Qt/Mac : text rendering issues with QRawFont made from data or font file

I recently discovered a text rendering issue in the CoreText fontengine that is triggered by QtWebKit 5.212: see https://github.com/annulen/webkit/issues/703 .

Trying to reproduce this issue in a simple demonstrator I found what might be an even worse bug.

Rendering a string in a QTextLayout using GlyphRuns and a QRawFont created from a font file or a QByteArray gives a pile of glyphs instead of a string, as if the pen is not advanced. This happens with the standard CoreText fontengine (https://user-images.githubusercontent.com/1756884/34446639-0e98558c-ecdd-11e7-98d0-c2c4ce33db74.png) but not with the FreeType fontengine (`-platform cocoa:fontengine=freetype`: https://user-images.githubusercontent.com/1756884/34446646-19a8ad5a-ecdd-11e7-9352-08a61a89e00a.png). Rendering is fine when using a QRawFont created from a QFont.

The demonstrator code can be found here: github.com/RJVB/fontweightissue-qt5.git .