Same as bug #21884, but for libpangoft2, which pango_fc_font_description_from_pattern is being used.
Created attachment 24675 [details] patch
For the record, pango_fc_font_description_from_pattern is not used in the pango backend, but the freetype backend, which can be confusing;)
Comment on attachment 24675 [details] patch r=me
Landed in r37925.