[FIX] web: correctly use function actions

actions can be defined by a function, but the action manager was changed
to try to instantiate it instead of simply executing it.

addons/web/static/src/js/views.js

@@ -446,7 +446,7 @@ instance.web.ActionManager = instance.web.Widget.extend({
 
         if (!(ClientWidget.prototype instanceof instance.web.Widget)) {
             var next;
-            if ((next = new ClientWidget(this, action))) {
+            if ((next = ClientWidget(this, action))) {
                 return this.do_action(next, options);
             }
             return $.when();