https://wiki.qt.io/New_Features_in_Qt_5.6#Removed_Modules
With Qt 5.6 the following modules are no longer part of the release packages, but users can still build them from source:
- Qt WebKit
- Qt Declarative (Qt Quick 1)
http://doc.qt.io/qt-5/qtwebenginewidgets-qtwebkitportingguide.html