WebKitGTK+ 2.11.90 released!

This is a development release leading toward 2.12 series.

Switch to use overlay scrollbars like all other GTK+ widgets and ensure the behavior is consistent with GTK+ too.
Limit the number of tiles according to the visible area. This was causing a huge memory consumption with some websites.
Fix toggle buttons rendering with GTK+ 3.19.
Fix HTTP authentication dialog rendering when accelerated compositing mode is enabled.
Use G_TYPE_ERROR instead of G_TYPE_POINTER for GError parameters of signals.
Fix several memory leaks.

Thanks to all the contributors who made possible this release.