window.set_icon_from_file(filePath) does not work on wayland, the icon is not set as the application icon. 

The same GJS application source runs fine when not using wayland.

Complete example:
https://github.com/optimisme/gjs-examples/blob/master/egIcon.js


The following source will return 'true' from 'set_icon_from_file' and won't report any error, but the icon won't be shown.


App.prototype.buildUI = function() {

    let result = false;

    this.window = new Gtk.ApplicationWindow({ application: this.application,
                                              title: this.title,
                                              default_height: 200,
                                              default_width: 200,
                                              window_position: Gtk.WindowPosition.CENTER });
    try {
        this.window.set_icon_from_file(path + '/assets/appIcon.png');
    } catch (err) {
        this.window.set_icon_name('application-x-executable');
    }

    this.label = new Gtk.Label({ label: "Hello icon" });
    this.window.add(this.label);
};