Poor antialiased edges on CSS3 transformed tiles

Original found on https://forum.qt.io/topic/56335/css-3d-transform-qtwebengine-qt-5-5-vs-cef3

In the demo https://www.webkit.org/blog-files/3d-transforms/poster-circle.html we have poor antialiasing on the edges of the tiles.

Due to how design each tile becomes a QSG node, so the issue may be in QSG.