gistfile1.txt

const Gtk = imports.gi.Gtk;
const WebKit2 = imports.gi.WebKit2;
const Lang = imports.lang;
Gtk.init(null);

// WebKit2.WebContext.get_default().register_uri_scheme('foo', function () {})

const MyWebView = new Lang.Class({
    Name: 'MyWebView',
    GTypeName: 'MyWebView',
    Extends: WebKit2.WebView,

    _init: function (props) {
        props = props || {};
        this.parent(props);

        this.web_context.register_uri_scheme('ekn', function () {});
    },
});

let webview = new MyWebView();