Function is_same_origin

test/fixtures/wpt/resources/testharness.js:4978–4985

(w)

    }

    function is_same_origin(w) {
        try {
            'random_prop' in w;
            return true;
        } catch (e) {
            return false;
        }
    }

    /** Returns the 'src' URL of the first <script> tag in the page to include the file 'testharness.js'. */
    function get_script_url()