bug 985220 - remove the old GDI, Uniscribe and DWrite text-shaping code paths, as we now use HarfBuzz or Graphite for all shaping on Windows. r=jdaggett
bug 985220 pt 2 - replace the use of GetGlyphIndicesW with ScriptGetCMap in gfxGDIFont::GetGlyph. r=jdaggett
bug 985220 pt 3 - when zeroing the width of mark glyphs, also update their offset to overstrike preceding glyph. r=behdad