The module WebKitWidgets depends on:
- Qt5MultimediaWidgets.dll
- Qt5OpenGL.dll
- Qt5PrintSupport.dll
- Qt5WebKit.dll
- Qt5Multimedia.dll
- Qt5Widgets.dll
- Qt5Network.dll
- Qt5Sensors.dll
- Qt5Gui.dll
- Qt5Core.dll
- MSVCP100.dll and MSVCR100.dll
- (KERNEL32.dll)
That's why you need those DLLs. If you don't want to ship all these, consider removing the webkitwidgets module.
You can inspect your application dependencies using tools like dependency walker or CFF explorer. These tools prove helpful when you have these kind of problems, you can easily explore dependencies and dependencies of the dependencies in your case ;)