FrameSvg: make hasElementPrefix() also handle prefix with trailing -

Authored by kossebau on May 12 2019, 11:36 PM.

Description

FrameSvg: make hasElementPrefix() also handle prefix with trailing -

Summary:
there are a few places which potentially pass a prefix with a trailing -,
e.g. if using directly the value of FrameSvg::prefix() or
FrameSvg::actualPrefix(). Support the assumption in such code, unbreaking
its currently not working behaviour.

Reviewers: Plasma, mart

Reviewed By: Plasma, mart

Subscribers: apol, kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D21174