QtWebKit memory leaks (memory increases with every new page load)

Memory size of QtWebKit process increases with every new page load. Cleaning memory cache doesn't help.

Here is code example:
http://stackoverflow.com/questions/21357157/is-there-any-solution-for-the-qtwebkit-memory-leak

If I understood correctly, it was reported a long time ago:
http://qt-project.org/forums/viewthread/11105

But I couldn't find any solution or any explanation in documentation.