1. @DomName('FontFaceSetForEachCallback')
  2. @Experimental()
void FontFaceSetForEachCallback(FontFace fontFace, FontFace fontFaceAgain, FontFaceSet set)

Source 

@DomName('FontFaceSetForEachCallback')
@Experimental() // untriaged
typedef void FontFaceSetForEachCallback(
    FontFace fontFace, FontFace fontFaceAgain, FontFaceSet set);