Bug#862452: Update to newer QtWebKit

[Konstantin Tokarev <annulen@yandex.ru>]

Note that there is unofficial package already:

http://repo.paretje.be/unstable/#

See packages libqt5webkit5, libqt5webkit5-dev

Git repo of package is at https://gitlab.com/paretje/qtwebkit/tree/master/debian

Package is loosely based of webkitgtk's, and contains a few build dependencies that are not actually needed:

libharfbuzz-dev, libfreetype6-dev, libfontconfig1-dev (these are used when qtbase is built, not directly in qtwebkit)
libgnutls28-dev, libsoup2.4-dev, libenchant-dev, geoclue-2.0, libsecret-1-dev - not used at all
libxt-dev - probably unused as well

Otherwise, packaging files look good to me
-- 
Regards,
Konstantin