WebKitGTK+ 2.15.90 released!

This is a development release leading toward 2.16 series.

Add an API to add a custom tab into the print dialog.
Update cookie manager API to properly work with ephemeral sessions.
Fix rendering issues in long documents with transparent background.
Handle extended colors in cairo and texture mapper backends.
Release unused UpdateAtlas and reduce the tile coverage on memory pressure.
The media backend now stores preloaded media in /var/tmp instead of user cache dir.
Fix a deadlock when the media player is destroyed.
Fast replay on video hide/unhide on platforms with limited video buffer pools.
Fix network process crashes when loading custom URI schemes.
Fix video rendering when switching to accelerated compositing mode.
Fix several crashes and rendering issues.
Translation updates: Brazilian Portuguese.

Thanks to all the contributors who made possible this release.