pangocairo hexboxes don't take actual font size into account
Submitted by Behdad Esfahbod
Link to original bug (#695163)
Description
Instead of getting fontsize from the font desc, we should get it from the font matrix of the scaled font.
An example of where current code doesn't work is with recent cairo/fontconfig and hexbox being rendered using a scaled bitmap font. The scale factor in such situations comes from FC_MATRIX and is NOT reflected in the font_desc size of the loaded font. As a result, currently we get hexbox that is not the same size of the actual bitmap font.