See https://github.com/annulen/webkit/wiki

QtWebKit in the official Qt tarballs is based on an unmaintained copy of
WebKit. This updated version is about 3 years newer and contains even more
security fixes from WebKit���s trunk (hence ���major��� severity). It���s mostly a
drop-in replacement with ABI compatibility.

It was merged into http://code.qt.io/cgit/qt/qtwebkit.git/ (see dev and 5.212
branches). It was decided to use a separate release schedule from Qt, therefore
the version numbers differ (212 refers to it being based on WebKitGTK 2.12.x).
Old QtWebKit will not be released anymore.

Other distros are taking this step as well:
(Fedora)
http://lupinix.blogspot.de/2017/06/improving-qtwebkit-security-for-fedora.html
(Gentoo) https://bugs.gentoo.org/show_bug.cgi?id=624404
(Arch Linux)
https://lists.archlinux.org/pipermail/arch-dev-public/2017-June/028895.html
(Debian) https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=862452
(Void Linux) https://github.com/voidlinux/void-packages/pull/6876

Notes for OBS:
No change to the RAM requirements (8 GiB is just barely enough for 4 build
jobs), but it���ll require more disk space. I���d say 15-20 GB in _constraints.
Build system switches from qmake to CMake + Ninja.

QtDeclarative packaging currently has a minor bug that causes the build to fail
because Qt5Quick_PRIVATE_INCLUDE_DIRS is unset in the CMake module (see
boo#1053573).