Make sure that editor is visible when adding description. Fixes #2163

[UX] Make sure that HTML editor is visible when adding meta tag
description text from *Add description* menu action.
Avoids situation that "Add description" seems to have no visible
results for novice users.
Merge pull request #2164 from peterblazejewicz/fix/force-html-editor-state

Make sure HTML editor is visible when adding description. Fixes #2163