Trying to assign an icon from a file to a button like in

import QtQuick 2.2
import QtQuick.Controls 2.4

Button {
    icon.source: "/usr/share/icons/breath/emotes/22/face-smirk.svg"
}

results in no icon being shown. The current code interprets the filename as QString and tries to load an icon with that name from the theme, which obviously doesn't exist. This patch checks whether the icon points to a local file
and if it is loads it. If not it falls back to loading it from the theme.

Above code now correctly displays a face.
Ran systemsettings, checked QML KCMs' buttons for icons