D4996: Fix invalid reference of toolTipArea.

[Xuetian Weng]

xuetianweng added a reviewer: Plasma.

REPOSITORY
  R119 Plasma Desktop

REVISION DETAIL
  https://phabricator.kde.org/D4996

To: xuetianweng, hein, #plasma
Cc: plasma-devel, progwolff, lesliezhai, ali-mohamed, jensreuterberg, abetts, 
sebas, apol