WebKitGTK+ 2.21.4 released!

This is a development release leading toward 2.22 series.

What’s new in the WebKitGTK+ 2.21.4 release?

• Switch to use a popup window with a tree view instead of a menu for option menu default implementation.
• Add API to run javascript from a WebKitWebView in an isolated world.
• Fix UI process crash in WebKitFaviconDatabase when pageURL is unset.
• Fix several crashes and rendering issues.

Thanks to all the contributors who made possible this release.