Back out de1c0246854c (bug 851057), 89a472c35979 (bug 873142), f849dec1a6df (bug 870496), 45fbd0b38bc5 (bug 873136) for incomprehensible Android reftest failures
bug 873902 - zero mark widths after GPOS positioning for Arabic fonts. r=jdaggett
bug 873902 - reftest for Arabic marks with Windows fonts. r=jdaggett