Incorrect page margins when printing

Found on stackoverflow: https://stackoverflow.com/questions/47900417/qt-webengine-incorrect-page-margins-when-printing

1.) WebEngine picks up the page layout from the provided QPrinter
2.) PDFium renders the page to a temporary PDF with these margins
3.) then passes it back to the API layer
4.) and there QPrinter applies its margins one more time when printing the page.