D23901: Remove the HTML/CSS validation plug-in

[David Faure]

dfaure added a reviewer: stefanocrocco.

REPOSITORY
  R226 Konqueror

REVISION DETAIL
  https://phabricator.kde.org/D23901

To: vkrause, dfaure, stefanocrocco
Cc: kde-doc-english, gennad, fbampaloukas, skadinna