layoutManager: Subclass GObject.Object

LayoutManager is currently a pure JavaScript class that
relies on the rudimentary Signals.addSignalMethods() to
handle signals. This is an inefficient implementation of
one of the most central classes in GNOME Shell.

In addition to removing Shell.GenericContainer, then,
turn LayoutManager into a proper GObject.Object subclass.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/153

js/ui/layout.js

@@ -177,8 +177,16 @@ const defaultParams = {
 
 var LayoutManager = new Lang.Class({
     Name: 'LayoutManager',
+    Extends: GObject.Object,
+    Signals: { 'hot-corners-changed': {},
+               'startup-complete': {},
+               'startup-prepared': {},
+               'monitors-changed': {},
+               'keyboard-visible-changed': { param_types: [GObject.TYPE_BOOLEAN] } },
 
     _init() {
+        this.parent();
+
         this._rtl = (Clutter.get_default_text_direction() == Clutter.TextDirection.RTL);
         this.monitors = [];
         this.primaryMonitor = null;
@@ -1069,7 +1077,6 @@ var LayoutManager = new Lang.Class({
         this._queueUpdateRegions();
     },
 });
-Signals.addSignalMethods(LayoutManager.prototype);
 
 
 // HotCorner: