* lisp/xwidget.el (xwidget-delete-zombies): Rewrite with dolist/memq
instead of mapcar/find.
* lisp/emacs-parallel/parallel.el lisp/emacs-parallel/parallel-remote.el:
Add Emacs Parallel.
* src/xwidget.c (Fset_frame_visible): Hack to force a frame to be
considered as visible to trigger the display engine.
* lisp/xwidget.el (xwidget-display): Force the display engine to create a
xwidget_view of the given xwidget.
* test/automated/test-xwidget.el: Add XWidget test suites.
* lisp/xwidget.el (xwidget-display): Return a useful value.
* test/automated/xwidget-tests.el (xwidget-view-p): Use `xwidget-display'.