function fetch_tests_from_window(window) {
        return tests.fetch_tests_from_window(window);
    }
Aggregate tests from separate windows or iframes
into the current document as if they were all part of the same test file.

The document of the second window (or iframe) should include
``testharness.js``, but not ``testharnessreport.js``, and use
:js:func:`test`, :js:func:`async_test`, and :js:func:`promise_test` in
the usual manner.

@param {Window} window - The window to fetch tests from.