         global.focus_manager.add_group(this._dialog);
-    },
+    }
 
     _addWindowEffect() {
         // We set the effect on the surface actor, so the dialog itself
@@ -83,21 +80,21 @@ var CloseDialog = new Lang.Class({
         let effect = new Clutter.BrightnessContrastEffect();
         effect.set_brightness(FROZEN_WINDOW_BRIGHTNESS);
         surfaceActor.add_effect_with_name("gnome-shell-frozen-window", effect);
-    },
+    }
 
     _removeWindowEffect() {
         let windowActor = this._window.get_compositor_private();
         let surfaceActor = windowActor.get_first_child();
         surfaceActor.remove_effect_by_name("gnome-shell-frozen-window");
-    },
+    }
 
     _onWait() {
         this.response(Meta.CloseDialogResponse.WAIT);
-    },
+    }
 
     _onClose() {
         this.response(Meta.CloseDialogResponse.FORCE_CLOSE);
-    },
+    }
 
     _onFocusChanged() {
         if (Meta.is_wayland_compositor())
@@ -128,7 +125,7 @@ var CloseDialog = new Lang.Class({
         });
 
         this._tracked = shouldTrack;
-    },
+    }
 
     vfunc_show() {
         if (this._dialog != null)
@@ -162,7 +159,7 @@ var CloseDialog = new Lang.Class({
                            time: DIALOG_TRANSITION_TIME,
                            onComplete: this._onFocusChanged.bind(this)
                          });
-    },
+    }
 
     vfunc_hide() {
         if (this._dialog == null)
@@ -191,7 +188,7 @@ var CloseDialog = new Lang.Class({
                                dialog.destroy();
                            }
                          });
-    },
+    }
 
     vfunc_focus() {
         if (this._dialog)