Fix source selector generator not ending with stylesheets using bad mimetype
Fix source selector generator not ending with stylesheets using bad mimetype

prepare/TestWeasyPrint,marclaporte/WeasyPrint,andrewleech/WeasyPrint,prepare/TestWeasyPrint,marclaporte/WeasyPrint,Kozea/WeasyPrint,jasco/WeasyPrint,jasco/WeasyPrint,andrewleech/WeasyPrint,Kozea/WeasyPrint