keyboard: Ensure to resize keys after layer change

The keys possibly need resizing after a (new) layer has been set, there's
however calling places that don't. Instead, fold this._redraw() into
setActiveLayer().

js/ui/keyboard.js

@@ -684,12 +684,10 @@ var Keyboard = new Lang.Class({
 
     _onLevelChanged: function (level) {
         this._setActiveLayer(level);
-        this._redraw();
     },
 
     _onGroupChanged: function () {
         this._setActiveLayer(0);
-        this._redraw();
     },
 
     _onKeyboardGroupsChanged: function(keyboard) {
@@ -706,6 +704,7 @@ var Keyboard = new Lang.Class({
         }
 
         this._current_page = layers[activeLevel];
+        this._redraw();
         this._current_page.show();
     },