WebKitGTK 2.29.3 released!

This is a development release leading toward 2.30 series.

Add webkit_authentication_request_get_security_origin.
Change the cookies accept policy to always when no-third-party is set and ITP is enabled.
Fix web process hangs on large GitHub pages.
Bubblewrap sandbox should not attempt to bind empty paths.
Add support for sndio to bubblewrap sandbox.
Also handle dark themes when the name ends with -Dark.
Fix a race condition causing a crash in media player.
Fix several crashes and rendering issues.

Thanks to all the contributors who made possible this release.