kde-apps/plasma-runtime depends on dev-qt/qtwebkit:4 which is ancient and will never see any security updates.
plasma-runtime itself is of no use for in-tree Plasma versions and is currently blocked from removal for a single rdepend.
Author: Michał Górny <email@example.com>
AuthorDate: Wed Jul 5 11:52:40 2017
Commit: Michał Górny <firstname.lastname@example.org>
CommitDate: Wed Jul 5 12:00:09 2017
kde-apps/plasma-runtime: Remove last-rited pkg, #620792