Fix nonstandard initialisation code for fill/parameter/slot widgets

core/modules/widgets/fill.js

@@ -22,7 +22,7 @@ var FillWidget = function(parseTreeNode,options) {
 /*
 Inherit from the base widget class
 */
-FillWidget.prototype = Object.create(Widget.prototype);
+FillWidget.prototype = new Widget();
 
 exports.fill = FillWidget;
 

core/modules/widgets/parameters.js

@@ -23,7 +23,7 @@ var ParametersWidget = function(parseTreeNode,options) {
 /*
 Inherit from the base widget class
 */
-ParametersWidget.prototype = Object.create(Widget.prototype);
+ParametersWidget.prototype = new Widget();
 
 /*
 Render this widget into the DOM

core/modules/widgets/slot.js

@@ -23,7 +23,7 @@ var SlotWidget = function(parseTreeNode,options) {
 /*
 Inherit from the base widget class
 */
-SlotWidget.prototype = Object.create(Widget.prototype);
+SlotWidget.prototype = new Widget();
 
 /*
 Render this widget into the DOM