Revert "Fix build with WebKit master"

This reverts commit 23c3de000eddd33b8dfe2988dda10d01099505a7.

I don't think this is right, webkit_dom_element_get_class_list() is
defined in WebKitDOMElementUnstable.h now in WebKit master
Make it build with current WebKit master

WebKitWebViewGroup has been removed .
web-extensions: Release EphyWebExtensionProxy when the web extension is destroyed

We were leaking all EphyWebExtensionProxy objects because they were
released when the bus named was unwatched, and we were unwatching the
name in the object dispose method. So, now unref the object when the
name is vanished instead. Also added a GCancellable to use in all async
operations.
Bump WebKitGTK+ requirements to 2.5.1

And remove all ifdefs.
Update about dialog copyright year
data: Set <name> and <summary> fields in the AppData file

We want to use different values in the software center search results.
Updated Basque language
Fix floating bar style with GTK+ master

This has been transparent for a month or two now. I think the fix is
by Lapo Calamandrei.

https://bugzilla.gnome.org/show_bug.cgi?id=734306
Add support for downloads from evince browser plugin

Enable javascript popups in WebKit by default and block them from
epiphany in the policy checker callback. Evince browser plugin allows to
download the current document only when the user agent contains
Epiphany, by using a special target frame name. When we detect that
target name in the policy checker callback we convert the request into a
download.
ephy-certificate-dialog: add missing periods
Set add language window transient for the preferences dialog
Reduce warning spew from deprecated properties

Mostly this is xalign->halign and margin_start instead of GtkAlignment.
There are still a bunch of warnings, but I think they're coming from WebKit.

The patch is mostly unreadable due to the GtkAlignment removal, but
there should not be any functional changes.
Fix links opened in a new window
Updated Spanish translation