use variable font feature to make bold font acceptable
@chpe
Submitted by Christian Persch Link to original bug (#794577)
Description
Now that we've removed faux-bold, we should try harder to find a suitable bold font.
Currently we try the bold font and if its width is over 10% more than the non-bold font's, we reject it and use the non-bold font instead.
Instead, if the font supports the opentype variable font feature, we could try to reduce the font stretch (making the font more condensed) and/or the weight (making it a bit less bold, but still some bold), until the font becomes acceptable.
The same applies to the italic font, too.
Version: git master