PHP Desktop is an open source project founded by Czarek Tomczak in
2012 to provide a way for developing native desktop GUI applications
using web technologies such as PHP, HTML5, JavaScript & SQLite. The
development workflow you are used to while creating web applications
remains the same. The step of turning an existing website into a
desktop application is basically a matter of copying it to the "www/"
directory.
PHP Desktop also releases Python Desktop and Ruby Desktop. It allows you to create a Windows app, that either uses the installed IE for the front-end, or uses an instance of Chrome (so definitely HTML5 support too) that is packaged with the app. It starts a local webserver, supports many databases with a PDO driver and you can layout the views in HTML and Javascript. You can download external resources like any other website/webapp, so it supports network related stuff too. The app ships with its own bare-bones version of Python, you can add libraries as desired.
I looked at all the answers before, as I had the exact same question as you, but PHP Desktop easily solved it for me.
https://code.google.com/p/phpdesktop/wiki/EmbeddingOtherScriptingLanguages