Revert change that would decompose text if GPOS mark feature is available

https://github.com/harfbuzz/harfbuzz/issues/653#issuecomment-423905920

src/hb-ot-shape-normalize.cc

@@ -297,7 +297,9 @@ _hb_ot_shape_normalize (const hb_ot_shape_plan_t *plan,
   if (mode == HB_OT_SHAPE_NORMALIZATION_MODE_AUTO)
   {
     if (plan->has_mark)
-      mode = HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED;
+      // https://github.com/harfbuzz/harfbuzz/issues/653#issuecomment-423905920
+      //mode = HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED;
+      mode = HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS;
     else
       mode = HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS;
   }